From: Hal Fulton <hal9000@...>
Date: 2006-10-27T09:04:29+09:00
Subject: Re: Pass block instead of here document?

Luc Juggery wrote:
> Hello All,
> 
> Sorry but I do not really understand the way instance_eval is working
> in this sample:
> 
> def tell( obj, &to_do )
> obj.instance_eval( &to_do )
> end
> 
> I'am new to Ruby and Metaprogramming and this method is still obscure to 
> me.
> Can someone help ?
> Thanks a lot,

Look at it this way: The items inside the block are evaluated
in the context of obj, rather than that of the tell method.

For example:

def tell( obj, &to_do )
   p self
   obj.instance_eval( &to_do )
end

If the to_do block were to print self, it would be the
same as obj (and *different* from what was printed before
the instance_eval).


HTH,
Hal