From: John Mair <jrmair@...>
Date: 2010-10-07T15:35:33+09:00
Subject: Re: Why does Module#include exclude the module's metaclass?

@Thomas,

I agree, in fact I wrote a little C extension to bring this 
functionality to modules http://github.com/banister/real_include
Use it like this:

module M
  def self.hello
    puts "hello from class"
  end

  def bye
    puts "bye from instance"
  end
end

class A
  real_include M
end

A.hello #=> "hello from class"
A.new.bye #=> "bye from instance"

I would love to hear from Matz himself why this limitation is built in; 
as most of the explanations i've heard have just been along the lines of 
"that's not how modules work". In my opinion the current behavior does 
violate the principle of least surprise.

@botp

Thanks for the links :) But I don't see how they are on point at all. 
He's talking there about a 'traits' system, he didn't say *anything* 
about traits bringing in singleton methods or not. Sorry but i can't see 
the relevance :( (though maybe i just don't know enough about traits?!)

John

Thomas Sawyer wrote:
> On Oct 6, 7:33�pm, John Mair <jrm...@gmail.com> wrote:
>> end
>> class A
>>
>> implementation difficulty (not insurmountable, but one all the same),
>> but is this the sole reason? Are there any other reasons for this
>> limitation?
> 
> For no good reason other than a purely theoretical misconception
> concerning single vs multiple inheritance --at least that's the only
> reason I have ever been able to derive from my countless inquiries
> I've made into the subject.
> 
> Over the years I have become increasing convinced that the distinction
> between class and module in Ruby is simply an artifice that inhibits
> the language unduly.

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