From dfece0870967cbbc250e23645f21454670ff6d50 Mon Sep 17 00:00:00 2001
From: Olivier Laviale <olivier.laviale@gmail.com>
Date: Sun, 13 Mar 2016 23:12:13 +0100
Subject: [PATCH] Drop PHP 5.6 support

---
 .travis.yml                                   |   5 +-
 README.md                                     |   2 +-
 composer.json                                 |   2 +-
 lib/ActiveRecord.php                          |  10 +-
 lib/ActiveRecord/ActiveRecordCache.php        |   4 +-
 .../ActiveRecordClassNotValid.php             |  12 +-
 lib/ActiveRecord/BelongsToRelation.php        |   6 +-
 lib/ActiveRecord/Connection.php               |  51 ++++---
 .../ConnectionAlreadyEstablished.php          |   6 +-
 lib/ActiveRecord/ConnectionCollection.php     |  12 +-
 lib/ActiveRecord/ConnectionNotDefined.php     |   9 +-
 lib/ActiveRecord/ConnectionNotEstablished.php |   7 +-
 lib/ActiveRecord/ConnectionOptions.php        |   2 +-
 lib/ActiveRecord/CreatedAtProperty.php        |   2 +-
 lib/ActiveRecord/DateProperty.php             |   2 +-
 lib/ActiveRecord/DateTimeProperty.php         |   2 +-
 lib/ActiveRecord/DateTimePropertySupport.php  |   2 +-
 lib/ActiveRecord/Driver.php                   |  12 +-
 lib/ActiveRecord/Driver/BasicDriver.php       |   8 +-
 lib/ActiveRecord/Driver/MySQLDriver.php       |  14 +-
 lib/ActiveRecord/Driver/SQLiteDriver.php      |   8 +-
 lib/ActiveRecord/DriverNotDefined.php         |   6 +-
 lib/ActiveRecord/FinishAtProperty.php         |   2 +-
 lib/ActiveRecord/FinishedAtProperty.php       |   2 +-
 lib/ActiveRecord/HasManyRelation.php          |   7 +-
 lib/ActiveRecord/Model.php                    | 141 +++++++++---------
 lib/ActiveRecord/ModelAlreadyInstantiated.php |  13 +-
 lib/ActiveRecord/ModelCollection.php          |  27 ++--
 lib/ActiveRecord/ModelNotDefined.php          |   9 +-
 lib/ActiveRecord/Query.php                    | 128 ++++++++--------
 lib/ActiveRecord/RecordNotFound.php           |   9 +-
 lib/ActiveRecord/Relation.php                 |   6 +-
 lib/ActiveRecord/RelationCollection.php       |  11 +-
 lib/ActiveRecord/RelationNotDefined.php       |  12 +-
 lib/ActiveRecord/RuntimeActiveRecordCache.php |   4 +-
 lib/ActiveRecord/Schema.php                   |  10 +-
 lib/ActiveRecord/SchemaColumn.php             |  30 ++--
 lib/ActiveRecord/ScopeNotDefined.php          |  14 +-
 lib/ActiveRecord/StartAtProperty.php          |   2 +-
 lib/ActiveRecord/StartedAtProperty.php        |   2 +-
 lib/ActiveRecord/Statement.php                |  44 ++----
 .../StatementInvocationFailed.php             |  16 +-
 lib/ActiveRecord/StatementNotValid.php        |  17 ++-
 lib/ActiveRecord/Table.php                    |  52 +++----
 lib/ActiveRecord/UnableToSetFetchMode.php     |  15 +-
 lib/ActiveRecord/UpdatedAtProperty.php        |   2 +-
 tests/ActiveRecord/ExceptionTest.php          |  27 +++-
 tests/ActiveRecord/ModelTest.php              |   7 +-
 tests/ActiveRecordTest/Sample.php             |   2 +-
 49 files changed, 436 insertions(+), 359 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 22c9fee..fb9b508 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,6 @@ sudo: false
 language: php
 
 php:
-  - 5.6
   - 7.0
   - hhvm
 
@@ -19,5 +18,5 @@ script:
   - mkdir -p build/logs
   - phpunit --coverage-clover build/logs/clover.xml
 
-after_script:
-  - sh -c 'if [ "$TRAVIS_PHP_VERSION" = "5.5" ]; then php vendor/bin/coveralls -v; fi;'
+after_success:
+  - sh -c 'if [ "$TRAVIS_PHP_VERSION" = "7.0" ]; then php vendor/bin/coveralls -v; fi;'
diff --git a/README.md b/README.md
index f66c812..0b19b7a 100644
--- a/README.md
+++ b/README.md
@@ -2138,7 +2138,7 @@ $nodes = ActiveRecord\get_model('nodes');
 
 ## Requirements
 
-The package requires PHP 5.5 or later and the [PDO extension](http://php.net/manual/en/intro.pdo.php).
+The package requires PHP 7.0 or later and the [PDO extension](http://php.net/manual/en/intro.pdo.php).
 
 
 
diff --git a/composer.json b/composer.json
index 948b1f3..fed54b9 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
 	"minimum-stability": "dev",
 
 	"require": {
-		"php": ">=5.6.0",
+		"php": "^7.0",
 		"ext-pdo": "*",
 		"icanboogie/prototype": "^2.3",
 		"icanboogie/inflector": "^1.4",
diff --git a/lib/ActiveRecord.php b/lib/ActiveRecord.php
index 1c6e5b2..01749a9 100644
--- a/lib/ActiveRecord.php
+++ b/lib/ActiveRecord.php
@@ -85,7 +85,7 @@ public function __construct($model = null)
 	 * Properties whose value are instances of the {@link ActiveRecord} class are removed from the
 	 * exported properties.
 	 */
-	public function __sleep()
+	public function __sleep(): array
 	{
 		$properties = parent::__sleep();
 
@@ -108,7 +108,7 @@ public function __sleep()
 	 *
 	 * @return array
 	 */
-	public function __debugInfo()
+	public function __debugInfo(): array
 	{
 		$array = (array) $this;
 
@@ -122,7 +122,7 @@ public function __debugInfo()
 	 *
 	 * @return Model
 	 */
-	protected function get_model()
+	protected function get_model(): Model
 	{
 		return $this->model
 			?: $this->model = ActiveRecord\get_model($this->model_id);
@@ -200,7 +200,7 @@ public function save()
 	 *
 	 * @return array The altered persistent properties
 	 */
-	protected function alter_persistent_properties(array $properties, Model $model)
+	protected function alter_persistent_properties(array $properties, Model $model): array
 	{
 		$schema = $model->extended_schema;
 
@@ -242,7 +242,7 @@ protected function update_primary_key($primary_key)
 	 *
 	 * @throws \Exception in attempt to delete a record from a model which primary key is empty.
 	 */
-	public function delete()
+	public function delete(): bool
 	{
 		$model = $this->model;
 		$primary = $model->primary;
diff --git a/lib/ActiveRecord/ActiveRecordCache.php b/lib/ActiveRecord/ActiveRecordCache.php
index 50caef4..4798709 100644
--- a/lib/ActiveRecord/ActiveRecordCache.php
+++ b/lib/ActiveRecord/ActiveRecordCache.php
@@ -32,14 +32,14 @@ public function store(ActiveRecord $record);
 	 *
 	 * @return ActiveRecord|null
 	 */
-	public function retrieve($key);
+	public function retrieve(int $key);
 
 	/**
 	 * Eliminates an {@link ActiveRecord} instance from the cache.
 	 *
 	 * @param int $key
 	 */
-	public function eliminate($key);
+	public function eliminate(int $key);
 
 	/**
 	 * Clears the cache.
diff --git a/lib/ActiveRecord/ActiveRecordClassNotValid.php b/lib/ActiveRecord/ActiveRecordClassNotValid.php
index 056dea9..125130d 100644
--- a/lib/ActiveRecord/ActiveRecordClassNotValid.php
+++ b/lib/ActiveRecord/ActiveRecordClassNotValid.php
@@ -25,12 +25,12 @@ class ActiveRecordClassNotValid extends \LogicException implements Exception
 	use AccessorTrait;
 
 	/**
-	 * @var string
+	 * @var mixed
 	 */
 	private $class;
 
 	/**
-	 * @return string
+	 * @return mixed
 	 */
 	protected function get_class()
 	{
@@ -38,12 +38,12 @@ protected function get_class()
 	}
 
 	/**
-	 * @param string $class
+	 * @param mixed $class
 	 * @param string|null $message
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($class, $message = null, $code = 500, \Exception $previous = null)
+	public function __construct($class, string $message = null, int $code = 500, \Exception $previous = null)
 	{
 		$this->class = $class;
 
@@ -53,11 +53,11 @@ public function __construct($class, $message = null, $code = 500, \Exception $pr
 	/**
 	 * Formats exception message.
 	 *
-	 * @param string $class
+	 * @param mixed $class
 	 *
 	 * @return string
 	 */
-	protected function format_message($class)
+	protected function format_message($class): string
 	{
 		return format("ActiveRecord class is not valid: %class", [
 
diff --git a/lib/ActiveRecord/BelongsToRelation.php b/lib/ActiveRecord/BelongsToRelation.php
index a32b31e..41639b6 100644
--- a/lib/ActiveRecord/BelongsToRelation.php
+++ b/lib/ActiveRecord/BelongsToRelation.php
@@ -48,6 +48,8 @@ public function __construct(Model $parent, $related, array $options = [])
 
 	/**
 	 * @inheritdoc
+	 *
+	 * @return ActiveRecord|null
 	 */
 	public function __invoke(ActiveRecord $record)
 	{
@@ -66,7 +68,7 @@ public function __invoke(ActiveRecord $record)
 	 *
 	 * @inheritdoc
 	 */
-	protected function alter_prototype(Prototype $prototype, $property)
+	protected function alter_prototype(Prototype $prototype, string $property)
 	{
 		parent::alter_prototype($prototype, $property);
 
@@ -80,7 +82,7 @@ protected function alter_prototype(Prototype $prototype, $property)
 	/**
 	 * @inheritdoc
 	 */
-	protected function resolve_property_name($related)
+	protected function resolve_property_name($related): string
 	{
 		return singularize(parent::resolve_property_name($related));
 	}
diff --git a/lib/ActiveRecord/Connection.php b/lib/ActiveRecord/Connection.php
index cbd4214..af2e245 100644
--- a/lib/ActiveRecord/Connection.php
+++ b/lib/ActiveRecord/Connection.php
@@ -45,7 +45,7 @@ class Connection extends \PDO implements Driver
 	/**
 	 * @return string
 	 */
-	protected function get_id()
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
@@ -64,7 +64,7 @@ protected function get_id()
 	/**
 	 * @return string
 	 */
-	protected function get_table_name_prefix()
+	protected function get_table_name_prefix(): string
 	{
 		return $this->table_name_prefix;
 	}
@@ -79,7 +79,7 @@ protected function get_table_name_prefix()
 	/**
 	 * @return string
 	 */
-	protected function get_charset()
+	protected function get_charset(): string
 	{
 		return $this->charset;
 	}
@@ -94,7 +94,7 @@ protected function get_charset()
 	/**
 	 * @return string
 	 */
-	protected function get_collate()
+	protected function get_collate(): string
 	{
 		return $this->collate;
 	}
@@ -109,7 +109,7 @@ protected function get_collate()
 	/**
 	 * @return string
 	 */
-	protected function get_timezone()
+	protected function get_timezone(): string
 	{
 		return $this->timezone;
 	}
@@ -124,7 +124,7 @@ protected function get_timezone()
 	/**
 	 * @return string
 	 */
-	protected function get_driver_name()
+	protected function get_driver_name(): string
 	{
 		return $this->driver_name;
 	}
@@ -137,7 +137,7 @@ protected function get_driver_name()
 	/**
 	 * @return Driver
 	 */
-	protected function lazy_get_driver()
+	protected function lazy_get_driver(): Driver
 	{
 		return $this->resolve_driver($this->driver_name);
 	}
@@ -170,7 +170,7 @@ protected function lazy_get_driver()
 	 * @param string $password
 	 * @param array $options
 	 */
-	public function __construct($dsn, $username = null, $password = null, $options = [])
+	public function __construct(string $dsn, string $username = null, string $password = null, array $options = [])
 	{
 		unset($this->driver);
 
@@ -186,11 +186,13 @@ public function __construct($dsn, $username = null, $password = null, $options =
 	/**
 	 * Alias to {@link query}.
 	 *
+	 * @param array ...$args
+	 *
 	 * @return Statement
 	 */
-	public function __invoke()
+	public function __invoke(...$args): Statement
 	{
-		return call_user_func_array([ $this, 'query' ], func_get_args());
+		return $this->query(...$args);
 	}
 
 	/**
@@ -200,7 +202,7 @@ public function __invoke()
 	 *
 	 * @return string
 	 */
-	protected function resolve_driver_name($dsn)
+	protected function resolve_driver_name(string $dsn): string
 	{
 		return explode(':', $dsn, 2)[0];
 	}
@@ -214,7 +216,7 @@ protected function resolve_driver_name($dsn)
 	 *
 	 * @throws DriverNotDefined
 	 */
-	protected function resolve_driver_class($driver_name)
+	protected function resolve_driver_class(string $driver_name): string
 	{
 		if (empty(self::$drivers_mapping[$driver_name]))
 		{
@@ -231,7 +233,7 @@ protected function resolve_driver_class($driver_name)
 	 *
 	 * @return Driver
 	 */
-	protected function resolve_driver($driver_name)
+	protected function resolve_driver(string $driver_name): Driver
 	{
 		$driver_class = $this->resolve_driver_class($driver_name);
 
@@ -298,10 +300,7 @@ protected function after_connection()
 	 * Overrides the method to resolve the statement before it is prepared, then set its fetch
 	 * mode and connection.
 	 *
-	 * @param string $statement Query statement.
-	 * @param array $options
-	 *
-	 * @return Statement The prepared statement.
+	 * @inheritdoc
 	 *
 	 * @throws StatementNotValid if the statement cannot be prepared.
 	 */
@@ -325,7 +324,7 @@ public function prepare($statement, $options = [])
 		{
 			$mode = (array) $options['mode'];
 
-			call_user_func_array([ $statement, 'setFetchMode' ], $mode);
+			$statement->mode(...$mode);
 		}
 
 		return $statement;
@@ -339,7 +338,7 @@ public function prepare($statement, $options = [])
 	 *
 	 * @return Statement
 	 */
-	public function query($statement, array $args = [], array $options = [])
+	public function query(string $statement, array $args = [], array $options = []): Statement
 	{
 		$statement = $this->prepare($statement, $options);
 		$statement->execute($args);
@@ -392,7 +391,7 @@ public function exec($statement)
 	 *
 	 * @return string The resolved statement.
 	 */
-	public function resolve_statement($statement)
+	public function resolve_statement(string $statement): string
 	{
 		return strtr($statement, [
 
@@ -438,7 +437,7 @@ public function quote_identifier($identifier)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function cast_value($value, $type = null)
+	public function cast_value($value, string $type = null)
 	{
 		return $this->driver->cast_value($value, $type);
 	}
@@ -448,7 +447,7 @@ public function cast_value($value, $type = null)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function render_column(SchemaColumn $column)
+	public function render_column(SchemaColumn $column): string
 	{
 		return $this->driver->render_column($column);
 	}
@@ -458,7 +457,7 @@ public function render_column(SchemaColumn $column)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function create_table($unprefixed_name, Schema $schema)
+	public function create_table(string $unprefixed_name, Schema $schema)
 	{
 		$this->driver->create_table($unprefixed_name, $schema);
 	}
@@ -468,7 +467,7 @@ public function create_table($unprefixed_name, Schema $schema)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function create_indexes($unprefixed_table_name, Schema $schema)
+	public function create_indexes(string $unprefixed_table_name, Schema $schema)
 	{
 		$this->driver->create_indexes($unprefixed_table_name, $schema);
 	}
@@ -478,7 +477,7 @@ public function create_indexes($unprefixed_table_name, Schema $schema)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function create_unique_indexes($unprefixed_table_name, Schema $schema)
+	public function create_unique_indexes(string $unprefixed_table_name, Schema $schema)
 	{
 		$this->driver->create_unique_indexes($unprefixed_table_name, $schema);
 	}
@@ -488,7 +487,7 @@ public function create_unique_indexes($unprefixed_table_name, Schema $schema)
 	 *
 	 * @codeCoverageIgnore
 	 */
-	public function table_exists($unprefixed_name)
+	public function table_exists(string $unprefixed_name): bool
 	{
 		return $this->driver->table_exists($unprefixed_name);
 	}
diff --git a/lib/ActiveRecord/ConnectionAlreadyEstablished.php b/lib/ActiveRecord/ConnectionAlreadyEstablished.php
index 577caa3..2e8ec24 100644
--- a/lib/ActiveRecord/ConnectionAlreadyEstablished.php
+++ b/lib/ActiveRecord/ConnectionAlreadyEstablished.php
@@ -32,7 +32,7 @@ class ConnectionAlreadyEstablished extends \LogicException implements Exception
 	/**
 	 * @return string
 	 */
-	protected function get_id()
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
@@ -42,7 +42,7 @@ protected function get_id()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($id, $code = 500, \Exception $previous = null)
+	public function __construct(string $id, int $code = 500, \Exception $previous = null)
 	{
 		$this->id = $id;
 
@@ -56,7 +56,7 @@ public function __construct($id, $code = 500, \Exception $previous = null)
 	 *
 	 * @return string
 	 */
-	protected function format_message($id)
+	protected function format_message(string $id): string
 	{
 		return format("Connection already established: %id.", [
 
diff --git a/lib/ActiveRecord/ConnectionCollection.php b/lib/ActiveRecord/ConnectionCollection.php
index 1694cb7..cb6df0d 100644
--- a/lib/ActiveRecord/ConnectionCollection.php
+++ b/lib/ActiveRecord/ConnectionCollection.php
@@ -28,9 +28,12 @@ class ConnectionCollection implements \ArrayAccess, \IteratorAggregate
 	 *
 	 * @var array
 	 */
-	private $definitions;
+	private $definitions = [];
 
-	protected function get_definitions()
+	/**
+	 * @return array
+	 */
+	protected function get_definitions(): array
 	{
 		return $this->definitions;
 	}
@@ -42,7 +45,10 @@ protected function get_definitions()
 	 */
 	private $established = [];
 
-	protected function get_established()
+	/**
+	 * @return Connection[]
+	 */
+	protected function get_established(): array
 	{
 		return $this->established;
 	}
diff --git a/lib/ActiveRecord/ConnectionNotDefined.php b/lib/ActiveRecord/ConnectionNotDefined.php
index 408008e..2b1c9ee 100644
--- a/lib/ActiveRecord/ConnectionNotDefined.php
+++ b/lib/ActiveRecord/ConnectionNotDefined.php
@@ -29,7 +29,10 @@ class ConnectionNotDefined extends \LogicException implements Exception
 	 */
 	private $id;
 
-	protected function get_id()
+	/**
+	 * @return string
+	 */
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
@@ -39,7 +42,7 @@ protected function get_id()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($id, $code = 500, \Exception $previous = null)
+	public function __construct(string $id, int $code = 500, \Exception $previous = null)
 	{
 		$this->id = $id;
 
@@ -53,7 +56,7 @@ public function __construct($id, $code = 500, \Exception $previous = null)
 	 *
 	 * @return string
 	 */
-	protected function format_message($id)
+	protected function format_message(string $id): string
 	{
 		return format("Connection not defined: %id.", [
 
diff --git a/lib/ActiveRecord/ConnectionNotEstablished.php b/lib/ActiveRecord/ConnectionNotEstablished.php
index 182ce7c..f92fd10 100644
--- a/lib/ActiveRecord/ConnectionNotEstablished.php
+++ b/lib/ActiveRecord/ConnectionNotEstablished.php
@@ -27,7 +27,10 @@ class ConnectionNotEstablished extends \RuntimeException implements Exception
 	 */
 	private $id;
 
-	protected function get_id()
+	/**
+	 * @return string
+	 */
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
@@ -38,7 +41,7 @@ protected function get_id()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($id, $message, $code = 500, \Exception $previous = null)
+	public function __construct(string $id, string $message, int $code = 500, \Exception $previous = null)
 	{
 		$this->id = $id;
 
diff --git a/lib/ActiveRecord/ConnectionOptions.php b/lib/ActiveRecord/ConnectionOptions.php
index 60ed8b2..2928b55 100644
--- a/lib/ActiveRecord/ConnectionOptions.php
+++ b/lib/ActiveRecord/ConnectionOptions.php
@@ -65,7 +65,7 @@ final class ConnectionOptions
 	 *
 	 * @return array
 	 */
-	static public function normalize(array $options)
+	static public function normalize(array $options): array
 	{
 		return $options + [
 
diff --git a/lib/ActiveRecord/CreatedAtProperty.php b/lib/ActiveRecord/CreatedAtProperty.php
index c5a786b..6d578f1 100644
--- a/lib/ActiveRecord/CreatedAtProperty.php
+++ b/lib/ActiveRecord/CreatedAtProperty.php
@@ -34,7 +34,7 @@ trait CreatedAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_created_at()
+	protected function get_created_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->created_at);
 	}
diff --git a/lib/ActiveRecord/DateProperty.php b/lib/ActiveRecord/DateProperty.php
index ec0d6ec..e7f2256 100644
--- a/lib/ActiveRecord/DateProperty.php
+++ b/lib/ActiveRecord/DateProperty.php
@@ -34,7 +34,7 @@ trait DateProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_date()
+	protected function get_date(): DateTime
 	{
 		return DateTimePropertySupport::get($this->date);
 	}
diff --git a/lib/ActiveRecord/DateTimeProperty.php b/lib/ActiveRecord/DateTimeProperty.php
index c4ef7c7..a15674b 100644
--- a/lib/ActiveRecord/DateTimeProperty.php
+++ b/lib/ActiveRecord/DateTimeProperty.php
@@ -32,7 +32,7 @@ trait DateTimeProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_datetime()
+	protected function get_datetime(): DateTime
 	{
 		return DateTimePropertySupport::get($this->datetime);
 	}
diff --git a/lib/ActiveRecord/DateTimePropertySupport.php b/lib/ActiveRecord/DateTimePropertySupport.php
index 0742b8a..728737a 100644
--- a/lib/ActiveRecord/DateTimePropertySupport.php
+++ b/lib/ActiveRecord/DateTimePropertySupport.php
@@ -36,7 +36,7 @@ static public function set(&$property, $datetime)
 	 *
 	 * @return DateTime The function always return a {@link DateTime} instance.
 	 */
-	static public function get(&$property)
+	static public function get(&$property): DateTime
 	{
 		if ($property instanceof DateTime)
 		{
diff --git a/lib/ActiveRecord/Driver.php b/lib/ActiveRecord/Driver.php
index f7bd994..b7ed48f 100644
--- a/lib/ActiveRecord/Driver.php
+++ b/lib/ActiveRecord/Driver.php
@@ -42,7 +42,7 @@ public function quote_identifier($identifier);
 	 *
 	 * @return mixed
 	 */
-	public function cast_value($value, $type = null);
+	public function cast_value($value, string $type = null);
 
 	/**
 	 * Renders a column definition.
@@ -51,7 +51,7 @@ public function cast_value($value, $type = null);
 	 *
 	 * @return string
 	 */
-	public function render_column(SchemaColumn $column);
+	public function render_column(SchemaColumn $column): string;
 
 	/**
 	 * Creates a table given a schema.
@@ -63,7 +63,7 @@ public function render_column(SchemaColumn $column);
 	 *
 	 * @throws \Exception
 	 */
-	public function create_table($unprefixed_table_name, Schema $schema);
+	public function create_table(string $unprefixed_table_name, Schema $schema);
 
 	/**
 	 * Creates indexes given a schema.
@@ -75,7 +75,7 @@ public function create_table($unprefixed_table_name, Schema $schema);
 	 *
 	 * @throws \Exception
 	 */
-	public function create_indexes($unprefixed_table_name, Schema $schema);
+	public function create_indexes(string $unprefixed_table_name, Schema $schema);
 
 	/**
 	 * Creates unique indexes given a schema.
@@ -87,7 +87,7 @@ public function create_indexes($unprefixed_table_name, Schema $schema);
 	 *
 	 * @throws \Exception
 	 */
-	public function create_unique_indexes($unprefixed_table_name, Schema $schema);
+	public function create_unique_indexes(string $unprefixed_table_name, Schema $schema);
 
 	/**
 	 * Checks if a specified table exists in the database.
@@ -96,7 +96,7 @@ public function create_unique_indexes($unprefixed_table_name, Schema $schema);
 	 *
 	 * @return bool `true` if the table exists, `false` otherwise.
 	 */
-	public function table_exists($unprefixed_name);
+	public function table_exists(string $unprefixed_name): bool;
 
 	/**
 	 * Optimizes the tables of the database.
diff --git a/lib/ActiveRecord/Driver/BasicDriver.php b/lib/ActiveRecord/Driver/BasicDriver.php
index 594c2fd..412ef36 100644
--- a/lib/ActiveRecord/Driver/BasicDriver.php
+++ b/lib/ActiveRecord/Driver/BasicDriver.php
@@ -89,7 +89,7 @@ public function quote_identifier($identifier)
 	/**
 	 * @inheritdoc
 	 */
-	public function cast_value($value, $type = null)
+	public function cast_value($value, string $type = null)
 	{
 		if ($value instanceof \DateTime)
 		{
@@ -118,7 +118,7 @@ public function cast_value($value, $type = null)
 	 *
 	 * @return string
 	 */
-	protected function resolve_table_name($unprefixed_table_name)
+	protected function resolve_table_name(string $unprefixed_table_name): string
 	{
 		return $this->connection->table_name_prefix . $unprefixed_table_name;
 	}
@@ -130,7 +130,7 @@ protected function resolve_table_name($unprefixed_table_name)
 	 *
 	 * @return string
 	 */
-	protected function resolve_quoted_table_name($unprefixed_table_name)
+	protected function resolve_quoted_table_name(string $unprefixed_table_name): string
 	{
 		return $this->quote_identifier($this->connection->table_name_prefix . $unprefixed_table_name);
 	}
@@ -143,7 +143,7 @@ protected function resolve_quoted_table_name($unprefixed_table_name)
 	 *
 	 * @return string
 	 */
-	protected function resolve_index_name($unprefixed_table_name, $index_id)
+	protected function resolve_index_name(string $unprefixed_table_name, string $index_id): string
 	{
 		return $index_id;
 	}
diff --git a/lib/ActiveRecord/Driver/MySQLDriver.php b/lib/ActiveRecord/Driver/MySQLDriver.php
index d882ca6..aeb4d80 100644
--- a/lib/ActiveRecord/Driver/MySQLDriver.php
+++ b/lib/ActiveRecord/Driver/MySQLDriver.php
@@ -23,7 +23,7 @@ class MySQLDriver extends BasicDriver
 	/**
 	 * @inheritdoc
 	 */
-	public function render_column(SchemaColumn $column)
+	public function render_column(SchemaColumn $column): string
 	{
 		return (string) $column;
 	}
@@ -31,7 +31,7 @@ public function render_column(SchemaColumn $column)
 	/**
 	 * @inheritdoc
 	 */
-	public function create_table($unprefixed_table_name, Schema $schema)
+	public function create_table(string $unprefixed_table_name, Schema $schema)
 	{
 		$statement = $this->render_create_table($unprefixed_table_name, $schema);
 		$this->connection->exec($statement);
@@ -43,7 +43,7 @@ public function create_table($unprefixed_table_name, Schema $schema)
 	/**
 	 * @inheritdoc
 	 */
-	public function create_indexes($unprefixed_table_name, Schema $schema)
+	public function create_indexes(string $unprefixed_table_name, Schema $schema)
 	{
 		$this->create_indexes_of('', $unprefixed_table_name, $schema->indexes);
 	}
@@ -51,7 +51,7 @@ public function create_indexes($unprefixed_table_name, Schema $schema)
 	/**
 	 * @inheritdoc
 	 */
-	public function create_unique_indexes($unprefixed_table_name, Schema $schema)
+	public function create_unique_indexes(string $unprefixed_table_name, Schema $schema)
 	{
 		$this->create_indexes_of('UNIQUE', $unprefixed_table_name, $schema->unique_indexes);
 	}
@@ -59,7 +59,7 @@ public function create_unique_indexes($unprefixed_table_name, Schema $schema)
 	/**
 	 * @inheritdoc
 	 */
-	public function table_exists($unprefixed_name)
+	public function table_exists(string $unprefixed_name): bool
 	{
 		$tables = $this->connection->query('SHOW TABLES')->all(\PDO::FETCH_COLUMN);
 
@@ -84,7 +84,7 @@ public function optimize()
 	 *
 	 * @return string
 	 */
-	protected function render_create_table($unprefixed_table_name, Schema $schema)
+	protected function render_create_table(string $unprefixed_table_name, Schema $schema)
 	{
 		$connection = $this->connection;
 		$quoted_table_name = $this->resolve_quoted_table_name($unprefixed_table_name);
@@ -161,7 +161,7 @@ protected function render_create_table_primary_key(Schema $schema)
 	 * @param string $unprefixed_table_name
 	 * @param array $indexes
 	 */
-	protected function create_indexes_of($type, $unprefixed_table_name, array $indexes)
+	protected function create_indexes_of(string $type, string $unprefixed_table_name, array $indexes)
 	{
 		if (!$indexes)
 		{
diff --git a/lib/ActiveRecord/Driver/SQLiteDriver.php b/lib/ActiveRecord/Driver/SQLiteDriver.php
index e320c41..c21149f 100644
--- a/lib/ActiveRecord/Driver/SQLiteDriver.php
+++ b/lib/ActiveRecord/Driver/SQLiteDriver.php
@@ -22,7 +22,7 @@ class SQLiteDriver extends MySQLDriver
 	/**
 	 * @inheritdoc
 	 */
-	public function render_column(SchemaColumn $column)
+	public function render_column(SchemaColumn $column): string
 	{
 		if ($column->primary && $column->type == SchemaColumn::TYPE_INTEGER)
 		{
@@ -44,7 +44,7 @@ public function render_column(SchemaColumn $column)
 	/**
 	 * @inheritdoc
 	 */
-	protected function render_create_table($unprefixed_table_name, Schema $schema)
+	protected function render_create_table(string $unprefixed_table_name, Schema $schema): string
 	{
 		$quoted_table_name = $this->resolve_quoted_table_name($unprefixed_table_name);
 		$lines = $this->render_create_table_lines($schema);
@@ -56,7 +56,7 @@ protected function render_create_table($unprefixed_table_name, Schema $schema)
 	/**
 	 * @inheritdoc
 	 */
-	public function table_exists($unprefixed_name)
+	public function table_exists(string $unprefixed_name): bool
 	{
 		$name = $this->resolve_table_name($unprefixed_name);
 
@@ -78,7 +78,7 @@ public function optimize()
 	/**
 	 * @inheritdoc
 	 */
-	protected function resolve_index_name($unprefixed_table_name, $index_id)
+	protected function resolve_index_name(string $unprefixed_table_name, string $index_id): string
 	{
 		return $index_id . '_' . substr(sha1($unprefixed_table_name), 0 , 8);
 	}
diff --git a/lib/ActiveRecord/DriverNotDefined.php b/lib/ActiveRecord/DriverNotDefined.php
index 8a885d8..8d61e1c 100644
--- a/lib/ActiveRecord/DriverNotDefined.php
+++ b/lib/ActiveRecord/DriverNotDefined.php
@@ -30,7 +30,7 @@ class DriverNotDefined extends \LogicException implements Exception
 	/**
 	 * @return string
 	 */
-	protected function get_driver_name()
+	protected function get_driver_name(): string
 	{
 		return $this->driver_name;
 	}
@@ -41,7 +41,7 @@ protected function get_driver_name()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($driver_name, $message = null, $code = 500, \Exception $previous = null)
+	public function __construct(string $driver_name, string $message = null, int $code = 500, \Exception $previous = null)
 	{
 		$this->driver_name = $driver_name;
 
@@ -55,7 +55,7 @@ public function __construct($driver_name, $message = null, $code = 500, \Excepti
 	 *
 	 * @return string
 	 */
-	protected function format_message($driver_name)
+	protected function format_message(string $driver_name): string
 	{
 		return "Driver not defined for: $driver_name.";
 	}
diff --git a/lib/ActiveRecord/FinishAtProperty.php b/lib/ActiveRecord/FinishAtProperty.php
index 5d28cc1..d2da5f2 100644
--- a/lib/ActiveRecord/FinishAtProperty.php
+++ b/lib/ActiveRecord/FinishAtProperty.php
@@ -36,7 +36,7 @@ trait FinishAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_finish_at()
+	protected function get_finish_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->finish_at);
 	}
diff --git a/lib/ActiveRecord/FinishedAtProperty.php b/lib/ActiveRecord/FinishedAtProperty.php
index 0845a10..6aa1f57 100644
--- a/lib/ActiveRecord/FinishedAtProperty.php
+++ b/lib/ActiveRecord/FinishedAtProperty.php
@@ -36,7 +36,7 @@ trait FinishedAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_finished_at()
+	protected function get_finished_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->finished_at);
 	}
diff --git a/lib/ActiveRecord/HasManyRelation.php b/lib/ActiveRecord/HasManyRelation.php
index 9192fff..eba1d27 100644
--- a/lib/ActiveRecord/HasManyRelation.php
+++ b/lib/ActiveRecord/HasManyRelation.php
@@ -27,14 +27,17 @@ class HasManyRelation extends Relation
 	 *
 	 * @return Query
 	 */
-	public function __invoke(ActiveRecord $record)
+	public function __invoke(ActiveRecord $record): Query
 	{
 		return $this
 		->resolve_related()
 		->where([ $this->foreign_key => $record->{ $this->local_key }]);
 	}
 
-	protected function resolve_property_name($related)
+	/**
+	 * @inheritdoc
+	 */
+	protected function resolve_property_name($related): string
 	{
 		return pluralize(parent::resolve_property_name($related));
 	}
diff --git a/lib/ActiveRecord/Model.php b/lib/ActiveRecord/Model.php
index 75d0d0d..5573e9c 100644
--- a/lib/ActiveRecord/Model.php
+++ b/lib/ActiveRecord/Model.php
@@ -18,22 +18,21 @@
 /**
  * Base class for activerecord models.
  *
- * @method Query select() select($expression) The method is forwarded to {@link Query::select}.
- * @method Query join() join($expression) The method is forwarded to {@link Query::join}.
- * @method Query where() where($conditions, $conditions_args = null, $_ = null) The method is forwarded to {@link Query::where}.
- * @method Query group() group($group) The method is forwarded to {@link Query::group}.
- * @method Query order() order($order) The method is forwarded to {@link Query::order}.
- * @method Query limit() limit($limit, $offset = null) The method is forwarded to {@link Query::limit}.
- * @method Query offset() offset($offset) The method is forwarded to {@link Query::offset}.
- * @method bool exists() exists($key = null) The method is forwarded to {@link Query::exists}.
- * @method mixed count() count($column = null) The method is forwarded to {@link Query::count}.
- * @method string average() average($column) The method is forwarded to {@link Query::average}.
- * @method string maximum() maximum($column) The method is forwarded to {@link Query::maximum}.
- * @method string minimum() minimum($column) The method is forwarded to {@link Query::minimum}.
- * @method int sum() sum($column) The method is forwarded to {@link Query::sum}.
- * @method array all() all() The method is forwarded to {@link Query::all}.
- * @method ActiveRecord one() one() The method is forwarded to {@link Query::one}.
- * @method ActiveRecord new() new(array $properties = []) Instantiate a new record.
+ * @method Query select(string $expression) The method is forwarded to {@link Query::select}.
+ * @method Query join($expression, array $options = []) The method is forwarded to {@link Query::join}.
+ * @method Query where(...$conditions_and_args) The method is forwarded to {@link Query::where}.
+ * @method Query group(string $group) The method is forwarded to {@link Query::group}.
+ * @method Query order($order) The method is forwarded to {@link Query::order}.
+ * @method Query limit($limit, int $offset = null) The method is forwarded to {@link Query::limit}.
+ * @method Query offset(int $offset) The method is forwarded to {@link Query::offset}.
+ * @method bool exists($key = null) The method is forwarded to {@link Query::exists}.
+ * @method int|array count($column = null) The method is forwarded to {@link Query::count}.
+ * @method number average($column) The method is forwarded to {@link Query::average}.
+ * @method mixed maximum($column) The method is forwarded to {@link Query::maximum}.
+ * @method mixed minimum($column) The method is forwarded to {@link Query::minimum}.
+ * @method number sum($column) The method is forwarded to {@link Query::sum}.
+ * @method array all() The method is forwarded to {@link Query::all}.
+ * @method ActiveRecord|null one() The method is forwarded to {@link Query::one}.
  *
  * @method Model belongs_to() belongs_to(...$args) Adds a _belongs_to_ relation.
  * @method Model has_many() has_many($related, $options = []) Adds a _has_many_ relation.
@@ -44,10 +43,10 @@
  * @property-read string $activerecord_class Class of the active records of the model.
  * @property-read int $count The number of records of the model.
  * @property-read bool $exists Whether the SQL table associated with the model exists.
- * @property-read string $id The identifier of the model.
- * @property-read ActiveRecord $one Retrieve the first record from the mode.
+ * @property-read string|null $id The identifier of the model.
+ * @property-read ActiveRecord|null $one Retrieve the first record from the mode.
  * @property ActiveRecordCache $activerecord_cache The cache use to store activerecords.
- * @property-read Model $parent_model The parent model.
+ * @property-read Model|null $parent_model The parent model.
  * @property-read Relation[] $relations The relations of this model to other models.
  */
 class Model extends Table implements \ArrayAccess
@@ -63,7 +62,10 @@ class Model extends Table implements \ArrayAccess
 	 */
 	private $models;
 
-	protected function get_models()
+	/**
+	 * @return ModelCollection
+	 */
+	protected function get_models(): ModelCollection
 	{
 		return $this->models;
 	}
@@ -73,29 +75,49 @@ protected function get_models()
 	 *
 	 * @var string
 	 */
-	protected $activerecord_class;
+	protected $activerecord_class = ActiveRecord::class;
+
+	/**
+	 * Returns the class of the active records of the model.
+	 *
+	 * @return string
+	 */
+	protected function get_activerecord_class(): string
+	{
+		return $this->activerecord_class;
+	}
 
 	/**
 	 * Attributes of the model.
 	 *
-	 * @var array[string]mixed
+	 * @var array
 	 */
 	protected $attributes;
 
+	/**
+	 * Returns the identifier of the model.
+	 *
+	 * @return string|null
+	 */
+	protected function get_id()
+	{
+		return $this->attributes[self::ID];
+	}
+
 	/**
 	 * The parent model of the model.
 	 *
 	 * The parent model and the {@link parent} may be different if the model does not have a
 	 * schema but inherits it from its parent.
 	 *
-	 * @var Model
+	 * @var Model|null
 	 */
 	protected $parent_model;
 
 	/**
 	 * Return the parent mode.
 	 *
-	 * @return Model
+	 * @return Model|null
 	 */
 	protected function get_parent_model()
 	{
@@ -114,7 +136,7 @@ protected function get_parent_model()
 	 *
 	 * @return RelationCollection
 	 */
-	protected function get_relations()
+	protected function get_relations(): RelationCollection
 	{
 		return $this->relations;
 	}
@@ -126,7 +148,7 @@ protected function get_relations()
 	 *
 	 * @return ActiveRecordCache
 	 */
-	protected function lazy_get_activerecord_cache()
+	protected function lazy_get_activerecord_cache(): ActiveRecordCache
 	{
 		return parent::lazy_get_activerecord_cache();
 	}
@@ -164,7 +186,10 @@ public function __construct(ModelCollection $models, array $attributes)
 	}
 
 	// @codeCoverageIgnoreStart
-	public function __debugInfo()
+	/**
+	 * @inheritdoc
+	 */
+	public function __debugInfo(): array
 	{
 		return [
 
@@ -187,7 +212,7 @@ public function __debugInfo()
 	 *
 	 * @return array
 	 */
-	private function resolve_attributes(array $attributes)
+	private function resolve_attributes(array $attributes): array
 	{
 		$attributes += [
 
@@ -227,7 +252,7 @@ private function resolve_attributes(array $attributes)
 	 *
 	 * @return string
 	 */
-	private function resolve_activerecord_class()
+	private function resolve_activerecord_class(): string
 	{
 		$activerecord_class = $this->attributes[self::ACTIVERECORD_CLASS];
 
@@ -236,7 +261,7 @@ private function resolve_activerecord_class()
 			$activerecord_class = $this->parent->activerecord_class;
 		}
 
-		return $activerecord_class;
+		return $activerecord_class ?: ActiveRecord::class;
 	}
 
 	/**
@@ -272,11 +297,6 @@ private function resolve_relations()
 	 */
 	public function __call($method, $arguments)
 	{
-		if ($method == 'new')
-		{
-			return $this->new_record(...$arguments);
-		}
-
 		if (is_callable([ Query::class, $method ])
 		|| strpos($method, 'filter_by_') === 0
 		|| method_exists($this, 'scope_' . $method))
@@ -311,39 +331,18 @@ public function __get($property)
 		return parent::__get($property);
 	}
 
-	/**
-	 * Returns the identifier of the model.
-	 *
-	 * @return string
-	 */
-	protected function get_id()
-	{
-		return $this->attributes[self::ID];
-	}
-
-	/**
-	 * Returns the class of the active records of the model.
-	 *
-	 * @return string
-	 */
-	protected function get_activerecord_class()
-	{
-		return $this->activerecord_class;
-	}
-
 	/**
 	 * Finds a record or a collection of records.
 	 *
-	 * @param mixed $key A key, multiple keys, or an array of keys.
+	 * @param array $args A key, multiple keys, or an array of keys.
 	 *
 	 * @throws RecordNotFound when the record, or one or more records of the records
 	 * set, could not be found.
 	 *
 	 * @return ActiveRecord|ActiveRecord[] A record or a set of records.
 	 */
-	public function find($key)
+	public function find(...$args)
 	{
-		$args = func_get_args();
 		$n = count($args);
 
 		if (!$n)
@@ -351,7 +350,7 @@ public function find($key)
 			throw new \BadMethodCallException("Expected at least one argument.");
 		}
 
-		if (count($args) == 1)
+		if ($n === 1)
 		{
 			$key = $args[0];
 
@@ -373,7 +372,7 @@ public function find($key)
 	 *
 	 * @return ActiveRecord
 	 */
-	private function find_one($key)
+	private function find_one($key): ActiveRecord
 	{
 		$record = $this->activerecord_cache->retrieve($key);
 
@@ -404,7 +403,7 @@ private function find_one($key)
 	 *
 	 * @return ActiveRecord[]
 	 */
-	private function find_many(array $keys)
+	private function find_many(array $keys): array
 	{
 		$records = array_combine($keys, array_fill(0, count($keys), null));
 		$missing = $records;
@@ -480,7 +479,7 @@ public function save(array $properties, $key = null, array $options = [])
 	 *
 	 * @inheritdoc
 	 */
-	public function delete($key)
+	public function delete($key): bool
 	{
 		$this->activerecord_cache->eliminate($key);
 
@@ -492,7 +491,7 @@ public function delete($key)
 	 *
 	 * @return bool
 	 */
-	protected function get_exists()
+	protected function get_exists(): bool
 	{
 		return $this->exists();
 	}
@@ -502,7 +501,7 @@ protected function get_exists()
 	 *
 	 * @return int
 	 */
-	protected function get_count()
+	protected function get_count(): int
 	{
 		return $this->count();
 	}
@@ -512,7 +511,7 @@ protected function get_count()
 	 *
 	 * @return ActiveRecord[]
 	 */
-	protected function get_all()
+	protected function get_all(): array
 	{
 		return $this->all();
 	}
@@ -520,7 +519,7 @@ protected function get_all()
 	/**
 	 * Returns the first record of the model.
 	 *
-	 * @return ActiveRecord
+	 * @return ActiveRecord|null
 	 */
 	protected function get_one()
 	{
@@ -535,9 +534,9 @@ protected function get_one()
 	 *
 	 * @param string $name Scope name.
 	 *
-	 * @return boolean
+	 * @return bool
 	 */
-	public function has_scope($name)
+	public function has_scope(string $name):bool
 	{
 		return method_exists($this, 'scope_' . $name);
 	}
@@ -553,7 +552,7 @@ public function has_scope($name)
 	 *
 	 * @return Query
 	 */
-	public function scope($scope_name, array $scope_args = [])
+	public function scope(string $scope_name, array $scope_args = []): Query
 	{
 		try
 		{
@@ -604,7 +603,7 @@ public function offsetUnset($key)
 	 *
 	 * @return ActiveRecord
 	 */
-	public function offsetGet($key)
+	public function offsetGet($key): ActiveRecord
 	{
 		return $this->find($key);
 	}
@@ -618,7 +617,7 @@ public function offsetGet($key)
 	 *
 	 * @return ActiveRecord
 	 */
-	protected function new_record(array $properties = [])
+	public function new(array $properties = []): ActiveRecord
 	{
 		$class = $this->activerecord_class;
 
diff --git a/lib/ActiveRecord/ModelAlreadyInstantiated.php b/lib/ActiveRecord/ModelAlreadyInstantiated.php
index 87314c5..0b83a66 100644
--- a/lib/ActiveRecord/ModelAlreadyInstantiated.php
+++ b/lib/ActiveRecord/ModelAlreadyInstantiated.php
@@ -16,7 +16,7 @@
 /**
  * Exception thrown in attempt to set/unset the definition of an already instantiated model.
  *
- * @property-read string $id The identifier of the model.
+ * @property-read string $id Model identifier.
  */
 class ModelAlreadyInstantiated extends \LogicException implements Exception
 {
@@ -27,17 +27,20 @@ class ModelAlreadyInstantiated extends \LogicException implements Exception
 	 */
 	private $id;
 
-	protected function get_id()
+	/**
+	 * @return string
+	 */
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
 
 	/**
-	 * @param string $id
+	 * @param string $id Model identifier.
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($id, $code = 500, \Exception $previous = null)
+	public function __construct(string $id, int $code = 500, \Exception $previous = null)
 	{
 		$this->id = $id;
 
@@ -51,7 +54,7 @@ public function __construct($id, $code = 500, \Exception $previous = null)
 	 *
 	 * @return string
 	 */
-	protected function format_message($id)
+	protected function format_message(string $id): string
 	{
 		return "Model already instantiated: $id.";
 	}
diff --git a/lib/ActiveRecord/ModelCollection.php b/lib/ActiveRecord/ModelCollection.php
index 75f53e2..1ce72a7 100644
--- a/lib/ActiveRecord/ModelCollection.php
+++ b/lib/ActiveRecord/ModelCollection.php
@@ -31,7 +31,10 @@ class ModelCollection implements \ArrayAccess
 	 */
 	protected $instances = [];
 
-	protected function get_instances()
+	/**
+	 * @return Model[]
+	 */
+	protected function get_instances(): array
 	{
 		return $this->instances;
 	}
@@ -43,7 +46,10 @@ protected function get_instances()
 	 */
 	protected $definitions = [];
 
-	protected function get_definitions()
+	/**
+	 * @return array
+	 */
+	protected function get_definitions(): array
 	{
 		return $this->definitions;
 	}
@@ -53,7 +59,10 @@ protected function get_definitions()
 	 */
 	protected $connections;
 
-	protected function get_connections()
+	/**
+	 * @return ConnectionCollection
+	 */
+	protected function get_connections(): ConnectionCollection
 	{
 		return $this->connections;
 	}
@@ -121,7 +130,7 @@ public function offsetSet($id, $definition)
 	 *
 	 * @throws ModelNotDefined when the model is not defined.
 	 */
-	public function offsetGet($id)
+	public function offsetGet($id): Model
 	{
 		if (isset($this->instances[$id]))
 		{
@@ -166,7 +175,7 @@ public function offsetUnset($id)
 	 *
 	 * @return array
 	 */
-	protected function resolve_model_attributes(array $attributes)
+	protected function resolve_model_attributes(array $attributes): array
 	{
 		$attributes += [
 
@@ -200,7 +209,7 @@ protected function resolve_model_attributes(array $attributes)
 	 *
 	 * @return Model
 	 */
-	protected function instantiate_model(array $attributes)
+	protected function instantiate_model(array $attributes): Model
 	{
 		$class = $attributes[Model::CLASSNAME];
 
@@ -210,7 +219,7 @@ protected function instantiate_model(array $attributes)
 	/**
 	 * Install all the models.
 	 *
-	 * @return ModelCollection
+	 * @return $this
 	 */
 	public function install()
 	{
@@ -232,7 +241,7 @@ public function install()
 	/**
 	 * Uninstall all the models.
 	 *
-	 * @return ModelCollection
+	 * @return $this
 	 */
 	public function uninstall()
 	{
@@ -258,7 +267,7 @@ public function uninstall()
 	 * @return array An array of key/value pair where _key_ is a model identifier and
 	 * _value_ `true` if the model is installed, `false` otherwise.
 	 */
-	public function is_installed()
+	public function is_installed(): array
 	{
 		$rc = [];
 
diff --git a/lib/ActiveRecord/ModelNotDefined.php b/lib/ActiveRecord/ModelNotDefined.php
index cf01eb2..e1bac0a 100644
--- a/lib/ActiveRecord/ModelNotDefined.php
+++ b/lib/ActiveRecord/ModelNotDefined.php
@@ -27,7 +27,10 @@ class ModelNotDefined extends \LogicException implements Exception
 	 */
 	private $id;
 
-	protected function get_id()
+	/**
+	 * @return string
+	 */
+	protected function get_id(): string
 	{
 		return $this->id;
 	}
@@ -37,7 +40,7 @@ protected function get_id()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($id, $code = 500, \Exception $previous = null)
+	public function __construct(string $id, int $code = 500, \Exception $previous = null)
 	{
 		$this->id = $id;
 
@@ -51,7 +54,7 @@ public function __construct($id, $code = 500, \Exception $previous = null)
 	 *
 	 * @return string
 	 */
-	protected function format_message($id)
+	protected function format_message(string $id): string
 	{
 		return "Model not defined: $id.";
 	}
diff --git a/lib/ActiveRecord/Query.php b/lib/ActiveRecord/Query.php
index 74291bd..0c86690 100644
--- a/lib/ActiveRecord/Query.php
+++ b/lib/ActiveRecord/Query.php
@@ -67,7 +67,7 @@ class Query implements \IteratorAggregate
 	/**
 	 * @return array
 	 */
-	protected function get_joints()
+	protected function get_joints(): array
 	{
 		return $this->joints;
 	}
@@ -82,7 +82,7 @@ protected function get_joints()
 	/**
 	 * @return array
 	 */
-	protected function get_joints_args()
+	protected function get_joints_args(): array
 	{
 		return $this->joints_args;
 	}
@@ -100,7 +100,7 @@ protected function get_joints_args()
 	 *
 	 * @return array
 	 */
-	protected function get_conditions()
+	protected function get_conditions(): array
 	{
 		return $this->conditions;
 	}
@@ -117,7 +117,7 @@ protected function get_conditions()
 	 *
 	 * @return array
 	 */
-	protected function get_conditions_args()
+	protected function get_conditions_args(): array
 	{
 		return $this->conditions_args;
 	}
@@ -155,7 +155,7 @@ protected function get_conditions_args()
 	 *
 	 * @return array
 	 */
-	protected function get_having_args()
+	protected function get_having_args(): array
 	{
 		return $this->having_args;
 	}
@@ -191,7 +191,7 @@ protected function get_having_args()
 	/**
 	 * @return Model
 	 */
-	protected function get_model()
+	protected function get_model(): Model
 	{
 		return $this->model;
 	}
@@ -202,7 +202,7 @@ protected function get_model()
 	 *
 	 * @return array
 	 */
-	protected function get_args()
+	protected function get_args(): array
 	{
 		return array_merge($this->joints_args, $this->conditions_args, $this->having_args);
 	}
@@ -222,7 +222,7 @@ public function __construct(Model $model)
 	 *
 	 * @inheritdoc
 	 */
-	public function __get($property)
+	public function __get(string $property)
 	{
 		$scopes = $this->get_model_scope();
 
@@ -239,7 +239,7 @@ public function __get($property)
 	 *
 	 * @inheritdoc
 	 */
-	public function __call($method, $arguments)
+	public function __call(string $method, array $arguments)
 	{
 		if ($method === 'and')
 		{
@@ -279,7 +279,7 @@ public function __call($method, $arguments)
 	 *
 	 * @return string
 	 */
-	public function __toString()
+	public function __toString(): string
 	{
 		return $this->resolve_statement
 		(
@@ -294,7 +294,7 @@ public function __toString()
 	 *
 	 * @return string
 	 */
-	protected function render_select()
+	protected function render_select(): string
 	{
 		return 'SELECT ' . ($this->select ? $this->select : '*');
 	}
@@ -306,7 +306,7 @@ protected function render_select()
 	 *
 	 * @return string
 	 */
-	protected function render_from()
+	protected function render_from(): string
 	{
 		return 'FROM {self_and_related}';
 	}
@@ -316,7 +316,7 @@ protected function render_from()
 	 *
 	 * @return string
 	 */
-	protected function render_joints()
+	protected function render_joints(): string
 	{
 		return implode(' ', $this->joints);
 	}
@@ -326,7 +326,7 @@ protected function render_joints()
 	 *
 	 * @return string
 	 */
-	protected function render_main()
+	protected function render_main(): string
 	{
 		$query = '';
 
@@ -381,7 +381,7 @@ protected function render_main()
 	 *
 	 * @return string
 	 */
-	protected function render_order($order)
+	protected function render_order($order): string
 	{
 		if (count($order) == 1)
 		{
@@ -404,12 +404,12 @@ protected function render_order($order)
 	/**
 	 * Render the `LIMIT` and `OFFSET` clauses.
 	 *
-	 * @param int $offset
-	 * @param int $limit
+	 * @param int|null $offset
+	 * @param int|null $limit
 	 *
 	 * @return string
 	 */
-	protected function render_offset_and_limit($offset, $limit)
+	protected function render_offset_and_limit($offset, $limit): string
 	{
 		if ($offset && $limit)
 		{
@@ -434,14 +434,14 @@ protected function render_offset_and_limit($offset, $limit)
 	/**
 	 * Resolve the placeholders of a statement.
 	 *
-	 * Note: Currently, the method simply forwards the statement to the model's
+	 * **Note:** Currently, the method simply forwards the statement to the model's
 	 * resolve_statement() method.
 	 *
 	 * @param string $statement
 	 *
 	 * @return string
 	 */
-	protected function resolve_statement($statement)
+	protected function resolve_statement(string $statement): string
 	{
 		return $this->model->resolve_statement($statement);
 	}
@@ -460,7 +460,7 @@ protected function resolve_statement($statement)
 	 *
 	 * @return array
 	 */
-	protected function get_model_scope()
+	protected function get_model_scope(): array
 	{
 		$class = get_class($this->model);
 
@@ -494,9 +494,9 @@ protected function get_model_scope()
 	 *
 	 * @param string $expression The expression of the `SELECT` clause. e.g. 'nid, title'.
 	 *
-	 * @return Query
+	 * @return $this
 	 */
-	public function select($expression)
+	public function select(string $expression)
 	{
 		$this->select = $expression;
 
@@ -545,15 +545,10 @@ public function select($expression)
 	 * $query->join("INNER JOIN `articles` USING(`nid`)");
 	 * </pre>
 	 *
-	 * @return Query
+	 * @return $this
 	 */
-	public function join($expression, $options = [])
+	public function join($expression, array $options = [])
 	{
-		if (is_string($expression) && $expression{0} == ':')
-		{
-			$expression = $this->model->models[substr($expression, 1)];
-		}
-
 		if ($expression instanceof self)
 		{
 			$this->join_with_query($expression, $options);
@@ -568,6 +563,11 @@ public function join($expression, $options = [])
 			return $this;
 		}
 
+		if (is_string($expression) && $expression{0} == ':')
+		{
+			$expression = $this->model->models[substr($expression, 1)];
+		}
+
 		$this->joints[] = $expression;
 
 		return $this;
@@ -672,7 +672,7 @@ private function join_with_model(Model $model, array $options = [])
 	 *
 	 * @return string
 	 */
-	private function render_join_on($column, $as, Query $query)
+	private function render_join_on(string $column, string $as, Query $query): string
 	{
 		if (isset($query->model->schema[$column]) && isset($this->model->schema[$column]))
 		{
@@ -691,7 +691,7 @@ private function render_join_on($column, $as, Query $query)
 	 *
 	 * @return array An array made of the condition string and its arguments.
 	 */
-	private function deferred_parse_conditions(...$conditions_and_args)
+	private function deferred_parse_conditions(...$conditions_and_args): array
 	{
 		$conditions = array_shift($conditions_and_args);
 		$args = $conditions_and_args;
@@ -775,13 +775,13 @@ private function deferred_parse_conditions(...$conditions_and_args)
 	 * @param string $filter
 	 * @param array $conditions_args
 	 *
-	 * @return Query
+	 * @return $this
 	 */
-	private function dynamic_filter($filter, array $conditions_args = [])
+	private function dynamic_filter(string $filter, array $conditions_args = [])
 	{
 		$conditions = explode('_and_', $filter);
 
-		return $this->where(array_combine($conditions, $conditions_args));
+		return $this->and(array_combine($conditions, $conditions_args));
 	}
 
 	/**
@@ -835,7 +835,7 @@ private function dynamic_filter($filter, array $conditions_args = [])
 	 *
 	 * @param mixed ...$conditions_and_args
 	 *
-	 * @return Query
+	 * @return $this
 	 */
 	public function where(...$conditions_and_args)
 	{
@@ -861,7 +861,7 @@ public function where(...$conditions_and_args)
 	 * 'weight, date DESC', or field to order with, in which case `$field_values` is required.
 	 * @param array $field_values Values of the field specified by `$order_or_field_name`.
 	 *
-	 * @return Query
+	 * @return $this
 	 */
 	public function order($order_or_field_name, $field_values = null)
 	{
@@ -875,9 +875,9 @@ public function order($order_or_field_name, $field_values = null)
 	 *
 	 * @param string $group
 	 *
-	 * @return Query
+	 * @return $this
 	 */
-	public function group($group)
+	public function group(string $group)
 	{
 		$this->group = $group;
 
@@ -889,7 +889,7 @@ public function group($group)
 	 *
 	 * @param mixed ...$conditions_and_args
 	 *
-	 * @return Query
+	 * @return $this
 	 */
 	public function having(...$conditions_and_args)
 	{
@@ -904,13 +904,13 @@ public function having(...$conditions_and_args)
 	/**
 	 * Define the offset of the `LIMIT` clause.
 	 *
-	 * @param $offset
+	 * @param int $offset
 	 *
-	 * @return Query
+	 * @return $this
 	 */
-	public function offset($offset)
+	public function offset(int $offset)
 	{
-		$this->offset = (int) $offset;
+		$this->offset = $offset;
 
 		return $this;
 	}
@@ -959,9 +959,9 @@ public function limit($limit)
 	 *
 	 * @see http://www.php.net/manual/en/pdostatement.setfetchmode.php
 	 */
-	public function mode($mode)
+	public function mode(...$mode)
 	{
-		$this->mode = func_get_args();
+		$this->mode = $mode;
 
 		return $this;
 	}
@@ -974,7 +974,7 @@ public function mode($mode)
 	 *
 	 * @return Statement
 	 */
-	protected function prepare()
+	protected function prepare(): Statement
 	{
 		return $this->model->connection->prepare((string) $this);
 	}
@@ -984,7 +984,7 @@ protected function prepare()
 	 *
 	 * @return Statement
 	 */
-	protected function get_prepared()
+	protected function get_prepared(): Statement
 	{
 		return $this->prepare();
 	}
@@ -994,7 +994,7 @@ protected function get_prepared()
 	 *
 	 * @return Statement
 	 */
-	public function query()
+	public function query(): Statement
 	{
 		$statement = $this->prepare();
 		$statement->execute($this->args);
@@ -1013,7 +1013,7 @@ public function query()
 	 *
 	 * @return array
 	 */
-	private function resolve_fetch_mode(...$mode)
+	private function resolve_fetch_mode(...$mode): array
 	{
 		if ($mode)
 		{
@@ -1056,7 +1056,7 @@ public function all(...$mode)
 	 *
 	 * @return array
 	 */
-	protected function get_all()
+	protected function get_all(): array
 	{
 		return $this->all();
 	}
@@ -1108,7 +1108,7 @@ protected function get_one()
 	 *
 	 * @return array
 	 */
-	protected function get_pairs()
+	protected function get_pairs(): array
 	{
 		return $this->all(\PDO::FETCH_KEY_PAIR);
 	}
@@ -1116,7 +1116,7 @@ protected function get_pairs()
 	/**
 	 * Return the value of the first column of the first row.
 	 *
-	 * @return string
+	 * @return mixed
 	 */
 	protected function get_rc()
 	{
@@ -1216,11 +1216,11 @@ protected function get_exists()
 	 * Handle all the computations.
 	 *
 	 * @param string $method
-	 * @param string $column
+	 * @param string|null $column
 	 *
 	 * @return int|array
 	 */
-	private function compute($method, $column)
+	private function compute(string $method, string $column = null)
 	{
 		$query = 'SELECT ';
 
@@ -1270,7 +1270,7 @@ public function count($column = null)
 	 *
 	 * @return int
 	 */
-	protected function get_count()
+	protected function get_count(): int
 	{
 		return $this->count();
 	}
@@ -1280,9 +1280,9 @@ protected function get_count()
 	 *
 	 * @param string $column
 	 *
-	 * @return int
+	 * @return number
 	 */
-	public function average($column)
+	public function average(string $column)
 	{
 		return $this->compute('AVG', $column);
 	}
@@ -1292,9 +1292,9 @@ public function average($column)
 	 *
 	 * @param string $column
 	 *
-	 * @return int
+	 * @return mixed
 	 */
-	public function minimum($column)
+	public function minimum(string $column)
 	{
 		return $this->compute('MIN', $column);
 	}
@@ -1304,9 +1304,9 @@ public function minimum($column)
 	 *
 	 * @param string $column
 	 *
-	 * @return int
+	 * @return mixed
 	 */
-	public function maximum($column)
+	public function maximum(string $column)
 	{
 		return $this->compute('MAX', $column);
 	}
@@ -1316,9 +1316,9 @@ public function maximum($column)
 	 *
 	 * @param string $column
 	 *
-	 * @return int
+	 * @return number
 	 */
-	public function sum($column)
+	public function sum(string $column)
 	{
 		return $this->compute('SUM', $column);
 	}
diff --git a/lib/ActiveRecord/RecordNotFound.php b/lib/ActiveRecord/RecordNotFound.php
index 9abda0a..c1f4e7e 100644
--- a/lib/ActiveRecord/RecordNotFound.php
+++ b/lib/ActiveRecord/RecordNotFound.php
@@ -30,9 +30,12 @@ class RecordNotFound extends \LogicException implements Exception
 	 *
 	 * @var ActiveRecord[]
 	 */
-	private $records;
+	private $records = [];
 
-	protected function get_records()
+	/**
+	 * @return ActiveRecord[]
+	 */
+	protected function get_records(): array
 	{
 		return $this->records;
 	}
@@ -45,7 +48,7 @@ protected function get_records()
 	 * @param int $code Defaults to 404.
 	 * @param \Exception $previous Previous exception.
 	 */
-	public function __construct($message, array $records = [], $code = 404, \Exception $previous = null)
+	public function __construct(string $message, array $records = [], int $code = 404, \Exception $previous = null)
 	{
 		$this->records = $records;
 
diff --git a/lib/ActiveRecord/Relation.php b/lib/ActiveRecord/Relation.php
index c99c0da..30b6259 100644
--- a/lib/ActiveRecord/Relation.php
+++ b/lib/ActiveRecord/Relation.php
@@ -148,7 +148,7 @@ abstract public function __invoke(ActiveRecord $record);
 	 * @param Prototype $prototype The active record prototype.
 	 * @param string $property The name of the property.
 	 */
-	protected function alter_prototype(Prototype $prototype, $property)
+	protected function alter_prototype(Prototype $prototype, string $property)
 	{
 		$prototype["get_$property"] = $this;
 	}
@@ -181,7 +181,7 @@ protected function resolve_activerecord_class(Model $model)
 	 *
 	 * @return string
 	 */
-	protected function resolve_property_name($related)
+	protected function resolve_property_name($related): string
 	{
 		$related_id = $related instanceof Model ? $related->id : $related;
 		$parts = explode('.', $related_id);
@@ -194,7 +194,7 @@ protected function resolve_property_name($related)
 	 *
 	 * @return Model
 	 */
-	protected function resolve_related()
+	protected function resolve_related(): Model
 	{
 		$related = $this->related;
 
diff --git a/lib/ActiveRecord/RelationCollection.php b/lib/ActiveRecord/RelationCollection.php
index 2d5343d..5a960f6 100644
--- a/lib/ActiveRecord/RelationCollection.php
+++ b/lib/ActiveRecord/RelationCollection.php
@@ -30,7 +30,10 @@ class RelationCollection implements \ArrayAccess
 	 */
 	protected $model;
 
-	protected function get_model()
+	/**
+	 * @return Model
+	 */
+	protected function get_model(): Model
 	{
 		return $this->model;
 	}
@@ -73,7 +76,7 @@ public function offsetExists($relation_name)
 	 *
 	 * @throws RelationNotDefined if the relation is not defined.
 	 */
-	public function offsetGet($relation_name)
+	public function offsetGet($relation_name): Relation
 	{
 		if (!$this->offsetExists($relation_name))
 		{
@@ -123,7 +126,7 @@ public function offsetUnset($relation_name)
 	 *
 	 * @return Model
 	 */
-	public function belongs_to($belongs_to)
+	public function belongs_to($belongs_to): Model
 	{
 		if (func_num_args() > 1)
 		{
@@ -169,7 +172,7 @@ public function belongs_to($belongs_to)
 	 *
 	 * @see HasManyRelation
 	 */
-	public function has_many($related, array $options = [])
+	public function has_many($related, array $options = []): Model
 	{
 		if (is_array($related))
 		{
diff --git a/lib/ActiveRecord/RelationNotDefined.php b/lib/ActiveRecord/RelationNotDefined.php
index d4503ee..fde9c65 100644
--- a/lib/ActiveRecord/RelationNotDefined.php
+++ b/lib/ActiveRecord/RelationNotDefined.php
@@ -31,7 +31,10 @@ class RelationNotDefined extends OffsetNotDefined implements Exception
 	 */
 	private $relation_name;
 
-	protected function get_relation_name()
+	/**
+	 * @return string
+	 */
+	protected function get_relation_name(): string
 	{
 		return $this->relation_name;
 	}
@@ -43,7 +46,10 @@ protected function get_relation_name()
 	 */
 	private $collection;
 
-	protected function get_collection()
+	/**
+	 * @return RelationCollection
+	 */
+	protected function get_collection(): RelationCollection
 	{
 		return $this->collection;
 	}
@@ -54,7 +60,7 @@ protected function get_collection()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($relation_name, RelationCollection $collection, $code = 500, \Exception $previous = null)
+	public function __construct(string $relation_name, RelationCollection $collection, int $code = 500, \Exception $previous = null)
 	{
 		$this->relation_name = $relation_name;
 		$this->collection = $collection;
diff --git a/lib/ActiveRecord/RuntimeActiveRecordCache.php b/lib/ActiveRecord/RuntimeActiveRecordCache.php
index b9a22d0..b81102c 100644
--- a/lib/ActiveRecord/RuntimeActiveRecordCache.php
+++ b/lib/ActiveRecord/RuntimeActiveRecordCache.php
@@ -43,7 +43,7 @@ public function store(ActiveRecord $record)
 	/**
 	 * @inheritdoc
 	 */
-	public function retrieve($key)
+	public function retrieve(int $key)
 	{
 		if (empty($this->records[$key]))
 		{
@@ -56,7 +56,7 @@ public function retrieve($key)
 	/**
 	 * @inheritdoc
 	 */
-	public function eliminate($key)
+	public function eliminate(int $key)
 	{
 		unset($this->records[$key]);
 	}
diff --git a/lib/ActiveRecord/Schema.php b/lib/ActiveRecord/Schema.php
index cea307e..6d7c851 100644
--- a/lib/ActiveRecord/Schema.php
+++ b/lib/ActiveRecord/Schema.php
@@ -35,7 +35,7 @@ class Schema implements \ArrayAccess, \IteratorAggregate
 	/**
 	 * @return SchemaColumn[]
 	 */
-	protected function get_columns()
+	protected function get_columns(): array
 	{
 		return $this->columns;
 	}
@@ -72,7 +72,7 @@ protected function get_primary()
 	 *
 	 * @return array
 	 */
-	protected function get_indexes()
+	protected function get_indexes(): array
 	{
 		return $this->collect_indexes_by_type('indexed');
 	}
@@ -82,7 +82,7 @@ protected function get_indexes()
 	 *
 	 * @return array
 	 */
-	protected function get_unique_indexes()
+	protected function get_unique_indexes(): array
 	{
 		return $this->collect_indexes_by_type('unique');
 	}
@@ -177,7 +177,7 @@ public function getIterator()
 	 *
 	 * @return array
 	 */
-	private function collect_indexes_by_type($type)
+	private function collect_indexes_by_type(string $type): array
 	{
 		$indexes = [];
 
@@ -203,7 +203,7 @@ private function collect_indexes_by_type($type)
 	 *
 	 * @return array
 	 */
-	public function filter(array $values)
+	public function filter(array $values): array
 	{
 		return array_intersect_key($values, $this->columns);
 	}
diff --git a/lib/ActiveRecord/SchemaColumn.php b/lib/ActiveRecord/SchemaColumn.php
index 2dedfd2..60e0498 100644
--- a/lib/ActiveRecord/SchemaColumn.php
+++ b/lib/ActiveRecord/SchemaColumn.php
@@ -72,7 +72,10 @@ class SchemaColumn
 	 */
 	protected $primary = false;
 
-	protected function get_primary()
+	/**
+	 * @return bool
+	 */
+	protected function get_primary(): bool
 	{
 		return $this->primary;
 	}
@@ -155,7 +158,7 @@ public function __construct(array $options)
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_type()
+	protected function get_formatted_type(): string
 	{
 		$rc = '';
 
@@ -212,7 +215,7 @@ protected function get_formatted_type()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_default()
+	protected function get_formatted_default(): string
 	{
 		$default = $this->default;
 
@@ -238,7 +241,7 @@ protected function get_formatted_default()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_attributes()
+	protected function get_formatted_attributes(): string
 	{
 		return $this->unsigned ? 'UNSIGNED' : '';
 	}
@@ -248,7 +251,7 @@ protected function get_formatted_attributes()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_null()
+	protected function get_formatted_null(): string
 	{
 		return $this->null ? 'NULL' : 'NOT NULL';
 	}
@@ -258,7 +261,7 @@ protected function get_formatted_null()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_index()
+	protected function get_formatted_index(): string
 	{
 		return implode(' ', array_filter([
 
@@ -273,7 +276,7 @@ protected function get_formatted_index()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_comment()
+	protected function get_formatted_comment(): string
 	{
 		return $this->comment ? "`$this->comment`" : '';
 	}
@@ -283,7 +286,7 @@ protected function get_formatted_comment()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_charset()
+	protected function get_formatted_charset(): string
 	{
 		$charset = $this->charset;
 
@@ -302,7 +305,7 @@ protected function get_formatted_charset()
 	 *
 	 * @return string
 	 */
-	protected function get_formatted_auto_increment()
+	protected function get_formatted_auto_increment(): string
 	{
 		return $this->auto_increment ? 'AUTO_INCREMENT' : '';
 	}
@@ -312,7 +315,7 @@ protected function get_formatted_auto_increment()
 	 *
 	 * @return bool
 	 */
-	protected function get_is_serial()
+	protected function get_is_serial(): bool
 	{
 		return $this->type == self::TYPE_INTEGER && !$this->null && $this->auto_increment && $this->primary;
 	}
@@ -322,7 +325,7 @@ protected function get_is_serial()
 	 *
 	 * @return string
 	 */
-	public function render()
+	public function render(): string
 	{
 		return implode(' ', array_filter([
 
@@ -337,7 +340,10 @@ public function render()
 		]));
 	}
 
-	public function __toString()
+	/**
+	 * @return string
+	 */
+	public function __toString(): string
 	{
 		return (string) $this->render();
 	}
diff --git a/lib/ActiveRecord/ScopeNotDefined.php b/lib/ActiveRecord/ScopeNotDefined.php
index 1d25e56..d9df930 100644
--- a/lib/ActiveRecord/ScopeNotDefined.php
+++ b/lib/ActiveRecord/ScopeNotDefined.php
@@ -30,7 +30,10 @@ class ScopeNotDefined extends \LogicException implements Exception
 	 */
 	private $scope_name;
 
-	protected function get_scope_name()
+	/**
+	 * @return string
+	 */
+	protected function get_scope_name(): string
 	{
 		return $this->scope_name;
 	}
@@ -42,7 +45,10 @@ protected function get_scope_name()
 	 */
 	private $model;
 
-	protected function get_model()
+	/**
+	 * @return Model
+	 */
+	protected function get_model(): Model
 	{
 		return $this->model;
 	}
@@ -55,7 +61,7 @@ protected function get_model()
 	 * @param int $code Default to 404.
 	 * @param \Exception $previous Previous exception.
 	 */
-	public function __construct($scope_name, Model $model, $code = 500, \Exception $previous = null)
+	public function __construct(string $scope_name, Model $model, int $code = 500, \Exception $previous = null)
 	{
 		$this->scope_name = $scope_name;
 		$this->model = $model;
@@ -71,7 +77,7 @@ public function __construct($scope_name, Model $model, $code = 500, \Exception $
 	 *
 	 * @return string
 	 */
-	protected function format_message($scope_name, Model $model)
+	protected function format_message(string $scope_name, Model $model): string
 	{
 		return "Unknown scope `{$scope_name}` for model `{$model->unprefixed_name}`.";
 	}
diff --git a/lib/ActiveRecord/StartAtProperty.php b/lib/ActiveRecord/StartAtProperty.php
index 89af1ae..e97564c 100644
--- a/lib/ActiveRecord/StartAtProperty.php
+++ b/lib/ActiveRecord/StartAtProperty.php
@@ -36,7 +36,7 @@ trait StartAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_start_at()
+	protected function get_start_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->start_at);
 	}
diff --git a/lib/ActiveRecord/StartedAtProperty.php b/lib/ActiveRecord/StartedAtProperty.php
index 76c59f8..b75642a 100644
--- a/lib/ActiveRecord/StartedAtProperty.php
+++ b/lib/ActiveRecord/StartedAtProperty.php
@@ -36,7 +36,7 @@ trait StartedAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_started_at()
+	protected function get_started_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->started_at);
 	}
diff --git a/lib/ActiveRecord/Statement.php b/lib/ActiveRecord/Statement.php
index 8722d3c..172c9b9 100644
--- a/lib/ActiveRecord/Statement.php
+++ b/lib/ActiveRecord/Statement.php
@@ -34,11 +34,17 @@ class Statement extends \PDOStatement
 	 */
 	private $connection;
 
-	protected function get_connection()
+	/**
+	 * @return Connection
+	 */
+	protected function get_connection(): Connection
 	{
 		return $this->connection;
 	}
 
+	/**
+	 * @param Connection $connection
+	 */
 	protected function set_connection(Connection $connection)
 	{
 		$this->connection = $connection;
@@ -52,12 +58,12 @@ protected function set_connection(Connection $connection)
 	 *     $statement(1, 2, 3);
 	 *     $statement([ 1, 2, 3 ]);
 	 *
+	 * @param array $args
+	 *
 	 * @return $this
 	 */
-	public function __invoke()
+	public function __invoke(...$args)
 	{
-		$args = func_get_args();
-
 		if ($args && is_array($args[0]))
 		{
 			$args = $args[0];
@@ -74,7 +80,7 @@ public function __invoke()
 	/**
 	 * Return the {@link queryString} property of the statement.
 	 */
-	public function __toString()
+	public function __toString(): string
 	{
 		return $this->queryString;
 	}
@@ -159,27 +165,9 @@ protected function get_one()
 	}
 
 	/**
-	 * Fetches a column of the first row of the result set and closes the cursor.
-	 *
-	 * @param int $column_number
-	 *
-	 * @return string
+	 * Fetches the first column of the first row of the result set and closes the cursor.
 	 *
-	 * @see PDOStatement::fetchColumn()
-	 *
-	 * @deprecated
-	 */
-	public function fetchColumnAndClose($column_number = 0)
-	{
-		$rc = $this->fetchColumn($column_number);
-
-		$this->closeCursor();
-
-		return $rc;
-	}
-
-	/**
-	 * Alias for `fetchColumnAndClose()`.
+	 * @return mixed
 	 */
 	protected function get_rc()
 	{
@@ -197,7 +185,7 @@ protected function get_rc()
 	 *
 	 * @return array
 	 */
-	public function all(...$mode)
+	public function all(...$mode): array
 	{
 		return $this->fetchAll(...$mode);
 	}
@@ -205,7 +193,7 @@ public function all(...$mode)
 	/**
 	 * Alias for `all()`.
 	 */
-	protected function get_all()
+	protected function get_all(): array
 	{
 		return $this->fetchAll();
 	}
@@ -216,7 +204,7 @@ protected function get_all()
 	 * @return array An array of key/value pairs, where _key_ is the value of the first
 	 * column and _value_ the value of the second column.
 	 */
-	protected function get_pairs()
+	protected function get_pairs(): array
 	{
 		return $this->fetchAll(\PDO::FETCH_KEY_PAIR);
 	}
diff --git a/lib/ActiveRecord/StatementInvocationFailed.php b/lib/ActiveRecord/StatementInvocationFailed.php
index 9b21861..81bf9c1 100644
--- a/lib/ActiveRecord/StatementInvocationFailed.php
+++ b/lib/ActiveRecord/StatementInvocationFailed.php
@@ -28,7 +28,10 @@ class StatementInvocationFailed extends \LogicException implements Exception
 	 */
 	private $statement;
 
-	protected function get_statement()
+	/**
+	 * @return Statement
+	 */
+	protected function get_statement(): Statement
 	{
 		return $this->statement;
 	}
@@ -36,9 +39,12 @@ protected function get_statement()
 	/**
 	 * @var array
 	 */
-	private $args;
+	private $args = [];
 
-	protected function get_args()
+	/**
+	 * @return array
+	 */
+	protected function get_args(): array
 	{
 		return $this->args;
 	}
@@ -50,7 +56,7 @@ protected function get_args()
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct(Statement $statement, array $args, $message = null, $code = 500, \Exception $previous = null)
+	public function __construct(Statement $statement, array $args, string $message = null, int $code = 500, \Exception $previous = null)
 	{
 		$this->statement = $statement;
 		$this->args = $args;
@@ -66,7 +72,7 @@ public function __construct(Statement $statement, array $args, $message = null,
 	 *
 	 * @return string
 	 */
-	private function format_message(Statement $statement, array $args)
+	private function format_message(Statement $statement, array $args): string
 	{
 		return "Statement execution failed: {$statement->queryString}, with: " . json_encode($args);
 	}
diff --git a/lib/ActiveRecord/StatementNotValid.php b/lib/ActiveRecord/StatementNotValid.php
index 32cc9ba..5ad9074 100644
--- a/lib/ActiveRecord/StatementNotValid.php
+++ b/lib/ActiveRecord/StatementNotValid.php
@@ -25,10 +25,13 @@ class StatementNotValid extends \RuntimeException implements Exception
 	use AccessorTrait;
 
 	/**
-	 * @var string
+	 * @var Statement|string
 	 */
 	private $statement;
 
+	/**
+	 * @return Statement|string
+	 */
 	protected function get_statement()
 	{
 		return $this->statement;
@@ -37,25 +40,31 @@ protected function get_statement()
 	/**
 	 * @var array
 	 */
-	private $args;
+	private $args = [];
 
+	/**
+	 * @return array
+	 */
 	protected function get_args()
 	{
 		return $this->args;
 	}
 
 	/**
-	 * @var \PDOException
+	 * @var \PDOException|null
 	 */
 	private $original;
 
+	/**
+	 * @return \PDOException|null
+	 */
 	protected function get_original()
 	{
 		return $this->original;
 	}
 
 	/**
-	 * @param array|string $statement
+	 * @param Statement|array|string $statement
 	 * @param int $code
 	 * @param \PDOException|null $original
 	 */
diff --git a/lib/ActiveRecord/Table.php b/lib/ActiveRecord/Table.php
index 01dbeb4..b3d550e 100644
--- a/lib/ActiveRecord/Table.php
+++ b/lib/ActiveRecord/Table.php
@@ -66,7 +66,7 @@ class Table extends Prototyped
 	 *
 	 * @return Connection
 	 */
-	protected function get_connection()
+	protected function get_connection(): Connection
 	{
 		return $this->connection;
 	}
@@ -81,7 +81,7 @@ protected function get_connection()
 	/**
 	 * @return string
 	 */
-	protected function get_name()
+	protected function get_name(): string
 	{
 		return $this->name;
 	}
@@ -96,7 +96,7 @@ protected function get_name()
 	/**
 	 * @return string
 	 */
-	protected function get_unprefixed_name()
+	protected function get_unprefixed_name(): string
 	{
 		return $this->unprefixed_name;
 	}
@@ -129,7 +129,7 @@ protected function get_primary()
 	/**
 	 * @return string
 	 */
-	protected function get_alias()
+	protected function get_alias(): string
 	{
 		return $this->alias;
 	}
@@ -144,7 +144,7 @@ protected function get_alias()
 	/**
 	 * @return Schema
 	 */
-	protected function get_schema()
+	protected function get_schema(): Schema
 	{
 		return $this->schema;
 	}
@@ -159,7 +159,7 @@ protected function get_schema()
 	/**
 	 * @return array
 	 */
-	protected function get_schema_options()
+	protected function get_schema_options(): array
 	{
 		return $this->schema_options;
 	}
@@ -168,12 +168,12 @@ protected function get_schema_options()
 	 * The parent is used when the table is in a hierarchy, which is the case if the table
 	 * extends another table.
 	 *
-	 * @var Table
+	 * @var Table|null
 	 */
 	protected $parent;
 
 	/**
-	 * @return Table
+	 * @return Table|null
 	 */
 	protected function get_parent()
 	{
@@ -193,7 +193,7 @@ protected function get_parent()
 	/**
 	 * @return string
 	 */
-	protected function lazy_get_update_join()
+	protected function lazy_get_update_join(): string
 	{
 		$join = '';
 		$parent = $this->parent;
@@ -220,7 +220,7 @@ protected function lazy_get_update_join()
 	/**
 	 * @return string
 	 */
-	protected function lazy_get_select_join()
+	protected function lazy_get_select_join(): string
 	{
 		$join = "`{$this->alias}`" . $this->update_join;
 
@@ -245,7 +245,7 @@ protected function lazy_get_select_join()
 	 *
 	 * @return Schema
 	 */
-	protected function lazy_get_extended_schema()
+	protected function lazy_get_extended_schema(): Schema
 	{
 		$table = $this;
 		$options = [];
@@ -304,15 +304,15 @@ public function __construct(array $attributes)
 	/**
 	 * Alias to {@link query()}.
 	 *
-	 * @param string $query
+	 * @param string $statement
 	 * @param array $args
 	 * @param array $options
 	 *
 	 * @return Statement
 	 */
-	public function __invoke($query, array $args = [], array $options = [])
+	public function __invoke(string $statement, array $args = [], array $options = []): Statement
 	{
-		return $this->query($query, $args, $options);
+		return $this->query($statement, $args, $options);
 	}
 
 	/**
@@ -502,7 +502,7 @@ public function uninstall()
 	 *
 	 * @return bool `true` if the table exists, `false` otherwise.
 	 */
-	public function is_installed()
+	public function is_installed(): bool
 	{
 		return $this->connection->table_exists($this->unprefixed_name);
 	}
@@ -528,7 +528,7 @@ public function is_installed()
 	 *
 	 * @return string
 	 */
-	public function resolve_statement($statement)
+	public function resolve_statement($statement): string
 	{
 		$primary = $this->primary;
 		$primary = is_array($primary) ? '__multicolumn_primary__' . implode('_', $primary) : $primary;
@@ -554,7 +554,7 @@ public function resolve_statement($statement)
 	 *
 	 * @return Statement
 	 */
-	public function prepare($query, $options = [])
+	public function prepare($query, $options = []): Statement
 	{
 		$query = $this->resolve_statement($query);
 
@@ -569,7 +569,7 @@ public function prepare($query, $options = [])
 	 *
 	 * @return string
 	 */
-	public function quote($string, $parameter_type = \PDO::PARAM_STR)
+	public function quote(string $string, int $parameter_type = \PDO::PARAM_STR): string
 	{
 		return $this->connection->quote($string, $parameter_type);
 	}
@@ -579,15 +579,15 @@ public function quote($string, $parameter_type = \PDO::PARAM_STR)
 	 *
 	 * The statement is prepared by the {@link prepare()} method before it is executed.
 	 *
-	 * @param string $query
+	 * @param string $statement
 	 * @param array $args
 	 * @param array $options
 	 *
 	 * @return mixed
 	 */
-	public function execute($query, array $args = [], array $options = [])
+	public function execute(string $statement, array $args = [], array $options = [])
 	{
-		$statement = $this->prepare($query, $options);
+		$statement = $this->prepare($statement, $options);
 
 		return $statement($args);
 	}
@@ -603,7 +603,7 @@ public function execute($query, array $args = [], array $options = [])
 	 *
 	 * @return Statement
 	 */
-	public function query($query, array $args = [], array $options = [])
+	public function query(string $query, array $args = [], array $options = [])
 	{
 		$statement = $this->prepare($this->resolve_statement($query), $options);
 		$statement($args);
@@ -615,11 +615,11 @@ public function query($query, array $args = [], array $options = [])
 	 * Filters mass assignment values.
 	 *
 	 * @param array $values
-	 * @param bool|false $extended
+	 * @param bool $extended
 	 *
 	 * @return array
 	 */
-	protected function filter_values(array $values, $extended = false)
+	protected function filter_values(array $values, bool $extended = false): array
 	{
 		$filtered = [];
 		$holders = [];
@@ -914,7 +914,7 @@ public function update(array $values, $key)
 	 *
 	 * @return bool
 	 */
-	public function delete($key)
+	public function delete($key): bool
 	{
 		if ($this->parent)
 		{
@@ -973,7 +973,7 @@ public function truncate()
 	 *
 	 * @return mixed
 	 */
-	public function drop(array $options=[])
+	public function drop(array $options = [])
 	{
 		$query = 'DROP TABLE ';
 
diff --git a/lib/ActiveRecord/UnableToSetFetchMode.php b/lib/ActiveRecord/UnableToSetFetchMode.php
index 51ec83a..946cd87 100644
--- a/lib/ActiveRecord/UnableToSetFetchMode.php
+++ b/lib/ActiveRecord/UnableToSetFetchMode.php
@@ -25,22 +25,25 @@ class UnableToSetFetchMode extends \RuntimeException implements Exception
 	use AccessorTrait;
 
 	/**
-	 * @var int
+	 * @var mixed
 	 */
 	private $mode;
 
+	/**
+	 * @return mixed
+	 */
 	protected function get_mode()
 	{
 		return $this->mode;
 	}
 
 	/**
-	 * @param int $mode
-	 * @param null $message
+	 * @param mixed $mode
+	 * @param string|null $message
 	 * @param int $code
 	 * @param \Exception|null $previous
 	 */
-	public function __construct($mode, $message = null, $code = 500, \Exception $previous = null)
+	public function __construct($mode, string $message = null, int $code = 500, \Exception $previous = null)
 	{
 		$this->mode = $mode;
 
@@ -50,11 +53,11 @@ public function __construct($mode, $message = null, $code = 500, \Exception $pre
 	/**
 	 * Formats exception message.
 	 *
-	 * @param int $mode
+	 * @param mixed $mode
 	 *
 	 * @return string
 	 */
-	protected function format_message($mode)
+	protected function format_message($mode): string
 	{
 		return format("Unable to set fetch mode: %mode", [ 'mode' => $mode ]);
 	}
diff --git a/lib/ActiveRecord/UpdatedAtProperty.php b/lib/ActiveRecord/UpdatedAtProperty.php
index cd91e9c..9c807dd 100644
--- a/lib/ActiveRecord/UpdatedAtProperty.php
+++ b/lib/ActiveRecord/UpdatedAtProperty.php
@@ -34,7 +34,7 @@ trait UpdatedAtProperty
 	 *
 	 * @return DateTime
 	 */
-	protected function get_updated_at()
+	protected function get_updated_at(): DateTime
 	{
 		return DateTimePropertySupport::get($this->updated_at);
 	}
diff --git a/tests/ActiveRecord/ExceptionTest.php b/tests/ActiveRecord/ExceptionTest.php
index 1183ee2..ee19c04 100644
--- a/tests/ActiveRecord/ExceptionTest.php
+++ b/tests/ActiveRecord/ExceptionTest.php
@@ -25,10 +25,29 @@ public function test_implementing($classname, $ctor_args)
 
 	public function provide_test_implementing()
 	{
-		$fake_model = $this
-			->getMockBuilder(Model::class)
+		$connection = $this
+			->getMockBuilder(Connection::class)
 			->disableOriginalConstructor()
-			->getMockForAbstractClass();
+			->getMock();
+
+		$models = $this
+			->getMockBuilder(ModelCollection::class)
+			->disableOriginalConstructor()
+			->getMock();
+
+		/* @var $models ModelCollection */
+
+		$model = new Model($models, [
+
+			Model::CONNECTION => $connection,
+			Model::NAME => 'testing' . uniqid(),
+			Model::SCHEMA => [
+
+				'id' => 'serial'
+
+			]
+
+		]);
 
 		return [
 
@@ -37,7 +56,7 @@ public function provide_test_implementing()
 			[ 'ConnectionAlreadyEstablished', [ 'connection-name' ] ],
 
 			[ 'RecordNotFound', [ "message", [] ] ],
-			[ 'ScopeNotDefined', [ 'scope-name', $fake_model ] ],
+			[ 'ScopeNotDefined', [ 'scope-name', $model ] ],
 
 			[ 'ModelNotDefined' , [ 'model-name' ] ],
 			[ 'ModelAlreadyInstantiated' , [ 'model-name' ] ],
diff --git a/tests/ActiveRecord/ModelTest.php b/tests/ActiveRecord/ModelTest.php
index 9f144f5..c3014a9 100644
--- a/tests/ActiveRecord/ModelTest.php
+++ b/tests/ActiveRecord/ModelTest.php
@@ -17,7 +17,6 @@
 use ICanBoogie\ActiveRecord\ModelTest\Brand;
 use ICanBoogie\ActiveRecord\ModelTest\Car;
 use ICanBoogie\ActiveRecord\ModelTest\Comment;
-use ICanBoogie\ActiveRecord\ModelTest\Driver;
 use ICanBoogie\DateTime;
 use ICanBoogie\OffsetNotWritable;
 
@@ -561,7 +560,7 @@ public function test_belongs_to()
 
 			'drivers' => [
 
-				Model::ACTIVERECORD_CLASS => Driver::class,
+				Model::ACTIVERECORD_CLASS => ModelTest\Driver::class,
 				Model::SCHEMA => [
 
 					'driver_id' => 'serial',
@@ -612,7 +611,7 @@ public function test_belongs_to()
 		# driver
 
 		$driver = $drivers->new([ 'name' => 'Madonna' ]);
-		$this->assertInstanceOf(Driver::class, $driver);
+		$this->assertInstanceOf(ModelTest\Driver::class, $driver);
 		$driver_id = $driver->save();
 
 		# brand
@@ -625,7 +624,7 @@ public function test_belongs_to()
 		$car->brand_id = $brand_id;
 		$car->save();
 
-		$this->assertInstanceOf(Driver::class, $car->driver);
+		$this->assertInstanceOf(ModelTest\Driver::class, $car->driver);
 		$this->assertInstanceOf(Brand::class, $car->brand);
 
 		$car->driver_id = null;
diff --git a/tests/ActiveRecordTest/Sample.php b/tests/ActiveRecordTest/Sample.php
index b404038..621f038 100644
--- a/tests/ActiveRecordTest/Sample.php
+++ b/tests/ActiveRecordTest/Sample.php
@@ -33,7 +33,7 @@ protected function get_id()
 	 *
 	 * @inheritdoc
 	 */
-	protected function alter_persistent_properties(array $properties, ActiveRecord\Model $model)
+	protected function alter_persistent_properties(array $properties, ActiveRecord\Model $model): array
 	{
 		return array_merge(parent::alter_persistent_properties($properties, $model), [