From: cichol@...
Date: 2015-12-16T15:29:03+00:00
Subject: [ruby-core:72188] [Ruby trunk - Bug #11826] After prepending a module, rewrite Hash#[] takes no effect for calls like Hash.new[:a]

Issue #11826 has been updated by cichol tsai.

Subject changed from In 'prepended', 'class_eval' rewriting a method take no effect to After prepending a module, rewrite Hash#[] takes no effect for calls like Hash.new[:a]
ruby -v set to ruby 2.2.2p95 (2015-04-13 revision 50295) [x64-mingw32]

~~~
module M
end

class Hash
  prepend M
end

class Hash
  def [](k)
    p 3
  end

  def map
    p 4
  end
end

h = {a: 1}
h[:a] #=> return 1 and without print 3
h.send(:[], :a) #=> print 3
h.map # => print 4
~~~

A shorter snippet for the issue.
It seems like an issue only for [] method, maybe something about syntax.
But if use 'include' instead of 'prepend', the 'h[:a]' can give an output.
Please help me check if it is a bug, sorry for bothering.

----------------------------------------
Bug #11826: After prepending a module, rewrite Hash#[] takes no effect for calls like Hash.new[:a]
https://bugs.ruby-lang.org/issues/11826#change-55600

* Author: cichol tsai
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.2.2p95 (2015-04-13 revision 50295) [x64-mingw32]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
~~~
module M
  def self.prepended(clz)
    clz.class_eval do
      def [](k)
        p 1
      end
    end
  end
end

module N
  def self.included(clz)
    clz.class_eval do 
      def []=(k, v)
        p 2
      end
    end
  end
end

class Hash
  prepend M
  include N
end

Hash.new[1]
Hash.new[1]=1
~~~

Running this example gives no output, which is expected to be '1 2'.
I am using 'ruby 2.2.2p95 (2015-04-13 revision 50295) [x64-mingw32]'.
Thanks in advanced.



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