Hi Monks, I need some help with OO Perl.
Here by_id function in SORT is not working since object type (for $a and $b) is not defined in the first place.
Can I define them ??
In Module SORT.pm the Function by_id has no idea what's 'id' function we are talking about
My assumption is that SORT.pm need to know at compile time that what is 'id' function and where it's coming from when applied to 'sorting variables' $a and $b 
package main;                             
use X;                                    
use SORT;                                 
my $p = new X(10);                           
my$q = new X(20);                           
my $r = new X(15);                           
foreach my $obj (sort by_id ($p,$q,$r)){  
        print $obj->id;                   
}                                         
                                          
                                          
package X;                
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(id);    
                
sub new {                                 
  my $class =shift;                       
  my $self = { _id => shift };            
  bless $self, $class;                    
}                                         
sub id {                                  
  my $self = shift;                       
  return $self->{_id};                    
}                                         
1;                                        
package SORT;                             
use X;                                    
require Exporter;                         
@ISA = qw(Exporter);                      
@EXPORT = qw(by_id);                      
sub by_id {                               
   $a->id <=> $b->id;                     
}                                         
1;

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Above Code when run gives the error
Can't call method "id" without a package or object reference at SORT.pm

How do I make it working???
Thanks,
Artist

In reply to OO and sorting by artist

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