Perl Language Object-oriented Perl Creating Objects
Example
Unlike many other languages, Perl does not have constructors that allocate memory for your objects. Instead, one should write a class method that both create a data structure and populate it with data (you may know it as the Factory Method design pattern).
package Point;
use strict;
sub new {
my ($class, $x, $y) = @_;
my $self = { x => $x, y => $y }; # store object data in a hash
bless $self, $class; # bind the hash to the class
return $self;
}
This method can be used as follows:
my $point = Point->new(1, 2.5);
Whenever the arrow operator -> is used with methods, its left operand is prepended to the given argument list. So, @_ in new will contain values ('Point', 1, 2.5).
There is nothing special in the name new. You can call the factory methods as you prefer.
There is nothing special in hashes. You could do the same in the following way:
package Point;
use strict;
sub new {
my ($class, @coord) = @_;
my $self = \@coord;
bless $self, $class;
return $self;
}
In general, any reference may be an object, even a scalar reference. But most often, hashes are the most convenient way to represent object data.
