From: Erik Veenstra <erikveen@...>
Date: 2006-07-23T02:42:17+09:00
Subject: Re: *_eval

> > There must be a difference. If I replace
> > aModule.module_eval with aModule.instance_eval in one
> > spcific situation, the results differ, although
> > self.inspect returns the same value...
>
>  Well, when you use keywords (like `def' 'alias') ruby use the
>  "current" class to know where it must define the method.
>
>  With #instance_eval, the current class is the singleton class and ruby
>  will define singleton methods
>
>  With #module_eval, the current is the class (i.e. self) and ruby define
>  instance methods.

I never heard of this "current" before... Interesting... So,
although the contexts look the same (self and object_id), in
reality, they aren't...

POLS? Well, _I_ am surprised!

gegroet,
Erik V. - http://www.erikveen.dds.nl/

----------------------------------------------------------------

 class Foo
   instance_eval <<-END
     p [self, object_id]

     def bar1
     end
   END

   module_eval <<-END
     p [self, object_id]

     def bar2
     end
   END
 end

 p Foo.method_defined?(:bar1)
 p Foo.method_defined?(:bar2)

 p Foo.new.method(:bar1) rescue nil      # No output!
 p Foo.new.method(:bar2) rescue nil

----------------------------------------------------------------

 [Foo, -605293266]
 [Foo, -605293266]
 false
 true
 #<Method: Foo#bar2>

----------------------------------------------------------------