Perl Guru Forums: Perl Programming Help: Beginner: Re: [ChopperCharles] private and protected methods: Edit Log

I changed the way __foo and run handles its arg checking.

Code

 
package foobar;  
use Carp; 
  
sub new {  
  my $class = shift;  
  my $self = {};  
  bless ($self, $class); 
  return $self; 
}    
 
sub __foo { #private  
  my $name = shift; 
  if ( ref($name) ) { 
      my $self = $name; 
      # make it private 
      if ( ref($self) ne __PACKAGE__ ) { 
          confess("Access to private method denied."); 
      } 
      $name = shift; 
  } 
  print "Hello $name.\n"; 
  return 0;  
}  
  
sub run {#public, but can also be called from this package.  
  my $name = shift; 
  if ( ref($name) ) { 
     my $self = $name; 
     $name = shift; 
     return $self->__foo($name); 
  }  
  else { 
    return  __foo($name); 
  } 
}  
  
sub iAmFoobar { #public  
  return run("foobar");  
}  
1;

To inherit, you need to use the parent.
You can do:
use foobar;
use base foobar;
use parent foobar; # newer

Or look into Moose.pm:
extends 'foobar';

Edit: when you "use parent" it does a require on the module and pushes the module onto @ISA. No need to explicitly push @ISA.

Code

package TacoBell; 
 
use parent foobar;            
  
sub new {  
    my $class = shift; 
    my $self = $class->SUPER::new(); 
    #my $self = {}; 
    #bless ($self, $class); 
    return $self;  
}  
  
sub burrito {  
    my $self = shift; 
    return $self->__foo("Charles");   
    # calling the inherited __foo from parent will fail 
}  
 
sub burrito2 { 
    my $self = shift; 
    # use this form if you need the super class's method  
    # to run before your overrides take place 
    my $x = $self->SUPER::__foo("Charles"); 
    # override some stuff 
    return $x; 
} 
 
1;

Tests

Code

perl -MTacoBell -le '$t=TacoBell->new();$t->iAmFoobar' 
Hello foobar. 
 
perl -MTacoBell -le '$t=TacoBell->new();$t->__foo("Chuck")' 
Access to private method denied. at foobar.pm line 17. 
	foobar::__foo('TacoBell=HASH(0x605998)', 'Chuck') called at -e line 1 
 
perl -Mfoobar -le '$t=foobar->new();$t->iAmFoobar' 
Hello foobar. 
 
perl -Mfoobar -le '$t=foobar->new();$t->__foo("Chuck")' 
Hello Chuck. 
 
 
perl -MTacoBell -le '$t=TacoBell->new();$t->burrito()' 
Access to private method denied. at foobar.pm line 15. 
	foobar::__foo('TacoBell=HASH(0x605998)', 'Charles') called at TacoBell.pm line 17 
	TacoBell::burrito('TacoBell=HASH(0x605998)') called at -e line 1 
 
perl -MTacoBell -e '$t=TacoBell->new();$t->burrito2()' 
Access to private method denied. at foobar.pm line 15. 
	foobar::__foo('TacoBell=HASH(0x605a70)', 'Charles') called at TacoBell.pm line 26 
	TacoBell::burrito2('TacoBell=HASH(0x605a70)') called at -e line 1

Hope that helps

(This post was edited by budman on Mar 29, 2012, 10:00 AM)


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