From: Lars Olsson <lasso@...>
Date: 2009-09-22T18:10:17+09:00
Subject: Re: Monkeypatching multiple classes with similar methods

On 22 Sep, 10:56, Ehsanul Hoque <ehsanul...@hotmail.com> wrote:
> Hey. You just have a tiny couple of bugs. Try this instead (untested, but you get the idea):
>
> [Klass1, Klass2, Klass3].each do |klass|
>   klass.module_eval do
>     alias_method :original_meth, :meth
>     def meth(*stuff, &block)
>       puts "#{self.class}.meth has been patched"
>       original_meth(*stuff, &block)
>     end
>   end
> end
>
>
>
>
>
> > Date: Tue, 22 Sep 2009 17:45:06 +0900
> > From: la...@lassoweb.se
> > Subject: Monkeypatching multiple classes with similar methods
> > To: ruby-t...@ruby-lang.org
>
> > Hello!
>
> > I'm trying to monkeypatch a number of related classes that all
> > implements the same method (meth). The methods all take one required
> > argument (stuff) but some of the individual methods may require more
> > arguments (or a block). All I want to do in each call to meth is to
> > print some debug data and then pass the incoming arguments to the
> > original method. This works great as long as I know the exact number
> > of arguments required, but when the number of arguments starts to
> > change my code breaks badly. Is there any way (in ruby 1.8.7) to
> > "copy" the original method signature when defining my own replacement
> > method?
>
> > /lasso
>
> > --- CODE START ---
> > class Klass1
> >   def meth(stuff)
> >     puts "You've sent #{stuff} to #{self.class}.meth"
> >   end
> > end
>
> > class Klass2
> >   def meth(stuff, &block)
> >     block_text = block_given? ? 'with' : 'without'
> >     puts "You've sent #{stuff} to #{self.class}.meth #{block_text} a
> > block"
> >   end
> > end
>
> > class Klass3
> >   def meth(stuff, morestuff)
> >     puts "You've sent #{stuff} to #{self.class}.meth"
> >   end
> > end
>
> > # Broken monkeypatching. Only works on Klass1
> > [Klass1, Klass2, Klass3].each do |klass|
> >   klass.module_eval do
> >     alias_method :original_meth, :meth
> >     def meth(stuff)
> >       puts "#{self.class}.meth has been patched"
> >       original_meth(stuff)
> >     end
> >   end
> > end
>
> > Klass1.new.meth('one')
> > Klass2.new.meth('two') { 'three' } # Block is not passed after
> > monkeypatching
> > Klass2.new.meth('four')
> > Klass3.new.meth('five', 'six') # Raises ArgumentError after
> > monkeypatching
> > --- CODE END ---
>
> _________________________________________________________________
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> - Visa citerad text -

Exactly what I needed (and even simpler than I though). Your solution
works perfectly. Thank you!

/lasso