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Postings from November 2017
On 11/04/2017 01:05 PM, Dave Mitchell wrote:
> 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.
To (hopefully minimally) interject here, would it be valuable if we were
able to do it?
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