From: Robert Feldt <feldt@...>
Date: 2001-10-25T17:50:15+09:00
Subject: [ruby-talk:23274] Re: Ruby macros

On Thu, 25 Oct 2001, Avi Bryant wrote:

> I'm also a big fan of macros, although I tend towards somewhat more
> flexible metaprogramming styles (see
> http://www.cs.ubc.ca/labs/spl/projects/explicit.html for a vague idea of
> what I mean).  However, I've had this discussion with Matz more than once,
> and he is not interested in having macros in Ruby (at least, not in as
> general a way as they're found in lisp and scheme).  This doesn't mean we
> can't add them ourselves - I've considered, for example, building an
> s-expression syntax for ruby to make macros more feasible.  When a few of
> us were talking about this at RubyConf, Dave Thomas proposed a
> construct where the "is" keyword would pass the preceding syntactic
> element to whatever method followed it - ie,
> 
> class A; end is foo
> 
> would more or less trigger:
> 
> foo("class A; end")
> 
> But your idea of macro methods is interesting too - I believe the research
> language Agora does something very close to this.
> 
I'm not very familiar with Lisp's macro system but the idea seems very
powerful (especially given the recent "Bruce Eckel"-thread discussion of
coding standards etc). However, to me it seems as a potential drawback
would be that you're effectively changing the programming language so that
a future maintainer will have to learn your Ruby dialect before
understanding whats happening. Or is this countered by the fact that the
dialect is closer to the problem domain?

> Useful work includes the recent RubyInRuby parser and Robert Feldt's Ruth
> wrapping of the parse nodes in Ruby.  If anyone is seriously interested in
> Ruby metaprogramming (or more specifically, in the terminology of my
> little research group, Explicit Programming in Ruby), let me know, as I
> may have some time in the next few months to put some work into this.
> 
Will it work as a preprocessor or dynamically? ELIDE seems to be a
preprocessor. Looks interesting though, its on the checkout list!

Cheers,

Robert