From: Erik Veenstra <erikveen@...>
Date: 2006-07-11T05:14:55+09:00
Subject: Re: instance_exec

> > I don't understand this though. isn't the memory freed when
> > done? Or is some symbol getting created in the process, or
> > ?

define_method creates a symbol, beneath the surface:

 symbols1 = Symbol.all_symbols
 Module.new.instance_eval{define_method("bar"){}}
 symbols2 = Symbol.all_symbols
 p symbols2-symbols1             # ===> [:bar]

> Yes, that's why InstanceExecHelper must be included in Object
> (and you only have to do that once).

You should include the Module before Object gets frozen. Who
wants to freeze Object, anyway?... ;]

>  Thread.critical = old

AFAIK, we need to be in critical mode when determining the
method name. As soon as we know it, we can (and should...)
return to old_critical. At least before we call the
block/method.

>  module Kernel
>    def instance_exec(*args, &block)

Kernel#instance_exec ? Does that make sense?

About $SAFE: It's possible to do an instance_eval up to level
5, whereas instance_exec fails on level 4. Challenge?... ;]

gegroet,
Erik V. - http://www.erikveen.dds.nl/