I'm working through the design patterns book with some Java colleagues,
trying to present Perl equivalents of their Java code - I call it
pattern-oriented Perl ;)
At the moment, we're discussing the Factory method, and I've put together
some sample code here:
http://www.perfascist.com/factory.tar.gz
I've built a test application (factory/test_list.pl), which sets up and
calls some methods on two objects from the base class List (code for the
List class is in factory/List.pm). In this particular example, the test
script calls an object method 'content' which either lists a directory or
lists a file, depending on what type of List object is instantiated.
The List class is nothing but a placeholder for its subclasses. When it's
constructor method (sub new) is called, it creates an instance of one of its
subclasses, the choice of subclass being based on one of the arguments to
the constructor method. Thereafter, all calls to the List object redirect
arguments to the subclass.
Inside the subclasses (List::Directory in factory/List/Directory.pm and
List::File in factory/List/File.pm), the methods are written as if they were
being called directly, thereby ignoring the existence of a base class.
Is this the factory method, or am I deluding myself? Does anyone have any
decent links for design patterns in Perl?
--Nigel Wetters
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