From: itsme213 <itsme213@...>
Date: 2005-01-10T10:26:22+09:00
Subject: Re: List assignment syntax


"Florian Gross" <flgr@ccan.de> wrote in message
news:34a0olF483uq0U2@individual.net...
> Zsban Ambrus wrote:
>
> > I'm a little dissatisfied with the list assignment syntax of ruby.
> > On an example:
> >
> >     irb(main):001:0> a = [2, [3, 5], 8]
> >     => [2, [3, 5], 8]
> >
> > This works:
> >
> >     irb(main):002:0> x, (y, ), z = a
> >     => [2, [3, 5], 8]
>
> Personally, I would like being able to assign to nil in that case. I've
> seen "_" been used as a throw away assignment target, but that's just
> not as expressive as "nil", IMHO.

Is there not a more general pattern-match + assign variables, much like
regular expressions do a pattern-match + assign?

Would it be nice to be able to pick up several pattern-matched variables
concisely for all ruby objects?

list_pattern = list
    # like example above
    # instead of: x = list[0]; y = list[1][0], z = list[2]

hash_pattern = hash
    # instead of: x = hash[:a]; y = hash[:b][:c]; z = hash[:d]

obj_pattern = obj
    # instead of: x = obj.a; y = obj.b.c; z = obj.d

And compose them:
[x, hash_pattern, z] = list_with_item_hash_items

And use them in parameter lists, for loops, etc.
    def f ( event_name, (start, end), response ); .... end
    for x, (y,), z in list_with_item_list_items do ... end

What do other Ruby-ists think?