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Postings from June 2012
On 26 June 2012 13:06, Lukas Mai <l.mai@web.de> wrote:
> On 2012-06-26 demerphq wrote:
>
>> On 25 June 2012 22:51, Father Chrysostomos via RT
>> <perlbug-followup@perl.org> wrote:
>> > Allowing an empty list provides a clear benefit and makes things
>> > more consistent. What problems could it cause?
>>
>> It would make debugging difficult. Consider generated code, etc.
>
> How would it make debugging more difficult?
Because nonsensical code wont produce a warning or error.
>> I am with Reini on this one, and ill drag in Larry too. Im pretty sure
>> if Larry thought that
>>
>> my ();
>>
>> should be legal it already would be.
>
> See
> http://perl5.git.perl.org/perl.git/blob/09bef84370e90d727656ea11ba5ee8be80e361d3:/perly.y#l661
>
> 655 myattrterm: MY myterm myattrlist
> 656 { $$ = my_attrs($2,$3); }
> 657 | MY myterm
> 658 { $$ = localize($2,$1); }
> 659 ;
> 660
> 661 myterm : '(' expr ')'
> 662 { $$ = sawparens($2); }
> 663 | '(' ')'
> 664 { $$ = sawparens(newNULLLIST()); }
>
> The "myterm : '(' ')'" branch explicitly allows this syntax. It was
> added to perl in 1999. The fact that other passes of the compiler can't
> handle the generated structure is a bug (probably just an oversight,
> since the fix is literally four tokens long).
Well since we are both speculating maybe we should just ask him.
>> That my behaves "a little different" isn't new, we allow the special
>> use of undef in a my() declaration:
>>
>> my ($x,undef,$y)= @l;
>>
>> I contend that allowing my (); would make debugging difficult. I also
>> contend that it is meaningless/absurd to "declare zero items".
>
> To me your argument feels like you'd also want to make m/foo|/
> invalid because it would be meaningless to "match zero characters".
> (And by extension 0 is not an actual number, because it would be
> meaningless to "count zero items".) In other words, I don't find it
> convincing.
>
>> Does C allow you to write:
>>
>> int;
>>
>> ?
>
> No, but it allows 'int ()'. It means something entirely different but
> that's because C is not Perl. (Does C allow you to write 'printf("%d",
> int i++)'?)
And thats a good example, yes perl allows you to write
printf "%d", my $x=10;
but should it really allow:
printf "%d", my(), my(), my(), my(),my $x=10,my();
?
Yves
--
perl -Mre=debug -e "/just|another|perl|hacker/"
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