initializer method called from object constructor, overwriting the another object's variables

sree.nivas has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I have written small perl module and one script. In the constructor of the package, I am using one initializer method. The problem, I'm facing is: When, I create two different objects on the package, latest object's initialize methond is overwritting variables of previously created object. I dont have much knowledge on Perl. Unable to determine the cause. Requesting for some help. I am providing the code( of package and script and program output) below. thank you.


#######################################3
package MyPackage;
use Data::Dumper;

sub new {
    my $ip_addr = shift();
    
 my $self = { "DEVICE_IP" =>$ip_addr };
 bless $self, 'MyPackage';
    
 $self->my_init();
 return $self;
}

my $self_ip = undef;
my $partner_ip = undef;

my $WS_1 = undef;
my $WS_2 = undef;
#----------------------
sub my_init{
    my $this = shift;
    ($WS_1, $WS_2 ) = ('10.199.35.11' , '10.199.35.12');
    
    if($this->{DEVICE_IP} eq $WS_1)
        { $partner_ip = $WS_2; }
    else{ $partner_ip = $WS_1; }
    
        $self_ip = $this->{DEVICE_IP};
    return $this;
}

#-----------------
sub my_method{
    my $this = shift;
    
    print "\n Local IP = $self_ip , Partner IP = $partner_ip \n";
    return 1;
}

1;
__END__

###################################3
#My script is as below:

use MyPackage;

my $local_ip= '10.199.35.11';
my $remote_ip = '10.199.35.12' ;

my $objLocal =  MyPackage::new($local_ip); 

my $ret = $objLocal->my_method();

my $objRemote = MyPackage::new($remote_ip); 

my $ret = $objLocal->my_method();
#####################################
[download]

# output observed is:
 
 Local IP = 10.199.35.11 , Partner IP = 10.199.35.12

 Local IP = 10.199.35.12 , Partner IP = 10.199.35.11

 
Because, I am calling the same old object again, I am expecting the ou
+tput to be:
  Local IP = 10.199.35.11 , Partner IP = 10.199.35.12

  Local IP = 10.199.35.11 , Partner IP = 10.199.35.12
[download]

Comment on initializer method called from object constructor, overwriting the another object's variables Select or Download Code

Replies are listed 'Best First'.
Re: initializer method called from object constructor, overwriting the another object's variables by Old_Gray_Bear (Bishop) on Oct 08, 2010 at 16:16 UTC
The variables `$self_ip` and `$partner_ip` are "class variables" (defined in the package, but outside of one of the methods). Consequently they can be seen by all objects instantiated from the package. And as you found out, anything that can be seen by an object can be modified by the object. If you need them to be part of each object, then they have to be defined in the object by adding them in the `new()`method -- `sub new { my $ip_addr = shift(); my $self = { DEVICE_IP => $ip_addr, self_ip => undef, partner_ip => undef, }; bless $self, 'MyPackage'; $self->my_init(); return($self);` [download] ---- I Go Back to Sleep, Now. OGB	[reply] [d/l] [select]
Re: initializer method called from object constructor, overwriting the another object's variables by choroba (Cardinal) on Oct 08, 2010 at 15:42 UTC
If the partner_ip depends on the device_ip, why is it not another attribute of the object? If you have several objects, each can have a different IP, so each needs its own partner.	[reply]