blank? and present? commit to return singletons [Xavier Noria & Pavel…

… Pravosud]

The contract of blank? and present? was in principle to return Object, as we
generally do, the test suite and description was consistent with that, but some
examples had comments like "# => true".

This cannot be unclear, we either fix the examples, or update the contract.

Since users may be already assuming singletons due to the examples and the fact
that they were returned before 30ba7ee, the safest option seems to be to revise
the contract and the implementation of String#blank?

The motivation for 30ba7ee was to improve the performance of the predicate, the
refactor based on === is on par regarding speed.

With this commit we start documenting return types using YARD conventions. We
plan to document return types gradually.

activesupport/CHANGELOG.md

@@ -1,3 +1,7 @@
*   `blank?` and `present?` commit to return singletons.

    *Xavier Noria*, *Pavel Pravosud*

*   Fixed Float related error in NumberHelper with large precisions.

    before:

activesupport/lib/active_support/core_ext/object/blank.rb

@@ -4,36 +4,42 @@ class Object
  # An object is blank if it's false, empty, or a whitespace string.
  # For example, '', '   ', +nil+, [], and {} are all blank.
  #
  # This simplifies:
  # This simplifies
  #
  #   if address.nil? || address.empty?
  #   address.nil? || address.empty?
  #
  # ...to:
  # to
  #
  #   if address.blank?
  #   address.blank?
  #
  # @return [true, false]
  def blank?
    respond_to?(:empty?) ? empty? : !self
    respond_to?(:empty?) ? !!empty? : !self
  end

  # An object is present if it's not <tt>blank?</tt>.
  # An object is present if it's not blank.
  #
  # @return [true, false]
  def present?
    !blank?
  end

  # Returns object if it's <tt>present?</tt> otherwise returns +nil+.
  # <tt>object.presence</tt> is equivalent to <tt>object.present? ? object : nil</tt>.
  # Returns the receiver if it's present otherwise returns +nil+.
  # <tt>object.presence</tt> is equivalent to
  #
  # This is handy for any representation of objects where blank is the same
  # as not present at all. For example, this simplifies a common check for
  # HTTP POST/query parameters:
  #    object.present? ? object : nil
  #
  # For example, something like
  #
  #   state   = params[:state]   if params[:state].present?
  #   country = params[:country] if params[:country].present?
  #   region  = state || country || 'US'
  #
  # ...becomes:
  # becomes
  #
  #   region = params[:state].presence || params[:country].presence || 'US'
  #
  # @return [Object]
  def presence
    self if present?
  end
@@ -43,6 +49,8 @@ class NilClass
  # +nil+ is blank:
  #
  #   nil.blank? # => true
  #
  # @return [true]
  def blank?
    true
  end
@@ -52,6 +60,8 @@ class FalseClass
  # +false+ is blank:
  #
  #   false.blank? # => true
  #
  # @return [true]
  def blank?
    true
  end
@@ -61,6 +71,8 @@ class TrueClass
  # +true+ is not blank:
  #
  #   true.blank? # => false
  #
  # @return [false]
  def blank?
    false
  end
@@ -71,6 +83,8 @@ class Array
  #
  #   [].blank?      # => true
  #   [1,2,3].blank? # => false
  #
  # @return [true, false]
  alias_method :blank?, :empty?
end

@@ -79,20 +93,28 @@ class Hash
  #
  #   {}.blank?                # => true
  #   { key: 'value' }.blank?  # => false
  #
  # @return [true, false]
  alias_method :blank?, :empty?
end

class String
  BLANK_MATCHER = /\A[[:space:]]*\z/
  BLANK_RE = /\A[[:space:]]*\z/

  # A string is blank if it's empty or contains whitespaces only:
  #
  #   ''.blank?                 # => true
  #   '   '.blank?              # => true
  #   '　'.blank?               # => true
  #   ' something here '.blank? # => false
  #   ''.blank?       # => true
  #   '   '.blank?    # => true
  #   "\t\n\r".blank? # => true
  #   ' blah '.blank? # => false
  #
  # Unicode whitespace is supported:
  #
  #   "\u00a0".blank? # => true
  #
  # @return [true, false]
  def blank?
    self =~ BLANK_MATCHER
    BLANK_RE === self
  end
end

@@ -101,6 +123,8 @@ class Numeric #:nodoc:
  #
  #   1.blank? # => false
  #   0.blank? # => false
  #
  # @return [false]
  def blank?
    false
  end

activesupport/test/core_ext/blank_test.rb

@@ -5,24 +5,28 @@

class BlankTest < ActiveSupport::TestCase
  class EmptyTrue
    def empty?() true; end
    def empty?
      0
    end
  end

  class EmptyFalse
    def empty?() false; end
    def empty?
      nil
    end
  end

  BLANK = [ EmptyTrue.new, nil, false, '', '   ', "  \n\t  \r ", '　', [], {} ]
  BLANK = [ EmptyTrue.new, nil, false, '', '   ', "  \n\t  \r ", '　', "\u00a0", [], {} ]
  NOT   = [ EmptyFalse.new, Object.new, true, 0, 1, 'a', [nil], { nil => 0 } ]

  def test_blank
    BLANK.each { |v| assert v.blank?,  "#{v.inspect} should be blank" }
    NOT.each   { |v| assert !v.blank?, "#{v.inspect} should not be blank" }
    BLANK.each { |v| assert_equal true, v.blank?,  "#{v.inspect} should be blank" }
    NOT.each   { |v| assert_equal false, v.blank?, "#{v.inspect} should not be blank" }
  end

  def test_present
    BLANK.each { |v| assert !v.present?, "#{v.inspect} should not be present" }
    NOT.each   { |v| assert v.present?,  "#{v.inspect} should be present" }
    BLANK.each { |v| assert_equal false, v.present?, "#{v.inspect} should not be present" }
    NOT.each   { |v| assert_equal true, v.present?,  "#{v.inspect} should be present" }
  end

  def test_presence