MooseX::CascadeClearinUser Contributed Perl DocumentMooseX::CascadeClearing(3)NAMEMooseX::CascadeClearing - Cascade clearer actions across attributes
VERSION
Version 0.02
SYNOPSIS
use Moose;
use MooseX::CascadeClearing;
has master => (
is => 'rw',
isa => 'Str',
lazy_build => 1,
is_clear_master => 1,
);
my @opts = (
is => 'ro', isa => 'Str', clear_master => 'master', lazy_build => 1,
);
has sub1 => @opts;
has sub2 => @opts;
has sub3 => @opts;
sub _build_sub1 { shift->master . "1" }
sub _build_sub2 { shift->master . "2" }
sub _build_sub3 { shift->master . "3" }
sub some_sub {
# ...
# clear master, sub[123] in one fell swoop
$self->clear_master;
}
DESCRIPTIONMooseX::CascadeClearing does the necessary metaclass fiddling to allow
an clearing one attribute to be cascaded through to other attributes as
well, calling their clearers.
The intended purpose of this is to assist in situations where the value
of one attribute is derived from the value of another attribute -- say
a situation where the secondary value is expensive to derive and is
thus lazily built. A change to the primary attribute's value would
invalidate the secondary value and as such the secondary should be
cleared. While it could be argued that this is trivial to do manually
for a few attributes, once we consider subclassing and adding in roles
the ability to "auto-clear", as it were, is a valuable trait. (Sorry,
couldn't resist.)
CAVEAT
We don't yet trigger a cascade clear on a master attribute's value
being set through a setter/accessor accessor. This will likely be
available as an option in the not-too-distant-future.
ATTRIBUTE OPTIONS
We install an attribute metaclass trait that provides two additional
atttribute options, as well as wraps the generated clearer method for a
designated "master" attribute. By default, use'ing this module causes
this trait to be installed for all attributes in the package.
is_clear_master => (0|1)
If set to 1, we wrap this attribute's clearer with a sub that looks
for other attributes to clear.
clear_master => Str
Marks this attribute as one that should be cleared when the named
attribute's clearer is called. Note that no checking is done to
ensure that the named master is actually an attribute in the class.
AUTHOR
Chris Weyl, "<cweyl at alumni.drew.edu>"
BUGS
Please report any bugs or feature requests to
"bug-moosex-cascadeclearing at rt.cpan.org", or through the web
interface at
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-CascadeClearing
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-
CascadeClearing>. I will be notified, and then you'llautomatically be
notified of progress on your bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc MooseX::CascadeClearing
You can also look for information at:
· RT: CPAN's request tracker
http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-CascadeClearing
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-CascadeClearing>
· AnnoCPAN: Annotated CPAN documentation
http://annocpan.org/dist/MooseX-CascadeClearing
<http://annocpan.org/dist/MooseX-CascadeClearing>
· CPAN Ratings
http://cpanratings.perl.org/d/MooseX-CascadeClearing
<http://cpanratings.perl.org/d/MooseX-CascadeClearing>
· Search CPAN
http://search.cpan.org/dist/MooseX-CascadeClearing/
<http://search.cpan.org/dist/MooseX-CascadeClearing/>
ACKNOWLEDGEMENTS
MooseX::AlwaysCoerce, for inspiring me to do this in a slightly more
sane fashion than I was previously.
And of course the Moose team, who have made my life significantly
easier (and more fun!) since 0.17 :)
COPYRIGHT & LICENSE
Copyright (c) 2009, Chris Weyl "<cweyl@alumni.drew.edu>".
This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS OR A PARTICULAR PURPOSE.
See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the
Free Software Foundation, Inc.,
59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
perl v5.14.1 2011-04-04 MooseX::CascadeClearing(3)
