moosex::undeftolerant(3pm) [debian man page]

MooseX::UndefTolerant(3pm)				User Contributed Perl Documentation				MooseX::UndefTolerant(3pm)

NAME

       MooseX::UndefTolerant - Make your attribute(s) tolerant to undef initialization

VERSION

       version 0.17

SYNOPSIS

	 package My::Class;

	 use Moose;
	 use MooseX::UndefTolerant;

	 has 'name' => (
	   is => 'ro',
	   isa => 'Str',
	   predicate => 'has_name'
	 );

	 # Meanwhile, under the city...

	 # Doesn't explode
	 my $class = My::Class->new(name => undef);
	 $class->has_name # False!

       Or, if you only want one attribute to have this behaviour:

	 package My:Class;
	 use Moose;

	 use MooseX::UndefTolerant::Attribute;

	 has 'bar' => (
	     traits => [ qw(MooseX::UndefTolerant::Attribute)],
	     is => 'ro',
	     isa => 'Num',
	     predicate => 'has_bar'
	 );

DESCRIPTION

       Loading this module in your Moose class makes initialization of your attributes tolerant of undef.  If you specify the value of undef to
       any of the attributes they will not be initialized, effectively behaving as if you had not provided a value at all.

       You can also apply the 'UndefTolerant' trait to individual attributes. See MooseX::UndefTolerant::Attribute for details.

       There will be no change in behaviour to any attribute with a type constraint that accepts undef values (for example "Maybe" types), as it
       is presumed that since the type is already "undef tolerant", there is no need to avoid initializing the attribute value with "undef".

       As of Moose 1.9900, this module can also be used in a role, in which case all of that role's attributes will be undef-tolerant.

MOTIVATION

       I often found myself in this quandry:

	 package My:Class;
	 use Moose;

	 has 'foo' => (
	   is => 'ro',
	   isa => 'Str',
	 );

	 # ... then

	 my $foo = ... # get the param from something

	 my $class = My:Class->new(foo => $foo, bar => 123);

       What if foo is undefined?  I didn't want to change my attribute to be Maybe[Str] and I still want my predicate ("has_foo") to work.  The
       only real solution was:

	 if(defined($foo)) {
	   $class = My:Class->new(foo => $foo, bar => 123);
	 } else {
	   $class = My:Class->new(bar => 123);
	 }

       Or some type of codemulch using ternary conditionals.  This module allows you to make your attributes more tolerant of undef so that you
       can keep the first example: have your cake and eat it too!

PER ATTRIBUTE

       See MooseX::UndefTolerant::Attribute.

CAVEATS

       This extension does not currently work in immutable classes when applying the trait to some (but not all) attributes in the class. This is
       because the inlined constructor initialization code currently lives in Moose::Meta::Class, not Moose::Meta::Attribute. The good news is
       that this is expected to be changing shortly.

ACKNOWLEDGEMENTS

       Many thanks to the crew in #moose who talked me through this module:

       Hans Dieter Pearcey (confound)

       Jesse Luehrs (doy)

       Tomas Doran (t0m)

       Dylan Hardison (dylan)

       Jay Shirley (jshirley)

       Mike Eldridge (diz)

AUTHOR

       Cory G Watson <gphat at cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2011 by Cory G Watson.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.14.2							    2012-05-03						MooseX::UndefTolerant(3pm)

Check Out this Related Man Page

MooseX::LazyRequire(3pm)				User Contributed Perl Documentation				  MooseX::LazyRequire(3pm)

NAME

       MooseX::LazyRequire - Required attributes which fail only when trying to use them

SYNOPSIS

	   package Foo;

	   use Moose;
	   use MooseX::LazyRequire;

	   has foo => (
	       is	     => 'ro',
	       lazy_required => 1,
	   );

	   has bar => (
	       is      => 'ro',
	       builder => '_build_bar',
	   );

	   sub _build_bar { shift->foo }

	   Foo->new(foo => 42); # succeeds, foo and bar will be 42
	   Foo->new(bar => 42); # succeeds, bar will be 42
	   Foo->new;		# fails, neither foo nor bare were given

DESCRIPTION

       This module adds a "lazy_required" option to Moose attribute declarations.

       The reader methods for all attributes with that option will throw an exception unless a value for the attributes was provided earlier by a
       constructor parameter or through a writer method.

CAVEATS

       Prior to Moose 1.9900, roles didn't have an attribute metaclass, so this module can't easily apply its magic to attributes defined in
       roles. If you want to use "lazy_required" in role attributes, you'll have to apply the attribute trait yourself:

	   has foo => (
	       traits	     => ['LazyRequire'],
	       is	     => 'ro',
	       lazy_required => 1,
	   );

       With Moose 1.9900, you can use this module in roles just the same way you can in classes.

AUTHORS

       o   Florian Ragwitz <rafl@debian.org>

       o   Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2011 by Florian Ragwitz.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.10.1							    2011-04-04						  MooseX::LazyRequire(3pm)

Linux and UNIX Man Pages

moosex::undeftolerant(3pm) [debian man page]

Check Out this Related Man Page