From: Dan Doel <djd15@...>
Date: 2003-11-26T23:57:12+09:00
Subject: Re: Controlled block variables

I actually have wondered in the past why there isn't an #eval that takes 
a proc (other than as a binding).

There's #instance_eval and #module_eval/#class_eval for replacing the 
object scope of a Proc, but
there's no way you can do this:

def foo
    a = 4
    b = 5

    proc { p a; p b }
end

def bar(p)
    a = 7
    b = 8

    eval p
end

bar(foo)

and get 7 and 8 printed.  I realize that Proc objects are closures, but 
since they're also representations
of sections of code, it would be interesting to be able to switch them 
to dynamic scoping for all the
benefits and problems that causes, and using #eval seems like a fairly 
clean way of denoting that.

Of course, I don't know how big a change that would require for Proc and 
the Ruby interpreter. I'm
not familiar with the internals of either.

Regards.

- Dan