/usr/share/doc/libmoosex-undeftolerant-perl/README is in libmoosex-undeftolerant-perl 0.19-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 | NAME
MooseX::UndefTolerant - Make your attribute(s) tolerant to undef
initialization
VERSION
version 0.19
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.
|