From: Mark Slagell <ms@...>
Date: 2000-12-04T02:21:18+09:00
Subject: [ruby-talk:6778] Re: behavior of Proc#arity?

Yukihiro Matsumoto wrote:
> 
> Hi,
> 
> In message "[ruby-talk:6746] Re: behavior of Proc#arity?"
>     on 00/12/03, Mark Slagell <ms@iastate.edu> writes:
> 
> |Note that POLS can't be entirely satisfied here:
> |
> | a,b,c = 1,2,3    # a=1; b=2; c=3
> | a,b   = 1,2,3    # a=1; b=2
> | a     = 1,2,3    # a=1
> |
> |but, proc{|a| a}.call(1,2) returns an array.  Would we want to
> |distinguish a=1,2 from a=[1,2] ?
> 
> What do you suppose the value of `a' after `a=1,2'?
> I think it should be [1,2].  And my copy of miniruby works so now.
> 
>                                                         matz.

This illustrates how a Principle Of No Surprise language would be
impossible, I guess... Yes I have to agree with you that [1,2] makes
more sense, now that I've scratched my beard a little. A single variable
on the left should get everything on the right; two or more on the left
means special array assignment rules can take effect. The only way to be
utterly consistent would be to assign 1 for 'a=1,2' and [1,2] for
'a=[1,2]', but I think lots of people wouldn't like that.  Maybe I
wouldn't like it either in the long run. :-)

  -- Mark