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Postings from December 2010
On Wed, Dec 01, 2010 at 07:38:30PM +0100, Dr.Ruud wrote:
> 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.
You're proposing a sub of the form 'sub {$x = shift;}' should be
a compile error?
Abigail
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