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Postings from August 2012
Peter Scott <Peter@PSDT.com> writes:
> Every hypothetical case I've seen involving wildly heterogeneous
> 'when' clauses in the same given block has been contrived
> example-ware. I don't see those in real life often enough to justify
> the burden that having ~~ in the language would exact in too many
> other cases.
Indeed.
Case (switch, select, ...) statements have always been intended to serve
two purposes: the programmer and the compiler. To the programmer it
provides a quick and hopefully elegant way to test something against
several constant values. Constant is important for the second purpose,
since it can be compiled into a very efficient branch table.
For its implementation in Perl5 I only see beneficial:
for ( ... ) { # or given
when ( 404 ) { ... }
when ( 501, 503, 777 ) { ... }
... otherwise ...
}
and
for ( ... ) { # or given
when ( "head" ) { ... }
when ( "p", "div", "article" ) { ... }
... otherwise ...
}
It would be very nice if it were possible to use use constant constants
but much to my astonishment these constants do not seem to be
sufficiently constant.
I see no real benefits in adding given/when as mere syntactic sugar
for chained if/then/else constructs. We already have enough of these.
As for using smartmatch, see below.
> I regret to say that I have come to think of it as the
> too-smart-for-its-own-good-match operator.
Precisely.
Smartmatch was a good idea but unfortunately it turns out to be a big
implementation/usage problem. Beyond repair, I'm afraid.
-- Johan
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