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Postings from August 2012
On Fri, Aug 17, 2012 at 03:24:10PM +0200, Abigail wrote:
> On Thu, Aug 16, 2012 at 05:58:16PM -0400, Ricardo Signes wrote:
> >
> > So, last year I said "we really ought to cut most of smart match away."
> >
> > http://www.nntp.perl.org/group/perl.perl5.porters/2011/07/msg174272.html
> >
> > I've slept on it about 380 times, and I'm still for it. Here's the new plan:
> >
> > ## The New ~~ Operator
> >
> > $a $b Meaning
> > ======= ======= ======================
> > Any undef ! defined $a
> > Any ~~-overloaded ~~ overloading is used
> > ~~-ol Any ~~ overloading is used (reversed)
> > Any CodeRef, &{}-ol $b->($a)
> > Any Regexp, qr-ol $a =~ $b
> > Any Simple $a eq $b
> > Any Any fatal
> >
> > This is a nearly a subset of the current behavior. Here are some major points:
> >
> > (1) This is ordered for the sake of knowing which overload to use first.
> >
> > (2) A simple scalar (non-reference, non-glob, non-vstring) on the rhs is
> > used for stringwise equality. I have not yet seen any convincing argument
> > that we can correctly intuit an eq/== behavior, so we pick one.
>
> For me, one of the few advantages I saw in using ~~ is not having to
> wonder when to use == vs eq vs =~. The above table suggests that
>
> "0.0" ~~ 0
>
> is false, while it's currently true. That bothers me.
On the other hand, it makes a lot more sense to me.
> IMO, a "smart match"
> should be able to say, "hmmm, both my operands look like numbers, you know
> what, I'll use '==' to compare them!"
>
> Would this be workable:
>
> $a $b Meaning
> ======= ======= ======================
> Any undef ! defined $a
> Any ~~-overloaded ~~ overloading is used
> ~~-ol Any ~~ overloading is used (reversed)
> Any CodeRef, &{}-ol $b->($a)
> Any Regexp, qr-ol $a =~ $b
> Any Looks like number $a == $b (without a "isn't numeric" warning)
> Any Simple $a eq $b
> Any Any fatal
Honestly, I really can't see myself actually using any version of
smartmatch that actually has a "looks like number" test like that. It's
just too hard to figure out what is actually going to happen to make it
worthwhile for me to actually try to use.
-doy
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