From: Trans <transfire@...>
Date: 2007-11-14T12:12:49+09:00
Subject: Re: method_added/define_method infinite loop



On Nov 13, 3:36 pm, "ara.t.howard" <ara.t.how...@gmail.com> wrote:
> On Nov 13, 2007, at 7:24 AM, Trans wrote:
>
>
>
> > What's the best way to avoid the classic method_added/define_method
> > infinite loop?
>
> >   class X
> >     def self.method_added(name)
> >       p name
> >       define_method(name)
> >          # do something else
> >       end
> >     end
>
> >      def foo; end
> >   end
>
> > This will, of course, print "foo" forever.
>
> > As an aside, anyone else think method_added should also receive a
> > block of the method definition? E.g. this would be a "push" (less the
> > infinite loop issue):
>
> >     def self.method_added(name, &block)
> >       define_method(name, &block)
> >     end
>
> > Thanks!
> > T.
>
> cfp:~ > cat a.rb
> class X
>    class << self
>      def ignoring_added_methods
>        ignoring_added_methods = @ignoring_added_methods
>        @ignoring_added_methods = true
>        yield
>      ensure
>        @ignoring_added_methods = ignoring_added_methods
>      end
>
>      def ignoring_added_methods?
>        defined? @ignoring_added_methods and @ignoring_added_methods
>      end
>
>      def method_added name
>        return if ignoring_added_methods?
>        ignoring_added_methods do
>          p name
>          define_method(:bar){}
>        end
>      end
>    end
>
>     def foo
>     end
> end
>
> cfp:~ > ruby a.rb
> :foo

nice. i like the way you did that. thanks ara.

only question i have is about thread safety --could the instance var
pose a potential problem with that?

T.