CODEWITHSUNDEEP
perlfunction
user3385945
user3385945

Reputation: 1275

perl: getting a value from a function of the object

So I have a class AClass with variables (x, y), and a function which should take two objects as arguments of the same class, compute their x and y, and return a new instance of the class with computed values.

package AClass;

sub new {
    my $class = shift;
    my $x = shift;
    my $y = shift;
    my $self  = { 
        x => $x,
        y => $y
    };
    return bless($self, $class);    
}

sub getX {
    my $self = shift;
    return $self->{'x'};
}

sub getY {
    my $self = shift;
    return $self->{'y'};
}

sub addition {
    my ($c1, $c2) = @_;

    return new AClass(
        $c1->getX() + $c1->getX(), 
        $c1->getY() + $c2->getY() 
    );
}


my $a1 = AClass->new(6, 4);
my $a2 = AClass->new(4, 3);

my $val = AClass::addition(\$v1, \$v2);
say $val.getX();

I'm getting error "Can't call method "getX" on unblessed reference". I think the problem is in addition function, when I'm trying to access the values of the objects which are not the real numbers or ?

Upvotes: 0

Views: 130

Answers (2)

Borodin
Borodin

Reputation: 126722

There is a number of problems here.

  • You are using $v1 and $v2 when presumably you mean $a1 and $a2

  • You are passing references to those objects, instead of the objects themselves

  • Your addition method adds the X value of $c1 to itself instead of to the X value of $c2

  • You are using the string concatenation operator . instead of the indirection operator ->

  • It is best to use lower-case letters for lexical identifiers. Capitals are generally reserved for globals like package names

You must always use strict and use warnings at the top of your program. In this case you would have been alerted to the fact that $v1 and $v2 hadn't been declared.

This version of your code works fine

use strict;
use warnings;

package AClass;

sub new {
  my $class = shift;
  my ($x, $y) = @_;
  bless { x => $x, y => $y }, $class;
}

sub get_x {
  my $self = shift;
  $self->{x};
}

sub get_y {
  my $self = shift;
  $self->{y};
}

sub addition {
  my ($c1, $c2) = @_;
  AClass->new(
      $c1->get_x + $c2->get_x,
      $c1->get_y + $c2->get_y
  );
}

package main;

use feature 'say';

my $a1 = AClass->new(6, 4);
my $a2 = AClass->new(4, 3);

my $val = AClass::addition($a1, $a2);
say $val->get_x;

output

10

Upvotes: 5

ikegami
ikegami

Reputation: 385546

You use $v1 instead $a1. Always use use strict; use warnings;.

Also, you're taking a reference for no reason.

my $val = AClass::addition($a1, $a2);

The following would also work (though add) would be a better word:

my $val = $a1->addition($a2);

Upvotes: 3

Related Questions