Definedness of an Object

PerlingTheUK has asked for the wisdom of the Perl Monks concerning the following question:

All,

I have a matcher that looks through a number of objects and returns the first that matches certain criteria or - if none are found - it returns undef.

Now all I need to know is if the resulting variable is defined or not. As I expect the object to be defined, I croak if no object was found.

So far the theory. Here is the code:

my $ls = Obj::LocationSource->new();
my $dep_tip = $ls->match( { location => $dep_name } );
print Dumper( $dep_tip );
if ( ! defined $dep_tip ){
  croak ( "DATA ERROR: Could not find any location for '$dep_name'" );
}

OUTPUT:
$VAR1 = bless( {
                 '_location' => 'Salisbury',
                 '_id' => 259,
                 '_key' => 'SLSBRY'
               }, 'Object::Location' );
DATA ERROR: Could not find any Location for 'Salisbury' at ***.pl line
+ 45
[download]

I do not understand why ! defined $dep_tip seems to evaluate to true.

Cheers,
PerlingTheUK

Considered by PerlingTheUK: Please delte as I found the error in a later line in the code.
Unconsidered by planetscape: keep (and edit) votes prevented reaping

Comment on Definedness of an Object Select or Download Code

Replies are listed 'Best First'.
Re: Definedness of an Object by diotalevi (Canon) on Mar 14, 2006 at 16:29 UTC
Devel::DProf breaks defined() in one case I'm aware of (it causes overload's stringification to call when it shouldn't). Are you using that? ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply]
Re: Definedness of an Object by Roy Johnson (Monsignor) on Mar 14, 2006 at 15:43 UTC
I don't know why you get that result. It doesn't happen when I try this bit that should be equivalent: `use strict; use warnings; my $dep_name = 'Salisbury'; my $dep_tip = bless( { '_location' => $dep_name, '_id' => 259, '_key' => 'SLSBRY' }, 'Object::Location' ); if ( ! defined $dep_tip ){ use Carp; croak ( "DATA ERROR: Could not find any location for '$dep_name'" ); }` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l]


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