NAME
Task - The successor to Bundle:: for installing sets of modules
SYNOPSIS
### In Makefile.PL
use inc::Module::Install;
name 'Task-Foo';
abstract 'Install the most common Foo modules';
author 'Adam Kennedy <adamk@cpan.org>';
version_from 'lib/Task/Foo.pm';
license 'perl';
# All the things we need for Foo
requires 'perl' => '5.005';
requires 'Carp' => 0;
requires 'File::Basename' => 0;
requires 'Storable' => 0;
requires 'Params::Util' => '0.06';
WriteAll;
### In lib/Task/Foo.pm
package Task::Foo;
use strict;
use vars qw{$VERSION};
BEGIN {
$VERSION = '1.00';
}
1;
DESCRIPTION
The "Bundle::" namespace has long served as the CPAN's "expansion"
mechanism for module installation. A "Bundle::" module contains no code
in itself, but serves as a way to specify an entire collection of
modules/version pairs to be installed.
The Problem with "Bundle::"
Although it has done a reasonably good job, "Bundle::" modules suffer
from some problems.
Firstly, "Bundle::" functionality is fairly magical. The "Bundle::"
magic needs to be specially implemented by the CPAN client, and a
"Bundle::" dist is treated differently to every other type of dist.
It provides only static dependencies. That is, it only provides a
specific set of dependencies, and you cannot change the list depending
on the platform (for example, installing an extra Win32:: module if the
bundle is being installed on Windows).
Finally, it exists only in CPAN. It is not possible to take a "Bundle::"
dist and just install it, because Makefile.PL files are irrelevant for
"Bundle::" dists.
The irony now is that an ordinary module has far more flexible and
powerful dependency capabilities than "Bundle::" distributions. And
because the functionality is hard-coded into the CPAN clients for the
entire "Bundle::" namespace, moving beyond the current situation is
going to mean a change of namespace.
Requirements for a "Bundle::" Successor
The "Task::" namespace (modeled off the Debian packages of the same
name) is used to provide similar functionality to the traditional
"Bundle::" namespace, but without the need to magic and special
client-side support in order to have them work.
A "Task::" module is implemented as a normal .pm module, with only a
version defined. That .pm module itself should NOT load in all the
dependencies.
This implementation as a module allows normal Perl tools to be able to
load the module and check it's version to confirm you have the required
modules, without the need for a CPAN client involved.
Instead of using a magic POD format, the dependency specification is
implemented using the Makefile.PL, as you would for any other module.
This also means that if the Task needs to check for the existence of a
non-Perl application, or some other dependency, it can be done as well.
And you can adapt the dependencies based on the configuration of the
system.
For example, if a module is upgraded to repair a critical bug that
applies only for Windows platform, you can use two alternate versions
based on platform detection code, rather than needing to apply the
highest version in all cases.
This "normal" implementation also means that "Bundle::" modules can be
created privately and no longer need to be stored in CPAN, opening up
the bundling capability to companies and other non-public users.
You should also be able to do things like encode the full dependencies
for you web application as a private "Task::" dist and send this tarball
to the hosting company.
Their admin can then use the dist to install the required modules from
CPAN and you can be far more certain that the required modules have been
installed than in the traditional case.
Implementation
At this time the preferred implementation is done using Module::Install.
Module::Install allows a much more simplified syntax, and bundles the
required "Do What I Mean" functionality in the distribution itself.
This bundling removes many assumptions on what may or may not be
installed on the the destination system, as the installation logic can
be included in the dist and does not have to be first fetched from CPAN.
It also provides you with the additional functionality from the family
of Module::Install extension classes. See the Module::Install page for
more details.
Of course, this is merely a convention. If you wish to write your
Makefile.PL/Build.PL file using another installer, you are free to do
so.
Please note that this Task class provides no functionality in and of
itself, and your "Task::" distributions do not need to inherit from it.
In general, you also should not need to provide any test scripts for
your "Task::" distribution, although you may wish to add tests to
validate the correct installation if you wish (another option not
available in "Bundle::" distributions).
SUPPORT
Bugs (or really, spelling mistakes) should be reported via the CPAN bug
tracker at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Task>
For other issues, contact the author.
AUTHOR
Adam Kennedy <adamk@cpan.org>
COPYRIGHT
Copyright 2005 - 2008 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.