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Postings from November 2017
On Fri, Nov 03, 2017 at 11:35:28AM +0100, demerphq wrote:
> > From perlop:
> >
> > Assignment operators work as in C. That is,
> >
> > $x += 2;
> >
> > is equivalent to
> >
> > $x = $x + 2;
> >
> > although without duplicating any side effects that dereferencing the
> > lvalue might trigger, such as from C<tie()>. Other assignment
> > operators work similarly.
> >
> > So they're not quite the same.
>
> That comment goes back to the
> a0d0e21ea6ea90a22318550944fe6cb09ae10cda, the 5.000 patch.
>
> Personally I read that as documenting what we do, not that it is correct.
I see it as emphasising that $x will only be evaluated once, and that this
is intentional. For example
my $s = "abc";
sub f : lvalue { print "In f()\n"; $s }
f .= "def";
only calls f() once.
> Isn't that non-obviousness a byproduct of the "12" vs "4123" discrepancy?
>
> It seems to me that if this behavior was well defined then both this
> question and the discrepancy would go away.
From my experience of working on multiconcat, I think it would be a very
hard task to form a well-defined list of behaviours for all the
interactions of tie, overload, number of uninit warnings, etc.
--
The Enterprise successfully ferries an alien VIP from one place to another
without serious incident.
-- Things That Never Happen in "Star Trek" #7
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