Re: Confusion over B::PV

PV checks whether the scalar is a string. Use PVX to get the string buffer regardless of whether the scalar is a string. Since PV and PVX can only be called on subclasses of B::PV, you might want to check if you have the right class first.

my $x = $sv->can('PVX') ? $sv->PVX : undef;
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But why are you checking that?! It's equally correct for it to be present and absent.

use strict;
use warnings;

use Test::More tests => 3;

use Devel::Peek;
use B qw( svref_2object SVf_IOK SVf_NOK SVf_POK );

sub is_iv {
   my $sv = svref_2object(my $ref = \$_[0]);
   my $flags = $sv->FLAGS;

   my $pv = $sv->can('PVX') ? $sv->PVX : undef;
  
   if (wantarray) {
       return ($flags & SVf_IOK, $pv);
   } else {
       return $flags & SVf_IOK;
   }
}

my $r = "100";
$r = 100;
Dump($r);

my ($iv, $pv) = is_iv($r);

is($r, 100, "correct value returned SQL_INTEGER");
ok($iv, "ivok bind integer");
ok($pv, "pv not null bind integer");
[download]

Comment on Re: Confusion over B::PV Select or Download Code

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Re^2: Confusion over B::PV by mje (Curate) on May 19, 2012 at 17:14 UTC
Thank you for the explanation. The test is looking to see that the scalar does not look like a string because it wants to behave like a number because it was a number in the database. The test is simply ensuring the scalar was either created with sv_setiv or sql_type_cast_svpv was run on it. Before sql_type_cast_svpv or DBDs like DBD::ODBC (here) set the scalar with sv_setiv the scalar looks like a string then you have to add 0 to all your numbers retrieved from the database before passing them to modules like JSON::XS or they will be turned into "NNN" instead of NNN. Another example was people doing select a_int, b_int from table then performing a_int & b_int which gives the wrong answer unless you add 0 to them first. See http://search.cpan.org/~timb/DBI-1.620/DBI.pm#sql_type_cast and various discussions on dbi-dev mailing list.	[reply]
Re^3: Confusion over B::PV by ikegami (Patriarch) on May 20, 2012 at 03:21 UTC
The test is looking to see that the scalar does not look like a string You want `SvPOK(sv)` which is defined to be `SvFLAGS(sv) & SVf_POK` and is available as `$sv->POK`.	[reply] [d/l] [select]