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ElegantElephant - small library of PHP primitives in EO style. Inspired by Cactoos from @yegor256.

EO principles respected here DevOps By

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PHP was designed and created like a procedural language. Then PHP started support OOP paradigm, but it's not really pure OOP. We got classes but we still use them in a procedural way. This library enforces you to write real objects in a real OOP.


Principle Yes/No
No null
No code in constructors ✔️
No getters and setters ✔️
No mutable objects ✔️
No static methods, not even private ones
No instanceof, type casting, or reflection
No public methods without a contract ✔️
No statements in test methods except assertThat ✔️

Getting started:


  • PHP >= 8.0


composer require maxonfjvipon/elegant-elephant


To get flatten array:

// The result will be [0, 1, 2, 2, 3, 3, 4, 5]
(new ArrFlatten(
  [0, [1], [[2, 2], [3, 3]], [4, 5]],
  deep: 2

To merge arrays:

 * If user is admin, result array will contain permissions field
 * [
 *    'name' => ...,
 *    'age' => ...,
 *    'permissions' => [...],
 *    'projects' => [
 *       ['name' => ..., 'created_at' => ...],
 *       [...],
 *       ...
 *    ]
 * ]
(new ArrMerged(
    'name' => $user->name,
    'age' => $user->age,
  new ArrIf(
    ArrOf::func(fn () => [
      'permissions' => [...]
  new ArrObject(
    new ArrMapped(
      fn (Project $project) => [
        'name' => $project->name,
        'created_at' => $project->created_at

To manipulate with a text:

// To lower case
(new TxtLowered(

// To upper case
(new TxtUpper("Hello"))->asString();

// Join texts, if $isAdmin === TRUE the result will be "Hello Admin" else "Hello username, what'up"
(new TxtJoined([
  "Hello ",
  // Conditional text, behaves like first text if condition is TRUE, like second otherwise
  new TxtCond(
    TxtOf::func(fn () => $user->name())
  // Conditional text, behaves like first text if condition is TRUE, like empty string otherwise
  new TxtIf(
    ", what's up"

To get first x from array of x y points:

$points = [['x' => 1, 'y' => 1], ['x' => 2, 'y' => 2], [...], ...];

  new AtKey(
      new FirstOf(
)->asNumber(); // 1

To get length of filtered array:

(new LengthOf(
  new ArrFiltered(
    [1, 2, 3, 4, 5, 6],
    fn (int $num) => $num > 3
))->asNum(); // 3

Complicated example from commercial project with no visible algorithm:

(new AtKey(                                                   // 12. Get element by key "pump" from given array
  ArrOf::any(                                                 // 11. Try to cast given element to array
    new FirstOf(                                              // 10. Get first element of given array
      new ArrCond(                                            // 9.1. If given sorted jockey pumps are not empty - take them
        new Not(
          new IsEmpty(
            $jockeyPumps = new ArrSticky(                     // 8. Cache given sorted jockey pumps
              new ArrSorted(                                  // 7. Sort given mapped jockey pumps by "cost" key
                new ArrMapped(                                // 6. Map given jockey pumps
                  new ArrCond(                                // 5.1. If optimized jockey pumps are not empty - take them
                    new Not(
                      new IsEmpty(
                        $optimized = new ArrSticky(           // 4. Cached optimized jockey pumps
                          new ArrFiltered(                    // 3. Filter cached jockey pumps with optimization
                            $dbPumps = new ArrSticky(         // 2. Cache jockey pumps
                              new ArrPumpsForJockeySelecting( // 1. Take jockey pumps from somewhere
                            $filterPump(threeFifths: true)
                    new ArrFiltered(                           // 5.2. If opmtimized jockey pumps are empty - filter jockey pumps without optimization
                      $filterPump(threeFifths: false)
                  fn (Pump $pump) => [
                    'pump' => $pump,
                    'cost' => $pump->priceByRates($rates),
        [['pump' => null]]                                      // 9.2. or take [['pump' => null]] otherwise

Static methods

Since PHP does not allow you to have more than one constructor in the class, some classes in the library have public static methods that return an instance of the class and replace secondary constructors. Some classes have private primary constructor to prevent user to use them in a wrong way.

For example take a look at the class ArrOf that has private constructor but let you create an instance of Arr object in a several ways via static methods:

use Maxonfjvipon\ElegantElephant\Arr\ArrOf;
use Maxonfjvipon\ElegantElephant\Any\AnyOf;

// From items
ArrOf::items($item1, $item2, $item3)->asArray(); // [$item1, $item2, $item3]

// From array
ArrOf::array([1, 2, 3])->asArray(); // [1, 2, 3]

// From Maxonfjvipon\ElegantElephant\Any
ArrOf::any(AnyOf::arr(["Hello", "Jeff"]))->asArray(); // ["Hello", "Jeff"]

// From callback
ArrOf::func(fn () => ["Hello", "World"])->asArray(); // ["Hello", "World"]

If you write code and see that you can't create an object via new keyword - definitely it's the class with private constructor but public static methods that replace constructors, so try them.

Union arguments

Almost every classes allows you to pass union-typed arguments to the constructor.

For example, class TxtJoined behaves like a joined string and accepts an array or an instance of Arr that both may contains strings, instances of Txt or both of them.

use Maxonfjvipon\ElegantElephant\Txt\TxtJoined;
use Maxonfjvipon\ElegantElephant\Txt\TxtOf;
use Maxonfjvipon\ElegantElephant\Arr\ArrOf;
use Maxonfjvipon\ElegantElephant\Any\AnyOf;

$joined1 = new TxtJoined([
  " ", 

$joined2 = new TxtJoined(
  ArrOf::func(fn () => [
    new TxtJoined(["Hello", " "]),

$joined1->asString() === $joined2->asString(); // "Hello Jeff" === "Hello Jeff" => TRUE

So when you write code you may not care about conversion an argument to the desired type, for example conversion string to Maxonfjvipon\ElegantElephant\Txt. Just pass what you have to the object, it knows how to deal with it.


Something that has value of any (mixed) type. Any interface has only one public method value that must return something of mixed type.

Any objects

Class Description
AnyFork Behaves like first value if condition is TRUE, like second otherwise
AnyCond Alias of AnyFork
AnyOf Allow you to create Any from array, Arr, string, Txt, number, Num or function
AnySticky Any with caching mechanism
AnyWrap Envelope for Any classes
AtKey Get element from array or Arr by key
AtValue Get key from array or Arr by value
EnsureAny Helper trait to cast mixed
FirstOf Get the first element from array, Arr, string or Txt
LastOf Get the last element from array, Arr, string or Txt


See Any unit tests for better undestanding.


Elegant arrays. Arr interface has only one public method asArray() that must return an array.


There is one more interface that you can use in your own classes - IterableArr that extends Arr and \IteratorAggregate.

\IteratorAggregate allows you to apply spread operator ... to your class. If you want to use spread operator with your class without actual calling asArray() method you should make your class implement IterableArr and use HasArrIterator trait. The trait is the default implementation of spreading Arr classes. And now when you use ... with your class trait calls asArray() behind the scene.

And here is the example for better understanding:

use Maxonfjvipon\ElegantElephant\Arr;
use Maxonfjvipon\ElegantElephant\Arr\IterableArr;
use Maxonfjvipon\ElegantElephant\Arr\HasArrIterator;

class MyArr implements Arr { /** code */ }

class MyIterableArr implements IterableArr {
  use HasArrIterator;
  /** code */

$arr = [...(new MyArr())->asArray()];         // good
$arr = [ MyIterableArr()];              // good, no actual calling asArray()
$arr = [...(new MyIterableArr())->asArray()]; // good, but verbose
$arr = [ MyArr()];                      // wrong

All Arr classes in the library can be spead.

Arr classes

Class Description PHP
ArrCast Cast all elements in given array -
ArrCombined Combine two arrays into signe one array_combine
ArrFork Behaves like first array if condition is TRUE, like second otherwise -
ArrCond Alias Of ArrFork -
ArrEmpty Empty array []
ArrExploded Elements of exploded by separator string explode
ArrFiltered Filter elements of given array by given callback array_filter
ArrFlatten Array flatten with given deep -
ArrIf Behaves like given array if condition is TRUE, like empty otherwise -
ArrKeys Get keys of given array array_keys
ArrMapped Map elements of given array by given callback array_map
ArrMerged Merge given arrays array_merge
ArrObject Alias of ArrSingle [key => value]
ArrOf Allows to create Arr from array, Any or function -
ArrPlucked Pluck an array of values from an array -
ArrRange Array of elements in given range range
ArrReversed Reverse given array array_reverse
ArrSingle Array with single key => value element [key => value]
ArrSorted Sort array by given key or callback sort, usort
ArrSplit Alias or ArrExploded explode, split
ArrSticky Array with cache mechanism -
ArrUnique Array with unique elements array_unique
ArrValues Array of just values of given array (ignore keys) array_values
ArrWith Given array + new given element [...] + [$item]
ArrWithout Given array - element by key unset($arr[$key])
ArrWrap Envelope for Arr classes -
CountArr Default implementation of counting Arr if your Arr impelement Countable count($array)
EnsureArr Helper trait for casting array or Arr to array -
HasArrIterator Default implementation of spreading IterableArr ...$array


See Arr unit test for better undestanding.


Elegant boolean. Logic interface has only one method asBool() that must return bool.

Logic classes

Class Description PHP
Conjunction Conjunction, logical AND and, &&
Conj Alias of Conjunction and, &&
ContainsIn Check if something contains in string, Txt, array or Arr -
Disjunction Disjunction, logical OR or, ||
Disj Alias of Disjunction or, ||
EnsureLogic Helper trait to cast bool or Logic to bool -
GreaterOrEqual Check if first given number is greater than or equal to the second one >=
GreaterThan Check if first given number is greater than the second one >
InArray Check if something contains in array or Arr in_array
InText Check if string or Txt contains in other string or Arr strcontains
IsEmpty Check if string, Txt, array or Arr is empty empty()
IsEqual Check if one mixed element is equal to another ===
IsNotEmpty Chekc if string, Txt, array or Arr is not empty !empty()
IsNotEqual Check if one mixed element is not equal to another !==
IsNull Check if given element is null === null
IsNotNull Check if given element is not null !== null
KeyExists Check if key exists in array or Arr array_key_exists
LessOrEqual Check if first given number is less than or equal to the second one <=
LessThan Check if first given number is less than the second one <
LogicCond Alias of LogicFork -
LogicFork Behaves like first given logic if given condition is TRUE, like second otherwise -
LogicOf Allows you to create Logic from bool or function -
LogicSticky Logic with caching mechanism -
LogicWrap Envelope for Logic classes -
Not Logical Not !
PregMatch Check if string or Txt is match to regular expression preg_match


See Logic unit tests for better undestanding.


Elegant numbers. Num interface has only one method asNumber() that must return float or int.

Num classes

Class Description PHP
ArraySum Alias of SumOf array_sum
Divided Division a / b
EnsureNum Helper trait for casting number or Num to float or int -
LengthOf Length of string, Txt, array or Arr strlen, count
MaxOf Max number max
MinOf Min number min
Multiplied Multiplication a * b
NumFork Behaves like first number if condition is TRUE, like second otherwise -
NumCond Alias of NumFork -
NumIf Behaves like given number if condition is TRUE, like 0 otherwise -
NumOf Allows to create Num from float, int, Any or function -
NumSticky Num with caching mechanism -
NumWrap Envelope for Num classes -
Rounded Rounded number round
SumOf Sum of given numbers or Nums array_sum


See Num unit tests for better undestanding.


Elegant strings. Txt interface has only one method asString() that must return string.


There is one more interface that you can use in your own classes - StringableTxt that extends Txt and \Stringable.

\Stringable allows you to cast your class to string via calling __toString() method. So instead of Txt you can use StringableTxt interface and TxtToString helper trait that calls asString() behind the scene.

Here's an example for better undestanding:

use Maxonfjvipon\ElegantElephant\Txt\StringableTxt;
use Maxonfjvipon\ElegantElephant\Txt\TxtToString;
use Maxonfjvipon\ElegantElephant\Txt;

class MyTxt implements Txt { /** code */ }

class MyStringableTxt implements StringableTxt {
  use TxtToString;
  /** code */

$txt = new MyTxt();
$stringableTxt = new MyStringableTxt();

echo $txt->asString();           // good
echo $stringableTxt;             // good, no actual calling asString()
echo $stringableTxt->asString(); // good, but verbose
echo $txt;                       // wrong

All Txt classes in the library implements StringableTxt.

Txt classes

Class Description PHP
EnsureTxt Helper trait for casting string or Txt to string -
TxtBlank Empty text. ""
TxtFork Behaves like first text if condition is TRUE, like second otherwise -
TxtCond Alias of TxtFork -
TxtIf Behaves like given text if condition is TRUE, likey empty otherwise -
TxtImploded Imploded text by separator implode
TxtJoined Joined text join("", [...])
TxtJsonEncoded Object encoded to JSON as json_encoded
TxtLowered Text in a lower case strtolower
TxtLtrimmed Text trimmed from left ltrim
TxtOf Allows to create Txt from string, number, float, int, Any of function. -
TxtPregReplaced Text with replacements by regex preg_replace
TxtReplaced Text with replacements str_replace
TxtRtimmed Text trimmed from right rtrim
TxtSticky Text with caching mechanism -
TxtSubstr Sub-text substr
TxtToString Default implementation converting Txt to string via __toString() -
TxtTrimmed Text trimmed trim
TxtUpper Text in a upper case strtoupper
TxtWrap Envelope for Txt classes -


See Txt unit test for better undestanding.


Fork repository, make changes, send a pull request. To avoid frustration, before sending your pull request please run:

$ ./

And make sure you have no errors.