From: Rick DeNatale <rick.denatale@...>
Date: 2007-03-10T01:19:33+09:00
Subject: Re: how to aliase a module method?

On 3/8/07, Xavier Noria <fxn@hashref.com> wrote:
> On Mar 9, 2007, at 12:10 AM, dseiler@etceteraedutainment.com wrote:
>
> > On Mar 8, 5:34 am, Xavier Noria <f...@hashref.com> wrote:
> >> I am trying to aliase a module method to some local alias (to ease
> >> some template). I've tried a few variations of
> >>
> >>    alias escape_latex MyUtils.escape_latex
> >>
> >> without luck so far. I could mixin the module or write a wrapper, but
> >> I'd like to know how to accomplish that with alias, or that it is not
> >> possible if that's the case.
> >
> > It's possible, sort of.  Try
> >
> > module TheModule
> >   instance_eval "alias escape_latex MyUtils.escape_latex"
> > end
> >
> > I use a similar technique (originally suggested by Minero Aoki,
> > according to my notes) to replace Thread.critical and
> > Thread.critical=.  I've only tested it in 1.8.2 but I don't think
> > anything's broken it since then.
>
> I don't understand that technique (it is not working here). In fact
> what I don't understand is alias.
>
> In irb we can do
>
>    alias foo sprintf
>
> Why can't we say
>
>    alias foo Math.sqrt

Because alias requires that both arguments be names (or symbols), Note
that it's not a method but is directly performed by the ruby
interpreter.

irb(main):001:0> alias foo Math.sqrt
SyntaxError: compile error
(irb):1: parse error, unexpected '.', expecting $
alias foo Math.sqrt
               ^
        from (irb):1

You're not even getting to eval.c, it's failing to parse.

Module#alias_method requires that it's aruments be symbols
cooresponding to the name.

The other problem is that you are trying to make a name in a different
scope than the name you are aliasing.  As far as I can see this isn't
possible.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/