From: Chris Roos <chrisjroos@...>
Date: 2006-09-16T08:47:26+09:00
Subject: Ruby keywords vs methods

Hi,

I attended Jim Weirich's talk at Rails Conf on Friday.  It was about
thoughtful library design and contained a section on ways to mitigate
risk when re-opening standard libraries.

Rake uses the following pattern when adding to standard library classes...

class BaseClass
  unless instance_methods.include? "foo"
    def foo
      # meth body here
    end
  end
end

It struck me that it might be quite useful to wrap this up and apply
it to all methods defined for [a] given class[es].  Unfortunately, it
appears not to be (completely) possible.  I thought we might be able
to use the method_added hook, but this gets fired after the method
definition.  We need something to fire right before the method
definition.  As def is a keyword and not a method, we can't override
and add to the default behaviour.  Note, that we can, however, do this
with define_method.

So, my actual question is, why are some things keywords and most
things method calls?  I think it's io (language) that doesn't have any
keywords at all (so I guess it must be possible).  In addition, I'm
interested in whether there are there any plans to increase or
decrease the number of keywords in ruby?

Looking forward to some insight,

Chris