From: TRANS <transfire@...>
Date: 2007-07-13T23:10:45+09:00
Subject: Re: Proposal: runtime-modifying Kernel methods should be keywords

On 7/13/07, John Lam <jlam@iunknown.com> wrote:
> > 3. These methods are exactly the ones that complicate optimizing Ruby in
> > all implementations, including Ruby 1.9, Rubinius, JRuby, Ruby.NET, and
> > others. They confound a compiler's efforts to optimize calls by always
> > leaving open questions about the behavior of a method. Will it need
> > access to a heap-allocated scope? Will it save off a binding or the
> > current call frame? No way to know for sure, since they're methods.
>
> +1
>
> We have a design (not implemented yet) to throw on an attempt to alias
> Kernel#eval by default. We would enable aliasing eval with a command
> line switch along the lines of /MakeItRunSlower :) We have a number of
> optimizations for non-local control flow that take advantage of using
> static analysis of a block/proc body. These optimizations simply
> cannot work in cases where eval appears within the block/proc. If
> folks could alias eval then we can't do any of the optimizations at
> all, and that is clearly a bad thing.

I think 'eval' is a clear choice for keyword. But I'm curious, how
does that effect Binding#eval?

As for the others, I don't think the criteria makes sense exactly.
It's not that one would want to re-implement 'local_variables', for
example, but rather just reuse the name for something else. Is that
dangerous? Well, that's Ruby. There are lots of meta-methods that one
would like to think are always there and always operating as one would
expect, but you can't. We've had a number of discussions on ruby-talk
about externalizing such calls in order to avoid overrides. Keywords
are just another attempt at that.

Just a couple of quick points about particular methods:
  - I hope block_given? ultimately goes away!
  - I wish public/private/protected could just be a matter of
    documentation and leave us too, but I realize that's not
    likely, so personally I'd rather do like Java:
      private def x()
      public def x()
      protected def x()
  - What about module_function as keyword? (another one I don't like)
  - You mention 'binding'. However I prefer my alias 'here'.
    How would I alias a keyword?

T.