Learning Perl Objects, References amp;amp; Modules [Electronic resources] نسخه متنی

9.3 Accessing the Instance Data

Because you get the instance as the
first parameter, you can now access the instance-specific data. In
this case, let's add a way to get at the name:

{ package Horse;
@ISA = qw(Animal);
sub sound { "neigh" }
sub name {
my $self = shift;
$$self;
}
}

Now you call for the name:

print $tv_horse->name, " says ", $tv_horse->sound, "\n";

Inside Horse::name,
the @_ array contains just
$tv_horse, which the shift
stores into $self. It's
traditional to shift the first parameter into a variable named
$self for instance methods, so stay with that
unless you have strong reasons otherwise. Perl places no significance
on the name $self, however.[5]

[5] If you
come from another OO language background, you might choose
$this or $me for the variable
name, but you'll probably confuse most other Perl
OO-hackers.

Then $self is dereferenced as a scalar reference,
yielding Mr. Ed. The result is:

Mr. Ed says neigh.