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Postings from October 2003
# New Ticket Created by "Graciliano M. P."
# Please include the string: [perl #24139]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=24139 >
Why when you access the {SCALAR} key of a symbol entry in the Symbol Table
of a package it always return a scalar reference?! Even if the scalar, or
any symbol (array, hash, glob) with this name is not defined!
For example:
my $name = 'main::test' ;
if (defined *{$name}{SCALAR}) { print "\$$name\n" ;}
if (defined *{$name}{ARRAY}) { print "\@$name\n" ;}
if (defined *{$name}{HASH}) { print "\%$name\n" ;}
This prints:
$main::test
If you set the array and hash before
@test = %test = 1 ;
it prints:
$main::test
@main::test
%main::test
Soo, it always print true for $main::test!!!
The worst thing is that it always return a scalar reference:
my $name = 'main::test' ;
my $ref = *{$name}{SCALAR} ;
print "$ref\n" ;
This prints:
SCALAR(0x1a6f080)
Soo, it always create a new scalar in the memory, even if you just want to
know if the scalar exists in the memory!
This was tested with Perl-5.6.1-Win32, Perl-5.8.1-Win32 (the new release),
Perl-5.6.1-Linux.
We can see that Devel::Symdump uses
if (defined $val && defined *ENTRY{SCALAR}) {
to test if a scalar exists. But if the value of the scalar is undef it's
says that the scalar is not in the table. And since *ENTRY{SCALAR} always
return a scalar ref it's not needed.
I think that the behavior doesn't work like it should, since for {ARRAY} and
{HASH} it works like we want. At least this need to be documented!
Regards,
Graciliano M. P.
You can see this posted at perlmonks.com and see what they say:
http://www.perlmonks.com/index.pl?node_id=297182
Please, fix perlbug for Win32, or add a post form at
http://rt.perl.org/perlbug/!!!
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