From: ara.t.howard@...
Date: 2006-07-10T22:16:46+09:00
Subject: Re: instance_exec

On Mon, 10 Jul 2006 transfire@gmail.com wrote:

>
> Erik Veenstra wrote:
>> Okay, criticizing somebody's work without providing a
>> "solution", isn't nice at all...
>>
>> So, here's my version...
>>
>> gegroet,
>> Erik V. - http://www.erikveen.dds.nl/
>>
>> PS: I'm still curious about the reason for using a module.
>
> I think the idea was to save frm creting a singleton class, but at the
> expense of a module I don't see why either. Anyway, here the version I
> put in Facets. Please evaluate.
>
> module Kernel
>
>  # Like instace_eval but allows parameters to be passed.
>  #
>  # The implementation is thread-safe thanks to the
>  # Thread.current.object_id trick, but it doesn't work with
>  # immediate values (Fixnums and friends), and most
>  # importantly it bombs when given a frozen object.
>
>  def instance_exec(*args, &block)
>    mname =
> "__instance_exec(#{Thread.current.object_id},#{caller.object_id})"
>    Object.class_eval{ define_method(mname, &block) }
>    begin
>      ret = send(mname, *args)
>    ensure
>      Object.class_eval{ undef_method(mname) }
>    end
>    ret
>  end
>
> end

-a
-- 
suffering increases your inner strength.  also, the wishing for suffering
makes the suffering disappear.
- h.h. the 14th dali lama