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NAME
Badger - Perl Application Programming Toolkit
SYNOPSIS
use Badger;
# 1) have more fun
# 2) get the job done quicker
# 3) make your code skimpier
# 4) finish work early
# 5) go skateboarding
# 6) enjoy life
DESCRIPTION
The Badger toolkit is a collection of Perl modules designed to simplify
the process of building object-oriented Perl applications. It provides a
set of foundation classes upon which you can quickly build robust and
reliable systems that are simple, skimpy and scalable.
Badger was hewn from the living rock of the Template Toolkit. It
represents all the generic bits of TT that aren't directly related to
template processing. They're also the same kind of generic modules that
have appeared in pretty much every non-trivial Perl application I've
written over the past 10 years or so. So Badger is essentially a
restrospective generalisation of what I've learnt over that time about
the right way (or more accurately, some of the less wrong ways) to build
Perl applications.
Badger is designed to be lightweight, fast, and as simple as it can be
without being too simple. It offers convenience, convention and
consistency in an attempt to improve the Kwalitee of your code and make
it more Skimpy™ (which is my artistic interpretation of what Michael
Schwern refers to as skimmable code - that is, code that is easy to read
and also easy to skim over).
Badger isn't just another object system. Although it does include
functionality to simplify the process of building objects in Perl 5,
that is really just a consequence of the larger goal. That is, to
provide a self-contained set of OO modules that work together in a
harmonious way to implement a basic platform upon which applications
like TT can easily be built.
If you want a comprehensive, highly extensible, postmodern object system
then Moose should almost certainly be at the top of your list. The parts
of Badger that deal with object construction are in some ways similar to
the functionality provided by Moose, not to mention various other object
toolkits available from CPAN. However, Badger only goes as far as doing
what it needs to in terms of object construction in order to get the
rest of the job done. That is, providing a set of objects that do useful
things.
Furthermore, the choice between Badger, Moose, or something else isn't
an either-or decision. There are lots of things that Moose does, that
Badger doesn't, and vice-versa. If you need a really powerful object
system then Moose is probably the way forward. But that doesn't mean you
can't use Badger's file handling tools, codecs, and other useful bits
and pieces alongside your Moose classes. Metaphorically speaking, Badger
and Moose are best friends and they play nicely together. Anyone for
tennis?
CONTENTS
Let's take a quick frolic through the feature list forest to get an idea
what Badger is all about.
Foundation classes for OO programming
Badger includes base classes for creating regular objects
(Badger::Base), mixin objects (Badger::Mixin), prototypes/singletons
(Badger::Prototype), factory classes (Badger::Factory) and central
resource hubs (Badger::Hub).
Class Metaprogramming
The Badger::Class module employs metaprogramming techniques to
simplify the process of defining object classes. It provides methods
to automate many of the annoying trivial tasks required to
"bootstrap" an object class: specifying base classes, version
numbers, exportable symbols, defining constants, loading utility
functions from external modules, creating accessor and mutator
methods, and so on. There are also methods that simplify the process
of accessing class data (e.g. package variables) to save all that
mucking about in symbols tables. Some of these methods will also
account for inheritance between related classes, making it much
easier to share default configuration values between related
classed, for example.
A key feature of Badger::Class is that it does this by a process of
"hygienic class construction". What this means in practice is that
your object classes don't get polluted with methods that are only
used to construct the class (e.g. a method that constructs accessor
methods).
Badger::Class can itself be subclassed, allowing you to build your
own metaprogramming modules tailored to your particular needs.
Error handling and debugging
Base classes and mixin modules provide functionality for both hard
errors in the form of exception-based error handling and soft
errors for declining requests (e.g. to fetch a resource that
doesn't exist) that aren't failures but require special handling.
Methods for debugging (see Badger::Debug) and raising general
warnings are also provided. Generic hooks are provided for receiving
notification of, or implementing custom handling for errors,
warnings and declines. Running alongside this is a generic message
formatting system that allow you to define all error/warning/debug
messages in one place where they can easily be localised (e.g. to a
different spoken language) or customised (e.g. to generate HTML
format instead of plain text).
Symbol Exporter
Badger implements an object oriented version of the Exporter module
in the form of Badger::Exporter. It works correctly with respect to
class inheritance (that is, a subclass automatically inherits the
exportable symbols from its base classes) and provides a number of
additional features to simplify the process of defining exportable
symbols and adding custom import hooks.
Standard utilities and constants.
The Badger::Utils module provides a number of simple utility
functions. It also acts as a delegate to various other standard
utility modules (Scalar::Util, List::Util, List::MoreUtils,
Hash::Util and Digest::MD5). Badger::Constants defines various
constants used by the Badger modules and also of general use. Both
these modules are designed to be subclassed so that you can create
your own collections of utility functions, constants, and so on.
Filesystem modules
The Badger::Filesystem module and friends provide an object-oriented
interface to a filesystem. Files and directories are represented as
Badger::Filesystem::File and Badger::Filesystem::Directory objects
respectively. As well as being useful for general filesystem
manipulation (in this respect, they are very much like the
Path::Class modules), the same modules can also be used to represent
virtual filesystems via the Badger::Filesystem::Virtual module. This
allows you to "mount" a virtual file system under a particular
directory (useful when you're dealing with web sites to map page
URLs, e.g. /example/page.html, to the source files, e.g.
/path/to/example/page.html). You can also create a virtual file
system that is a composite of several root directories (if you're
familiar with the Template Toolkit then think of the way the
"INCLUDE_PATH" works).
Codec modules
Going hand-in-hand with many basic filesystem operations, the codec
modules provide a simple object interface for encoding and decoding
data to and from any particular format. The underlying functionality
is provided by existing Perl modules (e.g. MIME::Base64, Storable,
YAML, etc). The codec modules are wrappers that provide a standard
interface to these various different modules. It provides both
functional and object oriented interfaces, regardless of how the
underlying module works. It also provides the relevant hooks that
allow codec objects to be composed into pipeline sequences.
Free
Badger is Open Source and "free" in both "free beer" and "free
speech" senses of the word. It's 100% pure Perl and has no external
dependencies on any modules that aren't part of the Perl core.
Badger is the base platform for version 3 of the Template Toolkit
(coming RSN) and has portability and ease of installation as primary
goals. Non-core Badger add-on modules can make as much use of CPAN
as they like (something that is usually to be encouraged) but the
Badger core will always be dependency-free to keep it
upload-to-your-ISP friendly.
FURTHER INFORMATION
See the documentation included with the Badger modules, starting with
Badger.pm. Or look online:
http://badgerpower.com/
AUTHOR
Andy Wardley
abw@wardley.org
http://wardley.org/
COPYRIGHT
Copyright (C) 1996-2013 Andy Wardley. All Rights Reserved.
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
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