NAME
MooseX::Deprecated - mark attributes and methods as deprecated
SYNOPSIS
package Goose
{
use Moose;
has feathers => (is => 'ro');
sub honk { say "Honk!" }
with "MooseX::Deprecated" => {
attributes => [ "feathers" ],
methods => [ "honk" ],
};
}DESCRIPTION
MooseX::Deprecated is a parameterizable role that makes it easy to deprecate particular attributes and methods in a class.
In the SYNOPSIS above, before method modifiers will be installed on the feathers accessor and the honk method, issuing a deprecation warning. Additionally, an after modifier will be installed on the class' BUILD method which will issue deprecation warnings for any deprecated attributes passed to the constructor.
The warning text will be something along the lines of: "%s is a deprecated %s"
Warnings are issued in the "deprecated" warnings category, so can be disabled using:
no warnings qw( deprecated );Warnings can be upgraded to fatal errors with:
use warnings FATAL => qw( deprecated );Warnings will only be issued once per call site.
When consuming the role you must pass either a list of attributes, or a list of methods, or both, as parameters to the role. If you forget to do so, you'll get an error message like: "%s with no list of attributes or methods".
CAVEATS
To deprecate an attribute, the attribute must actually exist at the time you consume this role. In particular, this will not work:
package Goose
{
use Moose;
with "MooseX::Deprecated" => {
attributes => [ "feathers" ],
};
has feathers => (is => 'ro');
}Because the "feathers" attribute isn't defined until after the role is consumed. Attempting the above will die with a nasty error message: "Attribute %s does not exist in %s so cannot be deprecated".
If a deprecated attribute handles any methods via delegation, then calling these methods will result in not one, but two warnings. One warning for calling the delegated method; the other warning for calling the accessor (reader) to obtain the object to delegate to. This could theoretically be changed, but I'm comfortable with the existing situation.
Warnings issued by the accessor (reader) during method delegation come from inside your class, and thus the caller cannot disable them or fatalize them.
BUGS
Please report any bugs to http://rt.cpan.org/Dist/Display.html?Queue=MooseX-Deprecated.
Perl 5.8
The behaviour of warnings::warnif changed significantly between Perl 5.8 and 5.10; the location considered to be the effective caller changed from being "like warn" to being "like carp" (the latter being considerably more useful). Therefore under Perl 5.8, doing things like no warnings "deprecated" in your code to control warnings from this role is rather useless, because your code is unlikely to be considered to be the caller.
In the test suite I just skip the complex test that checks for this on Perl prior to 5.10, allowing you to install this module without a hitch on Perl 5.8. However, you are strongly discouraged from using this module with Perl 5.8.
SEE ALSO
Package::DeprecationManager provides a more powerful and complicated set of features. I'm a simple kind of guy, and don't see the need to allow my caller to pick and choose which deprecations they'd like to ignore based on some API version.
Attribute::Deprecated is cute, but only deals with methods, and ironically not (what Moose calls) attributes.
Devel::Deprecation has some pretty nice features, but is more manual than I'd like, and again only deals with methods.
Not to be confused with Moose::Deprecated which can be used to manage warnings issued by Moose itself.
http://en.wikipedia.org/wiki/Self-deprecation.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2013-2014 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.