Front page | perl.perl5.porters |
Postings from December 2010
On 2010-12-01 00:24, Abigail wrote:
> On Tue, Nov 30, 2010 at 10:34:36PM +0100, Dr.Ruud wrote:
>> On 2010-11-29 10:22, Dave Mitchell wrote:
>>> On Sun, Nov 28, 2010 at 05:16:28PM -0800, Father Chrysostomos wrote:
>>>> I know this is what constant.pm used to use, but it causes a bug:
>>>
>>> What do you think is the bug? It seems to be behaving the way I expect.
>>>
>>>> $ perl -MO=Deparse -e' BEGIN{my $x = 5; *foo = sub(){$x}; $x=6} print foo'
>>>> sub BEGIN {
>>>> my $x = 5;
>>>> *foo = sub () {
>>>> $x;
>>>> }
>>>> ;
>>>> $x = 6;
>>>> }
>>>> print 5;
>>
>> The compiler should patch the constsub at the '$x = 6' line.
>
> If the compiler can detect that afterwards $x won't change - but you
> need to be able to solve the halting problem to do that in general.
> For instance,
>
> BEGIN {
> my $x = 5;
> *foo = sub () {$x};
> *bar = sub {$x = shift};
> }
>
> the compiler could only patch the constsub if it knows bar() won't
> be called.
And that is not '$x = CONSTANT', so that should then be a compile error.
--
Ruud
Thread Previous
|
Thread Next