From: Trans <transfire@...>
Date: 2007-06-02T21:34:44+09:00
Subject: Re: nested methods don't really exist?!



On Jun 2, 7:55 am, "Robert Dober" <robert.do...@gmail.com> wrote:
> On 6/2/07, Robert Klemme <shortcut...@googlemail.com> wrote:
>
>
>
> > >> #b is defined only after #a has been invoked at least once.  I cannot
> > >> think of a scenario where you would want this behavior.
>
> > > There are dynamic behavior scenarios such as memoize where it could be
> > > used. But such cases are pretty rare. So I agree. Unless inner defs
> > > are local to their outer def, akin to local variables, they really
> > > aren't very useful --being little more than a shortcut for (class <<
> > > self; self; end).define_method().
>
> > That's exactly what they are not.  If at all they are a shortcut for
> > self.class.define_method(), i.e. methods defined that way a regular
> > instance methods.
>
> > I also think that for memoize and such other mechanisms are far more
> > useful than current Ruby nested methods.  Actually the current state of
> > affairs is a queer mix, because the definition is nested but the scope
> > is not (they are neither restricted to the current instance nor to the
> > current method).
>
> Robert I think they are:
> # vim: sts=2 sw=2 expandtab nu tw=0:
>
> class A
>   def a
>     def b
>       42
>     end
>   end
>
> end
>
> p A.new.methods.grep(/^b$/)
> A.new.b
> []
> nested.rb:13: undefined method `b' for #<A:0xb7e337a0> (NoMethodError)
>
> Did you overlook David's post?
> I get exactly the same behavior than he does on a 1.8.5 Zenwalk
> I have the impression that OP got the victim of a "leftover" in his irb session.
>
> Cheers
> Robert
>
>  Maybe that is the major reason for them not being too
>
> > useful.
>
> > Kind regards
>
> >         robert


Ah, so inner defs won't be allowed after all. Figures, I guess. Why
have useful syntax when you can throw an error? :/

To be honest, I'm not sure I understand Ruby's vision for the future
these days. Why isn't Ruby further embracing the dynamic revolution
it's helped ignite? For example, why aren't we seeing 'def' become a
method, just like 'new' already is?  I guess maybe the innovation is
over and Matz is settling into performance matters only.

T.