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Data::Enum - fast, immutable enumeration classes
use Data::Enum; my $color = Data::Enum->new( qw[ red yellow blue green ] ); my $red = $color->new("red"); $red->is_red; # "1" $red->is_yellow; # "" (false) $red->is_blue; # "" (false) $red->is_green; # "" (false) say $red; # outputs "red" $red eq $color->new("red"); # true $red eq "red"; # true
This module will create enumerated constant classes with the following properties:
Any two classes with the same elements are equivalent.
The following two classes are the same:
my $one = Data::Enum->new( qw[ foo bar baz ] ); my $two = Data::Enum->new( qw[ foo bar baz ] );
All class instances are singletons.
my $one = Data::Enum->new( qw[ foo bar baz ] ); my $a = $one->new("foo") my $b = $one->new("foo"); refaddr($a) == refaddr($b); # they are the same thing
Methods for checking values are fast.
$a->is_foo; # constant time $a eq $b; # compares refaddr
Values are immutable (read-only).
This is done by creating a unique internal class name based on the possible values. Each value is actually a subclass of that class, with the appropriate
is_ method returning a constant.
my $class = Data::Enum->new( @values );
This creates a new anonymous class. Values can be instantiated with a constructor:
my $instance = $class->new( $value );
Calling the constructor with an invalid value will throw an exception.
Each instance will have an
is_ method for each value.
Each instance stringifies to its value.
my @values = $class->values;
Returns a list of valid values, stringified and sorted with duplicates removed.
This was added in v0.2.0.
my @predicates = $class->predicates;
Returns a list of predicate methods for each value.
A hash of predicates to values is roughly
use List::Util 1.56 'mesh'; my %handlers = mesh [ $class->values ], [ $class->predicates ];
This was added in v0.2.1.
Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/perl-Data-Enum/issues
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
Robert Rothenberg <email@example.com>
This software is Copyright (c) 2021 by Robert Rothenberg.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)