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Postings from August 2010
On Mon, Aug 2, 2010 at 2:02 PM, Mark J. Reed <markjreed@gmail.com> wrote:
> On Sun, Aug 1, 2010 at 6:02 PM, Jonathan Worthington <jonathan@jnthn.net> wrote:
>> No, given-when is smart-matching. The RHS of a smart-match decides what
>> happens. If you do True ~~ 1 then that's 1.ACCEPTS(True) which is going to
>> do +True and thus match.
>
> OK, but what about 0 ~~ True? That's what started this thread,
> extricated from the complicating trappings of given/when. Right now,
> (anything ~~ True) is true, and IMHO that's a misfeature; it's at
> least surprising. I'd expect (anything ~~ True) to be synonymous with
> ?(anything): true only if the LHS boolifies to true. By the same
> token, (anything ~~ False) would be synonymous with !?(anything).
Again, sorry for starting a long thread (I seem to do that, and I
swear I'm not trying... just pointing out the surprises I run into as
I try to code).
I want to stress that what you've said above is kind of moot: the spec
says that ~~True gets a parser warning, so we can consider that
deprecated. The only usage we're supporting, here, is a Bool value
stored in a variable or otherwise generated.
I would argue that that's even worse. For example:
my Bool $trash-status = take-out-the-trash();
... some time later ...
my Bool $dishes-status = wash-the-dishes();
if !$dishes-status && $dishes-status ~~ $trash-status {
say "No chores this week!";
}
Of course, that's a bug, but imagine the poor maintenance programmer
that tries to figure out what's going on. I feel for him/her. The only
advantage he/she will have is that this is likely to be so common an
error that they'll quickly learn to look for it first when
smart-matching is involved :-/
--
Aaron Sherman
Email or GTalk: ajs@ajs.com
http://www.ajs.com/~ajs
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