From: Jean-Hugues ROBERT <jean_hugues_robert@...>
Date: 2004-04-28T13:35:09+09:00
Subject: Re: Semantics of Multiple Values (updated RCR)

At 08:53 28/04/2004 +0900, you wrote:
>Hi,
>
>In message "Re: Semantics of Multiple Values (updated RCR)"
>     on 04/04/28, Kristof Bastiaensen <kristof@vleeuwen.org> writes:
>
>|Isn't * an array to values converter?
>|(like in method(1, *[2, 3, 4]))?
>
>I don't think so, even with your proposal.  If * (splat operator) is
>an array to values converter,
>
>   def func1(a,b)
>     [a,b]
>   end
>   func1(1, *[2, 3, 4])
>
>should give [1,2], unless values work like LIST in Perl.

I tried it. It raises a wrong number of argument error (4 for 2).
However:
def func1(a,b,*rest)
   [a,b]
end
func1(1, *[2, 3, 4])
do give [1,2]

>|> |*  Comparing multiple values
>|> |*  Unify operator
>|>
>|> I have to confess I couldn't understand those two proposals, how they
>|> behave, and how they are useful.
>|
>|The idea of comparing multiple values would be a kind of
>|syntactic sugar.
>|Instead of writing
>|  x == 1 && y == 2
>|you could write
>|  x, y == 1, 2
>|(which looks much clearer in my eyes).
>
>Not for my eyes.  YMMV.

Not obvious to me either. If feel like I would rather write
if [x, y] == [1, 2] then
OTOH, x, y == 1, 2 may help avoid building 2 Array objects and
speed things up (an optimizing compiler could do that too).

>I don't feel right to mix comparison operands x, 1, and y, 2.
>
>                                                         matz.

I agree.
I feel like extending the syntax is worthwhile if the added
benefit is really significant.

Rather than allowing x, y == 1, 2, I would prefer a more
general x, y =~= 1, 2 whose semantic is richer due to the
fact that it may end up assigning either x, y or both if
they don't exist already (or if they were unbound/freed).

Yours,

Jean-Hugues


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