Ruby » ruby-trunk

The scenario:
* I include Foo in Numeric to provide #bar
* Some other library includes a module in Float to provide #bar
* So I include Foo in Float to use my #bar
* But including Foo in Float is ignored since it's already in the ancestor chain

I think it should be added to the ancestor chain, even if it's already present, since I may want to override some other method earlier in the ancestor chain.

# Including a module already included in a superclass is ignored
>> module Foo; end
=> nil
>> class Numeric; include Foo; end
=> Numeric
>> Float.ancestors
=> [Float, Precision, Numeric, Foo, Comparable, Object, Kernel]
>> class Float; include Foo; end
=> Float
>> Float.ancestors
=> [Float, Precision, Numeric, Foo, Comparable, Object, Kernel]

# Reversing the order of inclusion works as expected
>> module Foo; end
=> nil
>> class Float; include Foo; end
=> Float
>> Float.ancestors
=> [Float, Foo, Precision, Numeric, Comparable, Object, Kernel]
>> class Numeric; include Foo; end
=> Numeric
>> Float.ancestors
=> [Float, Foo, Precision, Numeric, Foo, Comparable, Object, Kernel]

# And so does including a dupe of the existing module in the subclass
>> module Foo; end
=> nil
>> class Numeric; include Foo; end
=> Numeric
>> Float.ancestors
=> [Float, Precision, Numeric, Foo, Comparable, Object, Kernel]
>> class Float; include Foo.dup; end
=> Float
>> Float.ancestors
=> [Float, #<Module:0x19bcd40>, Precision, Numeric, Foo, Comparable, Object, Kernel]