From: James Edward Gray II <james@...>
Date: 2005-11-20T06:53:19+09:00
Subject: Re: Cond loop vs iterator and scope questions

On Nov 19, 2005, at 3:47 PM, Todd wrote:

> OK, maybe I'm going about it the wrong way.  I specified it wrong in
> the original post anyway.  What I want to do is have the block be able
> to modify the variables in the method that's yielding to it.
>
> Like:
>
> def foo
>   a = 1
>   yield
>   #block does something with a, such that this a is now a new value,
> say add 1
>   a
> end
>
> foo { #some code here }
>
> => 2

Use block parameters for this:

 >> def foo
 >>   a = 1
 >>   a = yield a
 >>   p a
 >> end
=> nil
 >> foo do |var| var + 1 end
2
=> nil

> After looking at your code, I think I can accomplish this more
> elegantly (by inheriting from Array).

It can be tricky, inheriting from Ruby's core classes and thus is  
probably better avoided.  Favor composition over inheritance.

James Edward Gray II