11.7. Starting the Search from a Different Place
A better solution is to tell Perl to search from a different place in the inheritance chain:
{ package Animal;
sub speak {
my $class = shift;
print "a $class goes ", $class->sound, "!\n";
}
}
{ package Mouse;
@ISA = qw(Animal);
sub sound { 'squeak' }
sub speak {
my $class = shift;
$class->Animal::speak(@_);
print "[but you can barely hear it!]\n";
}
}
Ahh. As ugly as this is, it works. Using this syntax, start with Animal to find speak and use all of Animal's inheritance chain if not found immediately. The first parameter is $class (because we're using an arrow again), so the found speak method gets Mouse as its first entry and eventually works its way back to Mouse::sound for the details.
This isn't the best solution, however. We still have to keep the @ISA and the initial search package in sync (changes in one must be considered for changes in the other). Worse, if Mouse had multiple entries in @ISA, we wouldn't necessarily know which one had actually defined speak.
So, is there an even better way?
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