Data::Enum - immutable enumeration classes
```perl 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:
perl my $one = Data::Enum->new( qw[ foo bar baz ] ); my $two = Data::Enum->new( qw[ foo bar baz ] );
All class instances are singletons.
```perl 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
```perl use List::Util 1.56 'mesh';
my %handlers = mesh [ $class->values ], [ $class->predicates ]; ```
This was added in v0.2.1.
This method adds support for match::simple.
The overheard of creating a new class instance and resolving methods may actually take more time than comparing simple strings. When using this in production code, you may want to benchmark performance.
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
COPYRIGHT AND LICENSE
This software is Copyright (c) 2021-2022 by Robert Rothenberg.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)