From: MonkeeSage <MonkeeSage@...>
Date: 2007-12-25T07:15:07+09:00
Subject: Re: module_eval differences between 1.8 & 1.9

On Dec 23, 8:40 am, Frederick Cheung <frederick.che...@gmail.com>
wrote:
> Consider the following:
>
> module Foo
> end
>
> def do_stuff_to_foo(&block)
>    Foo.module_eval &block
> end
>
> In ruby 1.8 you can do something like this
>
> do_stuff_to_foo {def greeting; 'hello'; end}
> Foo.instance_methods #=> ['hello']
>
> In ruby 1.9 however, no method is added to Foo, instead the method is
> added to whoever called do_stuff_to_foo:
>
> do_stuff_to_foo {def greeting; 'hello'; end}
> Foo.instance_methods #=> []
> greeting #=> 'hello'
>
> Of course if you do
> Foo.module_eval {def greeting; 'hello'; end}
> then the method is added to Foo on both 1.8 & 1.9
>
> I had a look throughhttp://eigenclass.org/hiki.rb?Changes+in+Ruby+1.9
> but I didn't see anything that seemed relevant.
> Is this intended? Is there a way to write the do_stuff_to_foo method
> in ruby 1.9 ?
>
> Thanks,
>
> Fred

Apparently it only applies to the block version of #module_eval, the
string version seems to still work the same in 1.9.

module Foo; end
def do_stuff_to_foo(str)
  Foo.module_eval str
end
do_stuff_to_foo %{def greeting; 'hello'; end}
p Foo.instance_methods #=> [:greeting]

Not sure why there's a difference in the block version.

Regards,
Jordan