In general, bless
associates an object with a class.
package MyClass;
my $object = { };
bless $object, "MyClass";
Now when you invoke a method on $object
, Perl know which package to search for the method.
If the second argument is omitted, as in your example, the current package/class is used.
For the sake of clarity, your example might be written as follows:
sub new {
my $class = shift;
my $self = { };
bless $self, $class;
}