descendants_fetcher

This gem provides functionality similar to descendants_tracker but it doesn't store classes in the array. Instead of this it uses ObjectSpace approach to fetch descendant classes dynamically. It also separates descendants and subclasses: first is like ancestors but in opposite direction (deep), second matches strictly by superclass (children). See examples below.

The main cool feature of this implementation is that unlike with DescendantsTracker parent class doesn't store references to descendant class objects when inherited. It means that it can be safely used for dynamically created classes (via Class.new(...)).

The main caveat of this implementation is that it's obviously slower than DescendantsTracker.

Add this line to your application's Gemfile:

gem 'descendants_fetcher'

And then execute:

$ bundle

Or install it yourself as:

$ gem install descendants_fetcher

class X
  extend DescendantsFetcher
end

class X1 < X
end

class X2 < X
end

class Y < X1
end

X.descendants
# => [X, X1, X2, Y]

X.subclasses
# => [X1, X2]

X1.superclass
# => X

X2.superclass
# => X

Class.new(X) # This class object will be safely garbage-collected!

Bug reports and pull requests are welcome on GitHub at https://github.com/marshall-lee/descendants_fetcher.

The gem is available as open source under the terms of the MIT License.