saintmike has asked for the wisdom of the Perl Monks concerning the following question:
Let's say that I want to write a Mixin module that adds the method frobnicate() to a given class Foo:
The Mixin.pm implementation would then look something like this:package Foo; use Mixin qw(frobnicate); sub new { bless {}, shift; } package main; my $foo = Foo->new(); $foo->frobnicate();
Now this works ok until I want to add another internal method to the mixin and call it in the same way:package Mixin; use base 'Exporter'; our @EXPORT_OK = qw(frobnicate); sub frobnicate { print "frobnicating!\n"; }
This will cause $foo->frobnicate() to fail, because frobnerize() isn't known to the object:package Mixin; use base 'Exporter'; our @EXPORT_OK = qw(frobnicate); sub frobnicate { my($self) = @_; $self->frobnerize(); } sub frobnerize { my($self) = @_; print "frobnerizing!\n"; } 1;
Can't locate object method "frobnerize" via package "Foo" at Mixin.pm line 9.I could call frobnerize($self, ...) instead, but I'd like to use the object syntax for various reasons. Also, I could add frobnerize() in the class extended by the Mixin, like
(after adding frobnerize to the EXPORTS_OK array) but that would break the encapsulation, as the main program doesn't care about the internal implementation of Foo's frobnicate(). Or, if I could tell Exporter to use both EXPORTS_OK (frobnicate) and EXPORTS (frobnerize), exporting frobnicate() by request and frobnerize() by default, that would somehow work, although Exporter doesn't seem to support it, and it would, again, break the encapsulation. Better ideas, anyone?use Mixin qw(frobnicate frobnerize);
Back to
Seekers of Perl Wisdom