From: Sean O'Halpin <sean.ohalpin@...>
Date: 2005-10-20T05:33:37+09:00
Subject: Re: Method annotation and anonymous functions

On 10/19/05, Paul Brannan <pbrannan@atdesk.com> wrote:
> I like this too.  And there's no reason IMO why we can't have both
> anonymous functions and anonymous closures (so def and lambda could have
> the same syntax but lambda would create a closure, while def would not).

I agree. See the thread "Anonymous methods, blocks etc. (Cont.
'default block params')" starting at ruby-talk/160709 for some recent
discussion about this.

>
> Then we could also have named closures as well:
>
>  class Foo
>    a = 42
>    lambda foo(b, c)
>      puts a, b, c
>    end
>  end

That's an interesting idea. It would certainly be orthogonal. However,
you can already do that with define_method:

  class Foo
    a = 42
    define_method(:foo) do |b, c|
      puts a, b, c
    end
  end

  Foo.new.foo(1,2)
  __END__
  42
  1
  2

> The only problem I have with this is that currently lambda is not a
> keyword; it is a method that takes a block and returns a Proc object.
> Creating new keywords, especially out of existing non-keywords, should
> always be done with caution.

Agreed.

> Currently, the following code works fine:
 [snip]
> But I would imagine that if lambda were a keyword this would confuse the
> parser.

Well, I doubt it would break ~much~ code. It would be quite an unusual
thing to define a function named lamdba(), no?

[snip discussion about || vs <> block local syntax]

I think you're on a losing wicket here. It seems that the zeitgeist is
with the semi-colon to introduce block locals.

Regards,

Sean