From: Brian Candler <B.Candler@...>
Date: 2003-04-29T06:39:30+09:00
Subject: Re: block.call vs. yield

On Mon, Apr 28, 2003 at 07:02:43PM +0900, Yukihiro Matsumoto wrote:
> In message "Re: block.call vs. yield"
>     on 03/04/28, Gavin Sinclair <gsinclair@soyabean.com.au> writes:
> 
> 
> |>    ... do |thing,|
> |> but I never remember to do that.
> |
> |And that's very ugly, IMO.
> 
> I know, but I have to solve them one at a time.  FYI, I proposed
> block parameter <a> that works like function arguments, but many hated
> it because of its ugliness.  Design is a hard thing indeed.

I certainly agree there :-)

I imagine 'yield semantics' were put in the language to solve some problem,
or make it work better in some circumstances; do you have an example of
that?

If I understand rightly, the 'yield semantics' mean that:

    |a|  given 0 arguments  => a = nil
         given 1 argument   => a = arg
         given 2+ arguments => a = [arg1, arg2, ...]

That gives a slightly odd sort of polymorphism - to be useful, the block
must be able to cope with either a single unwrapped object or an array which
wraps multiple objects.

Suppose block parameters worked like function arguments - how would life be
worse? (ignoring backwards compatibility)

Regards,

Brian.