1Type::Tiny::Manual::UsiUnsgeWritChoMnotor3i(b3u)ted PerlTyDpoec:u:mTeinntya:t:iMoannual::UsingWithMoo3(3)
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NAME

6       Type::Tiny::Manual::UsingWithMoo3 - alternative use of Type::Tiny with
7       Moo
8

MANUAL

10   Type Registries
11       In all the examples so far, we have imported a collection of type
12       constraints into each class:
13
14         package Horse {
15           use Moo;
16           use Types::Standard qw( Str ArrayRef HashRef Int Any InstanceOf );
17           use Types::Common::Numeric qw( PositiveInt );
18           use Types::Common::String qw( NonEmptyStr );
19
20           has name    => ( is => 'ro', isa => Str );
21           has father  => ( is => 'ro', isa => InstanceOf["Horse"] );
22           ...;
23         }
24
25       This creates a bunch of subs in the Horse namespace, one for each type.
26       We've used namespace::autoclean to clean these up later.
27
28       But it is also possible to avoid pulling all these into the Horse
29       namespace. Instead we'll use a type registry:
30
31         package Horse {
32           use Moo;
33           use Type::Registry qw( t );
34
35           t->add_types('-Standard');
36           t->add_types('-Common::String');
37           t->add_types('-Common::Numeric');
38
39           t->alias_type('InstanceOf["Horse"]' => 'Horsey');
40
41           has name     => ( is => 'ro', isa => t('Str') );
42           has father   => ( is => 'ro', isa => t('Horsey') );
43           has mother   => ( is => 'ro', isa => t('Horsey') );
44           has children => ( is => 'ro', isa => t('ArrayRef[Horsey]') );
45           ...;
46         }
47
48       You don't even need to import the "t()" function. Types::Registry can
49       be used in an entirely object-oriented way.
50
51         package Horse {
52           use Moo;
53           use Type::Registry;
54
55           my $reg = Type::Registry->for_me;
56
57           $reg->add_types('-Standard');
58           $reg->add_types('-Common::String');
59           $reg->add_types('-Common::Numeric');
60
61           $reg->alias_type('InstanceOf["Horse"]' => 'Horsey');
62
63           has name => ( is => 'ro', isa => $reg->lookup('Str') );
64           ...;
65         }
66
67       You could create two registries with entirely different definitions for
68       the same named type.
69
70         my $dracula = Aristocrat->new(name => 'Dracula');
71
72         package AristocracyTracker {
73           use Type::Registry;
74
75           my $reg1 = Type::Registry->new;
76           $reg1->add_types('-Common::Numeric');
77           $reg1->alias_type('PositiveInt' => 'Count');
78
79           my $reg2 = Type::Registry->new;
80           $reg2->add_types('-Standard');
81           $reg2->alias_type('InstanceOf["Aristocrat"]' => 'Count');
82
83           $reg1->lookup("Count")->assert_valid("1");
84           $reg2->lookup("Count")->assert_valid($dracula);
85         }
86
87       Type::Registry uses "AUTOLOAD", so things like this work:
88
89         $reg->ArrayRef->of( $reg->Int );
90
91       Although you can create as many registries as you like, Type::Registry
92       will create a default registry for each package.
93
94         # Create a new empty registry.
95         #
96         my $reg = Type::Registry->new;
97
98         # Get the default registry for my package.
99         # It will be pre-populated with any types we imported using `use`.
100         #
101         my $reg = Type::Registry->for_me;
102
103         # Get the default registry for some other package.
104         #
105         my $reg = Type::Registry->for_class("Horse");
106
107       Type registries are a convenient place to store a bunch of types
108       without polluting your namespace. They are not the same as type
109       libraries though.  Types::Standard, Types::Common::String, and
110       Types::Common::Numeric are type libraries; packages that export types
111       for others to use. We will look at how to make one of those later.
112
113       For now, here's the best way to think of the difference:
114
115       ·   Type registry
116
117           Curate a collection of types for me to use here in this class.
118           This collection is an implementaion detail.
119
120       ·   Type library
121
122           Export a collection of types to be used across multiple classes.
123           This collection is part of your API.
124
125   Importing Functions
126       We've seen how, for instance, Types::Standard exports a sub called
127       "Int" that returns the Int type object.
128
129         use Types::Standard qw( Int );
130
131         my $type = Int;
132         $type->check($value) or die $type->get_message($value);
133
134       Type libraries are also capable of exporting other convenience
135       functions.
136
137       "is_*"
138
139       This is a shortcut for checking a value meets a type constraint:
140
141         use Types::Standard qw( is_Int );
142
143         if ( is_Int($value) ) {
144           ...;
145         }
146
147       Calling "is_Int($value)" will often be marginally faster than calling
148       "Int->check($value)" because it avoids a method call.  (Method calls in
149       Perl end up slower than normal function calls.)
150
151       Using things like "is_ArrayRef" in your code might be preferable to
152       "ref($value) eq "ARRAY"" because it's neater, leads to more consistent
153       type checking, and might even be faster. (Type::Tiny can be pretty
154       fast; it is sometimes able to export these functions as XS subs.)
155
156       "assert_*"
157
158       While "is_Int($value)" returns a boolean, "assert_Int($value)" will
159       throw an error if the value does not meet the constraint, and return
160       the value otherwise. So you can do:
161
162         my $sum = assert_Int($x) + assert_Int($y);
163
164       And you will get the sum of integers $x and $y, and an explosion if
165       either of them is not an integer!
166
167       Assert is useful for quick parameter checks if you are avoiding
168       Type::Params for some strange reason:
169
170         sub add_numbers {
171           my $x = assert_Num(shift);
172           my $y = assert_Num(shift);
173           return $x + $y;
174         }
175
176       "to_*"
177
178       This is a shortcut for coercion:
179
180         my $truthy = to_Bool($value);
181
182       It trusts that the coercion has worked okay. You can combine it with an
183       assertion if you want to make sure.
184
185         my $truthy = assert_Bool(to_Bool($value));
186
187       Shortcuts for exporting functions
188
189       This is a little verbose:
190
191         use Types::Standard qw( Bool is_Bool assert_Bool to_Bool );
192
193       Isn't this a little bit nicer?
194
195         use Types::Standard qw( +Bool );
196
197       The plus sign tells a type library to export not only the type itself,
198       but all of the convenience functions too.
199
200       You can also use:
201
202         use Types::Standard -types;   # export Int, Bool, etc
203         use Types::Standard -is;      # export is_Int, is_Bool, etc
204         use Types::Standard -assert;  # export assert_Int, assert_Bool, etc
205         use Types::Standard -to;      # export to_Bool, etc
206         use Types::Standard -all;     # just export everything!!!
207
208       So if you imagine the functions exported by Types::Standard are like
209       this:
210
211         qw(
212           Str             is_Str          assert_Str
213           Num             is_Num          assert_Num
214           Int             is_Int          assert_Int
215           Bool            is_Bool         assert_Bool     to_Bool
216           ArrayRef        is_ArrayRef     assert_ArrayRef
217         );
218         # ... and more
219
220       Then "+" exports a horizonal group of those, and "-" exports a vertical
221       group.
222
223   Exporting Parameterized Types
224       It's possible to export parameterizable types like ArrayRef, but it is
225       also possible to export parameterized types.
226
227         use Types::Standard qw( ArrayRef Int );
228         use Types::Standard (
229           '+ArrayRef' => { of => Int, -as => 'IntList' },
230         );
231
232         has numbers => (is => 'ro', isa => IntList);
233
234       Using "is_IntList($value)" should be significantly faster than
235       "ArrayRef->of(Int)->check($value)".
236
237       This trick only works for parameterized types that have a single
238       parameter, like ArrayRef, HashRef, InstanceOf, etc.  (Sorry, "Dict" and
239       "Tuple"!)
240
241   Do What I Mean!
242         use Type::Utils qw( dwim_type );
243
244         dwim_type("ArrayRef[Int]")
245
246       "dwim_type" will look up a type constraint from a string and attempt to
247       guess what you meant.
248
249       If it's a type constraint that you seem to have imported with "use",
250       then it should find it. Otherwise, if you're using Moose or Mouse,
251       it'll try asking those. Or if it's in Types::Standard, it'll look
252       there. And if it still has no idea, then it will assume
253       dwim_type("Foo") means dwim_type("InstanceOf['Foo']").
254
255       It just does a big old bunch of guessing.
256

NEXT STEPS

258       You now know pretty much everything there is to know about how to use
259       type libraries.
260
261       Here's your next step:
262
263       ·   Type::Tiny::Manual::Libraries
264
265           Defining your own type libraries, including extending existing
266           libraries, defining new types, adding coercions, defining
267           parameterizable types, and the declarative style.
268

AUTHOR

270       Toby Inkster <tobyink@cpan.org>.
271

273       This software is copyright (c) 2013-2014, 2017-2020 by Toby Inkster.
274
275       This is free software; you can redistribute it and/or modify it under
276       the same terms as the Perl 5 programming language system itself.
277

DISCLAIMER OF WARRANTIES

279       THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
280       WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
281       MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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285perl v5.30.1                      2020-02-1T2ype::Tiny::Manual::UsingWithMoo3(3)
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