From: Sean O'Halpin <sean.ohalpin@...>
Date: 2009-04-19T10:10:09+09:00
Subject: Re: Reffering back to caller's binding

On Sat, Apr 18, 2009 at 6:16 PM, Owein Herrmann <oherrmann@gmail.com> wrote:
> Hello Rubyists,
>
> I am trying to define a helper method which displays a ruby expression
> and then displays the results of that expression via puts. Initially I
> did this, which obviously did not work:
>
> def peval( expression )
>  puts expression
>  puts eval( expression )
>  puts ""
> end
>
> of course when I ran it, the scope of the method does not include
> objects in the calling scope... so then I realized it had to do with
> bindings and I defined this:
>
> def peval
>  f,b = yield
>  puts f
>  puts eval(f,b)
>  puts ""
> end
>
> and this works, but, its really ugly:
>
> peval { ["map.inspect", binding()] }
>
> so my question is, is there a way to obtain the caller's binding so that
> I do not have to specify it in the call? Is this in Pickaxe and I spaced
> out on that section? I eally just want to be able to specify the
> expression (in quotes), get it to display, see the results, move on...

Explicitly specify the block parameter and use its #binding method to
get the binding for where the block was defined, i.e.

def peval(&block)
 f,b = block.call
 puts f
 puts eval(f,block.binding)
 puts ""
end

peval { ["var.inspect"] }

OUTPUT:
var.inspect
[1, 2, 3]

Regards,
Sean