# perldoc > Type::Tiny::Enum

## NAME
    [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown) - string enum type constraints

## SYNOPSIS
    Using via [Types::Standard](https://www.chedong.com/phpMan.php/perldoc/Types%3A%3AStandard/markdown):

      package Horse {
        use Moo;
        use [Types::Standard](https://www.chedong.com/phpMan.php/perldoc/Types%3A%3AStandard/markdown) qw( Str Enum );

        has name    => ( is => 'ro', isa => Str );
        has status  => ( is => 'ro', isa => Enum[ 'alive', 'dead' ] );

        sub neigh {
          my ( $self ) = @_;
          return if $self->status eq 'dead';
          ...;
        }
      }

    Using [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)'s export feature:

      package Horse {
        use Moo;
        use [Types::Standard](https://www.chedong.com/phpMan.php/perldoc/Types%3A%3AStandard/markdown) qw( Str );
        use [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown) Status => [ 'alive', 'dead' ];

        has name    => ( is => 'ro', isa => Str );
        has status  => ( is => 'ro', isa => Status, default => STATUS_ALIVE );

        sub neigh {
          my ( $self ) = @_;
          return if $self->status eq STATUS_DEAD;
          ...;
        }
      }

    Using [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)'s object-oriented interface:

      package Horse {
        use Moo;
        use [Types::Standard](https://www.chedong.com/phpMan.php/perldoc/Types%3A%3AStandard/markdown) qw( Str );
        use [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown);

        my $Status = [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)->new(
          name   => 'Status',
          values => [ 'alive', 'dead' ],
        );

        has name    => ( is => 'ro', isa => Str );
        has status  => ( is => 'ro', isa => $Status, default => $Status->[0] );

        sub neigh {
          my ( $self ) = @_;
          return if $self->status eq $Status->[0];
          ...;
        }
      }

## STATUS
    This module is covered by the Type-Tiny stability policy.

## DESCRIPTION
    Enum type constraints.

    This package inherits from [Type::Tiny](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny/markdown); see that for most documentation. Major differences are
    listed below:

### Constructors
    The "new" constructor from [Type::Tiny](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny/markdown) still works, of course. But there is also:

    "new_union( type_constraints => \@enums, %opts )"
        Creates a new enum type constraint which is the union of existing enum type constraints.

    "new_intersection( type_constraints => \@enums, %opts )"
        Creates a new enum type constraint which is the intersection of existing enum type
        constraints.

### Attributes
    "values"
        Arrayref of allowable value strings. Non-string values (e.g. objects with overloading) will
        be stringified in the constructor.

    "constraint"
        Unlike [Type::Tiny](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny/markdown), you *cannot* pass a constraint coderef to the constructor. Instead rely
        on the default.

    "inlined"
        Unlike [Type::Tiny](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny/markdown), you *cannot* pass an inlining coderef to the constructor. Instead rely on
        the default.

    "parent"
        Parent is always [Types::Standard::Str](https://www.chedong.com/phpMan.php/perldoc/Types%3A%3AStandard%3A%3AStr/markdown), and cannot be passed to the constructor.

    "unique_values"
        The list of "values" but sorted and with duplicates removed. This cannot be passed to the
        constructor.

    "coercion"
        If "coercion => 1" is passed to the constructor, the type will have a coercion using the
        "closest_match" method.

### Methods
    "as_regexp"
        Returns the enum as a regexp which strings can be checked against. If you're checking *a
        lot* of strings, then using this regexp might be faster than checking each string against

          my $enum  = [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)->new(...);
          my $check = $enum->compiled_check;
          my $re    = $enum->as_regexp;

          # fast
          my @valid_tokens = grep $enum->check($_), @all_tokens;

          # faster
          my @valid_tokens = grep $check->($_), @all_tokens;

          # fastest
          my @valid_tokens = grep /$re/, @all_tokens;

        You can get a case-insensitive regexp using "$enum->as_regexp('i')".

    "closest_match"
        Returns the closest match in the enum for a string.

          my $enum = [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)->new(
            values => [ qw( foo bar baz quux ) ],
          );

          say $enum->closest_match("FO");   # ==> foo

        It will try to find an exact match first, fall back to a case-insensitive match, if it still
        can't find one, will try to find a head substring match, and finally, if given an integer,
        will use that as an index.

          my $enum = [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown)->new(
            values => [ qw( foo bar baz quux ) ],
          );

          say $enum->closest_match(  0 );  # ==> foo
          say $enum->closest_match(  1 );  # ==> bar
          say $enum->closest_match(  2 );  # ==> baz
          say $enum->closest_match( -1 );  # ==> quux

    "is_word_safe"
        Returns true if none of the values in the enumeration contain a non-word character. Word
        characters include letters, numbers, and underscores, but not most punctuation or
        whitespace.

### Exports
    [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown) can be used as an exporter.

      use [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown) Status => [ 'dead', 'alive' ];

    This will export the following functions into your namespace:

    "Status"
### is_Status
### assert_Status
### to_Status
    "STATUS_DEAD"
    "STATUS_ALIVE"

    Multiple enumerations can be exported at once:

      use [Type::Tiny::Enum](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AEnum/markdown) (
        Status    => [ 'dead', 'alive' ],
        TaxStatus => [ 'paid', 'pending' ],
      );

### Overloading
    *   Arrayrefification calls "values".

## BUGS
    Please report any bugs to <<https://github.com/tobyink/p5-type-tiny/issues>>.

## SEE ALSO
    [Type::Tiny::Manual](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny%3A%3AManual/markdown).

    [Type::Tiny](https://www.chedong.com/phpMan.php/perldoc/Type%3A%3ATiny/markdown).

    [Moose::Meta::TypeConstraint::Enum](https://www.chedong.com/phpMan.php/perldoc/Moose%3A%3AMeta%3A%3ATypeConstraint%3A%3AEnum/markdown).

## AUTHOR
    Toby Inkster <<tobyink@cpan.org>>.

## COPYRIGHT AND LICENCE
    This software is copyright (c) 2013-2014, 2017-2023 by Toby Inkster.

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

## DISCLAIMER OF WARRANTIES
    THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
    PURPOSE.