This module provides an internal implementation to track descendants which is faster than iterating through ObjectSpace.

Methods
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Class Public methods
clear()

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 20
def clear
  if defined? ActiveSupport::Dependencies
    @@direct_descendants.each do |klass, descendants|
      if ActiveSupport::Dependencies.autoloaded?(klass)
        @@direct_descendants.delete(klass)
      else
        descendants.reject! { |v| ActiveSupport::Dependencies.autoloaded?(v) }
      end
    end
  else
    @@direct_descendants.clear
  end
end
descendants(klass)

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 14
def descendants(klass)
  arr = []
  accumulate_descendants(klass, arr)
  arr
end
direct_descendants(klass)

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 10
def direct_descendants(klass)
  @@direct_descendants[klass] || []
end
store_inherited(klass, descendant)

This is the only method that is not thread safe, but is only ever called during the eager loading phase.

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 36
def store_inherited(klass, descendant)
  (@@direct_descendants[klass] ||= []) << descendant
end
Instance Public methods
descendants()

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 58
def descendants
  DescendantsTracker.descendants(self)
end
direct_descendants()

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 54
def direct_descendants
  DescendantsTracker.direct_descendants(self)
end
inherited(base)

Source: show | on GitHub 

# File activesupport/lib/active_support/descendants_tracker.rb, line 49
def inherited(base)
  DescendantsTracker.store_inherited(self, base)
  super
end