1Type::Tie(3)          User Contributed Perl Documentation         Type::Tie(3)
2
3
4

NAME

6       Type::Tie - tie a variable to a type constraint
7

SYNOPSIS

9       Type::Tie is a response to this sort of problem...
10
11          use strict;
12          use warnings;
13
14          {
15             package Local::Testing;
16             use Moose;
17             has numbers => ( is => "ro", isa => "ArrayRef[Num]" );
18          }
19
20          # Nice list of numbers.
21          my @N = ( 1, 2, 3, 3.14159 );
22
23          # Create an object with a reference to that list.
24          my $object = Local::Testing->new(numbers => \@N);
25
26          # Everything OK so far...
27
28          # Now watch this!
29          push @N, "Monkey!";
30          print $object->dump;
31
32          # Houston, we have a problem!
33
34       Just declare @N like this:
35
36          use Type::Tie;
37          use Types::Standard qw( Num );
38
39          ttie my @N, Num, ( 1, 2, 3, 3.14159 );
40
41       Now any attempt to add a non-numeric value to @N will die.
42

DESCRIPTION

44       This module exports a single function: "ttie". "ttie" ties a variable
45       to a type constraint, ensuring that whatever values stored in the
46       variable will conform to the type constraint. If the type constraint
47       has coercions, these will be used if necessary to ensure values
48       assigned to the variable conform.
49
50          use Type::Tie;
51          use Types::Standard qw( Int Num );
52
53          ttie my $count, Int->plus_coercions(Num, 'int $_'), 0;
54
55          $count++;            # ok
56          $count = 2;          # ok
57          $count = 3.14159;    # ok, coerced to 3
58          $count = "Monkey!";  # dies
59
60       While the examples in documentation (and the test suite) show type
61       constraints from Types::Standard, but any type constraint objects
62       supporting the Type::API interfaces should work. This includes:
63
64       •   Moose::Meta::TypeConstraint / MooseX::Types
65
66       •   Mouse::Meta::TypeConstraint / MouseX::Types
67
68       •   Specio
69
70       •   Type::Tiny
71
72   About Cloning with Storage::dclone (and Clone::clone)
73       Cloning variables with Storage::dclone works, but cloning with
74       Clone::clone is not possible. See Bug #127576 for Type-Tie: Doesn't
75       work with Clone::clone
76       <https://rt.cpan.org/Public/Bug/Display.html?id=127576>
77

BUGS

79       Please report any bugs to
80       <http://rt.cpan.org/Dist/Display.html?Queue=Type-Tie>.
81

SUPPORT

83       IRC: support is available through in the #moops channel on irc.perl.org
84       <http://www.irc.perl.org/channels.html>.
85

SEE ALSO

87       Type::API, Type::Utils, Moose::Manual::Types, MooseX::Lexical::Types.
88

AUTHOR

90       Toby Inkster <tobyink@cpan.org>.
91

93       This software is copyright (c) 2013-2014, 2018-2019 by Toby Inkster.
94
95       This is free software; you can redistribute it and/or modify it under
96       the same terms as the Perl 5 programming language system itself.
97

DISCLAIMER OF WARRANTIES

99       THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
100       WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
101       MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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105perl v5.34.0                      2021-07-27                      Type::Tie(3)
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