From: "W. Kent Starr" <elderburn@...>
Date: 2001-11-01T06:44:08+09:00
Subject: [ruby-talk:24037] Re: Overiding a method in another module

Mark Hahn wrote:

> 
> I think this won't work with instances of subclasses of original C1.
> 

Ok, what am I missing/
(Lookingover my las post, not only is it likely I am not understanding
your goal, it is definite my spellcheck doesn't catch my typos!)

module M1
	class C1
		def m_1
			p '1'
		end
		def m_2
			p '2'
		end
		class C11
			def m_1
				p '111'
			end
		end	
	end
	class C2<C1
		def m_2
			p '12'
		end
	end
end

module M2
	include M1
	class C1<M1::C1
		def m_1
			p '21'
		end
	end
end

include M2

C1.new.m_1  # =>21
C2.new.m_2  # =>12
class C3<C1
end
C3.new.m_1  # => 21
C3.new.m_2  # => 2

M1::C1.new.m_1 # => 1

class C4<C1::C11 # =>111
end

C4.new.m_1

class C5<C1
	class C1<C11
		def m_1
			p '51'
		end
	end
end

C5::C1.new.m_1 # =>51

Regards,

Kent Starr
elderburn@mindspring.com

> -----Original Message-----
> From: wyzzrd@ruby-lang.org [mailto:wyzzrd@ruby-lang.org]On Behalf Of W.
> Kent Starr
> Sent: Wednesday, October 31, 2001 11:23 AM
> To: ruby-talk ML
> Subject: [ruby-talk:24018] Re: Overiding a method in another module
> 
> Mark Hahn wrote:
> >
> > I implemented the following.  I think it matches your suggestion.  It
> didn't
> > work:
> >
> > module M1
> >   class C1
> >     def m_1
> >       p '1'
> >     end
> >   end
> > end
> > include M1
> >
> > module M2
> >     module M1
> >       class C1
> >         def m_2
> >           p '2'
> >         end
> >       end
> >     end
> > end
> > include M2
> >
> > C1.new.m_2  -> error: method m_2 undefined
> >
> > -----Original Message-----
> > From: jweirich@one.net [mailto:jweirich@one.net]
> > Sent: Wednesday, October 31, 2001 8:26 AM
> > To: ruby-talk ML
> > Subject: [ruby-talk:23982] Re: Overiding a method in another module
> >
> > >>>>> "Mark" == Mark Hahn <mchahn@facelink.com> writes:
> >
> >     Mark> Here is the situation that I am facing (see below).  I want
> >     Mark> to add method m_2 to class C1 and make sure instances of C2
> >     Mark> (any any other subclass of C1) respond to m_2.  I cannot
> >     Mark> subclass C1 to accomplish this because I have no way to
> >     Mark> change C2 to subclass my new subclass.  I cannot change the
> >     Mark> source of M1 because of the license.  Even if there wasn't a
> >     Mark> license issue, isn't reusability all about using other code
> >     Mark> without changing it?
> >
> >     Mark> module M1    << This is other person's module
> >     Mark>   class C1
> >     Mark>     def m_1
> >     Mark>       ...
> >     Mark>     end
> >     Mark>   end
> >     Mark>   class C2 < C1
> >     Mark>     ...
> >     Mark>   end
> >     Mark> end
> >
> > Just do this in your code somewhere ...
> >
> >     module M1
> >       class C1
> >         def m_2
> >           ...
> >         end
> >       end
> >     end
> >
> > Ruby classes are open, so you can add new methods to them without
> > touching the original source.
> >
> > --
> > -- Jim Weirich     jweirich@one.net    http://w3.one.net/~jweirich
> > ---------------------------------------------------------------------
> > "Beware of bugs in the above code; I have only proved it correct,
> > not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)
> 
> IF i have corrected interpreted your goal (a bi IF), the following
> works:
> 
> module M1
>   class C1
>     def m_1
>       p '1'
>     end
>   end
> end
> 
> # do not touch above ^ or license police will kill you!
> 
> module M2
>   include M1
>   class C1<M1::C1    # extend class C1 from mod M1
>     def m_2
>       p '2'
>     end
>   end
> end
> 
> # did not touch M1 so am safe from license police!
> 
> include M2
> 
> C1.new.m_1     # ==> 1
> C1.new.m_2     # ==> 2
> 
> Is this what you want?
> 
> Regards,
> 
> Kent Starr
> elderburn@mindspring.com