From: David Alan Black <dblack@...>
Date: 2002-01-01T01:41:22+09:00
Subject: [ruby-talk:29867] Re: Proc.class vs yield

Hi --

On Mon, 31 Dec 2001, Michael Lucas-Smith wrote:

> That's a good solution, thanks.
> But I have to say I'm slightly confused as to why everybody seems so
> against having the Ruby language hide the fact that you're either
> dealing with a block or a proc.
> Why must there only be one? Why do you have to use the keyword proc to
> define a new proc from a block?
>
> The common case is to pass a block around, but when you need it to act
> like an object, you have to turn it in to a proc. I'm all for
> optimisation. So why can't Ruby do it for you - if the method takes >1
> parameters and you hand it some blocks, can't it turn them in to procs
> for you? (taking in to account the & logic to accept the yield block as
> a proc)

Hmmm... I wonder whether part of what you're not liking is the fact
that the {} operator is overloaded: it's a block constructor and also
a hash constructor.  So there needs to be a way to deal with things
like:

  some_method( { "hi" }, { "one" => 1 }, { |x| puts x })

not to mention:

  some_method { "hi" }  # block or (malformed) hash argument?

Could the benefits of having a hash constructor reconcile you to
having to jump through a hoop to go from block to Proc? :-)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav