1 package Moose::Cookbook::Basics::Recipe4;
3 # ABSTRACT: Subtypes, and modeling a simple B<Company> class hierarchy
14 'Regexp::Common' => '0',
23 use Moose::Util::TypeConstraints;
26 use Regexp::Common 'zip';
28 my $STATES = Locale::US->new;
32 ( exists $STATES->{code2state}{ uc($_) }
33 || exists $STATES->{state2code}{ uc($_) } );
39 /^$RE{zip}{US}{-extended => 'allow'}$/;
42 has 'street' => ( is => 'rw', isa => 'Str' );
43 has 'city' => ( is => 'rw', isa => 'Str' );
44 has 'state' => ( is => 'rw', isa => 'USState' );
45 has 'zip_code' => ( is => 'rw', isa => 'USZipCode' );
49 use Moose::Util::TypeConstraints;
51 has 'name' => ( is => 'rw', isa => 'Str', required => 1 );
52 has 'address' => ( is => 'rw', isa => 'Address' );
53 has 'employees' => ( is => 'rw', isa => 'ArrayRef[Employee]' );
56 my ( $self, $params ) = @_;
57 foreach my $employee ( @{ $self->employees || [] } ) {
58 $employee->employer($self);
62 after 'employees' => sub {
63 my ( $self, $employees ) = @_;
64 foreach my $employee ( @{ $employees || [] } ) {
65 $employee->employer($self);
72 has 'first_name' => ( is => 'rw', isa => 'Str', required => 1 );
73 has 'last_name' => ( is => 'rw', isa => 'Str', required => 1 );
74 has 'middle_initial' => (
75 is => 'rw', isa => 'Str',
76 predicate => 'has_middle_initial'
78 has 'address' => ( is => 'rw', isa => 'Address' );
82 return $self->first_name
84 $self->has_middle_initial
85 ? ' ' . $self->middle_initial . '. '
95 has 'title' => ( is => 'rw', isa => 'Str', required => 1 );
96 has 'employer' => ( is => 'rw', isa => 'Company', weak_ref => 1 );
98 override 'full_name' => sub {
100 super() . ', ' . $self->title;
105 This recipe introduces the C<subtype> sugar function from
106 L<Moose::Util::TypeConstraints>. The C<subtype> function lets you
107 declaratively create type constraints without building an entire
110 In the recipe we also make use of L<Locale::US> and L<Regexp::Common>
111 to build constraints, showing how constraints can make use of existing
112 CPAN tools for data validation.
114 Finally, we introduce the C<required> attribute option.
116 In the C<Address> class we define two subtypes. The first uses the
117 L<Locale::US> module to check the validity of a state. It accepts
118 either a state abbreviation of full name.
120 A state will be passed in as a string, so we make our C<USState> type
121 a subtype of Moose's builtin C<Str> type. This is done using the C<as>
122 sugar. The actual constraint is defined using C<where>. This function
123 accepts a single subroutine reference. That subroutine will be called
124 with the value to be checked in C<$_> (1). It is expected to return a
125 true or false value indicating whether the value is valid for the
128 We can now use the C<USState> type just like Moose's builtin types:
130 has 'state' => ( is => 'rw', isa => 'USState' );
132 When the C<state> attribute is set, the value is checked against the
133 C<USState> constraint. If the value is not valid, an exception will be
136 The next C<subtype>, C<USZipCode>, uses
137 L<Regexp::Common>. L<Regexp::Common> includes a regex for validating
138 US zip codes. We use this constraint for the C<zip_code> attribute.
143 /^$RE{zip}{US}{-extended => 'allow'}$/;
146 Using a subtype instead of requiring a class for each type greatly
147 simplifies the code. We don't really need a class for these types, as
148 they're just strings, but we do want to ensure that they're valid.
150 The type constraints we created are reusable. Type constraints are
151 stored by name in a global registry, which means that we can refer to
152 them in other classes. Because the registry is global, we do recommend
153 that you use some sort of namespacing in real applications,
154 like C<MyApp::Type::USState> (just as you would do with class names).
156 These two subtypes allow us to define a simple C<Address> class.
158 Then we define our C<Company> class, which has an address. As we saw
159 in earlier recipes, Moose automatically creates a type constraint for
160 each our classes, so we can use that for the C<Company> class's
161 C<address> attribute:
163 has 'address' => ( is => 'rw', isa => 'Address' );
165 A company also needs a name:
167 has 'name' => ( is => 'rw', isa => 'Str', required => 1 );
169 This introduces a new attribute option, C<required>. If an attribute
170 is required, then it must be passed to the class's constructor, or an
171 exception will be thrown. It's important to understand that a
172 C<required> attribute can still be false or C<undef>, if its type
173 constraint allows that.
175 The next attribute, C<employees>, uses a I<parameterized> type
178 has 'employees' => ( is => 'rw', isa => 'ArrayRef[Employee]' );
180 This constraint says that C<employees> must be an array reference
181 where each element of the array is an C<Employee> object. It's worth
182 noting that an I<empty> array reference also satisfies this
185 Parameterizable type constraints (or "container types"), such as
186 C<ArrayRef[`a]>, can be made more specific with a type parameter. In
187 fact, we can arbitrarily nest these types, producing something like
188 C<HashRef[ArrayRef[Int]]>. However, you can also just use the type by
189 itself, so C<ArrayRef> is legal. (2)
191 If you jump down to the definition of the C<Employee> class, you will
192 see that it has an C<employer> attribute.
194 When we set the C<employees> for a C<Company> we want to make sure
195 that each of these employee objects refers back to the right
196 C<Company> in its C<employer> attribute.
198 To do that, we need to hook into object construction. Moose lets us do
199 this by writing a C<BUILD> method in our class. When your class
200 defines a C<BUILD> method, it will be called immediately after
201 object construction, but before the object is returned to the caller
202 (3). Note that all C<BUILD> methods in your class hierarchy will be
203 called automatically; there is no need to (and you should not) call
204 the superclass C<BUILD> method.
206 The C<Company> class uses the C<BUILD> method to ensure that each
207 employee of a company has the proper C<Company> object in its
208 C<employer> attribute:
211 my ( $self, $params ) = @_;
212 foreach my $employee ( @{ $self->employees || [] } ) {
213 $employee->employer($self);
217 The C<BUILD> method is executed after type constraints are checked, so it is
218 safe to assume that if C<< $self->employees >> has a value, it will be an
219 array reference, and that the elements of that array reference will be
222 We also want to make sure that whenever the C<employees> attribute for
223 a C<Company> is changed, we also update the C<employer> for each
226 To do this we can use an C<after> modifier:
228 after 'employees' => sub {
229 my ( $self, $employees ) = @_;
230 foreach my $employee ( @{ $employees || [] } ) {
231 $employee->employer($self);
235 Again, as with the C<BUILD> method, we know that the type constraint check has
236 already happened, so we know that if C<$employees> is defined it will contain
237 an array reference of C<Employee> objects.
239 The B<Person> class does not really demonstrate anything new. It has several
240 C<required> attributes. It also has a C<predicate> method, which we
241 first used in L<recipe 3|Moose::Cookbook::Basics::Recipe3>.
243 The only new feature in the C<Employee> class is the C<override>
246 override 'full_name' => sub {
248 super() . ', ' . $self->title;
251 This is just a sugary alternative to Perl's built in C<SUPER::>
252 feature. However, there is one difference. You cannot pass any
253 arguments to C<super>. Instead, Moose simply passes the same
254 parameters that were passed to the method.
256 A more detailed example of usage can be found in
257 F<t/recipes/moose_cookbook_basics_recipe4.t>.
261 This recipe was intentionally longer and more complex. It illustrates
262 how Moose classes can be used together with type constraints, as well
263 as the density of information that you can get out of a small amount
264 of typing when using Moose.
266 This recipe also introduced the C<subtype> function, the C<required>
267 attribute, and the C<override> method modifier.
269 We will revisit type constraints in future recipes, and cover type
278 The value being checked is also passed as the first argument to
279 the C<where> block, so it can be accessed as C<$_[0]>.
283 Note that C<ArrayRef[]> will not work. Moose will not parse this as a
284 container type, and instead you will have a new type named
285 "ArrayRef[]", which doesn't make any sense.
289 The C<BUILD> method is actually called by C<< Moose::Object->new >>. It climbs
290 the object inheritance graph and calls any C<BUILD> methods it finds in the
300 sub get_employee_count { scalar @{(shift)->employees} }
303 use Scalar::Util 'isweak';
310 name => 'Infinity Interactive',
311 address => Address->new(
312 street => '565 Plandome Rd., Suite 307',
319 first_name => 'Jeremy',
321 title => 'President / Senior Consultant',
322 address => Address->new(
323 city => 'Manhasset', state => 'NY'
327 first_name => 'Tommy',
329 title => 'Vice President / Senior Developer',
331 Address->new( city => 'New York', state => 'NY' )
334 first_name => 'Stevan',
335 middle_initial => 'C',
336 last_name => 'Little',
337 title => 'Senior Developer',
339 Address->new( city => 'Madison', state => 'CT' )
346 '... created the entire company successfully'
349 isa_ok( $ii, 'Company' );
351 is( $ii->name, 'Infinity Interactive',
352 '... got the right name for the company' );
354 isa_ok( $ii->address, 'Address' );
355 is( $ii->address->street, '565 Plandome Rd., Suite 307',
356 '... got the right street address' );
357 is( $ii->address->city, 'Manhasset', '... got the right city' );
358 is( $ii->address->state, 'NY', '... got the right state' );
359 is( $ii->address->zip_code, 11030, '... got the zip code' );
361 is( $ii->get_employee_count, 3, '... got the right employee count' );
365 isa_ok( $ii->employees->[0], 'Employee' );
366 isa_ok( $ii->employees->[0], 'Person' );
368 is( $ii->employees->[0]->first_name, 'Jeremy',
369 '... got the right first name' );
370 is( $ii->employees->[0]->last_name, 'Shao', '... got the right last name' );
371 ok( !$ii->employees->[0]->has_middle_initial, '... no middle initial' );
372 is( $ii->employees->[0]->middle_initial, undef,
373 '... got the right middle initial value' );
374 is( $ii->employees->[0]->full_name,
375 'Jeremy Shao, President / Senior Consultant',
376 '... got the right full name' );
377 is( $ii->employees->[0]->title, 'President / Senior Consultant',
378 '... got the right title' );
379 is( $ii->employees->[0]->employer, $ii, '... got the right company' );
380 ok( isweak( $ii->employees->[0]->{employer} ),
381 '... the company is a weak-ref' );
383 isa_ok( $ii->employees->[0]->address, 'Address' );
384 is( $ii->employees->[0]->address->city, 'Manhasset',
385 '... got the right city' );
386 is( $ii->employees->[0]->address->state, 'NY', '... got the right state' );
390 isa_ok( $ii->employees->[1], 'Employee' );
391 isa_ok( $ii->employees->[1], 'Person' );
393 is( $ii->employees->[1]->first_name, 'Tommy',
394 '... got the right first name' );
395 is( $ii->employees->[1]->last_name, 'Lee', '... got the right last name' );
396 ok( !$ii->employees->[1]->has_middle_initial, '... no middle initial' );
397 is( $ii->employees->[1]->middle_initial, undef,
398 '... got the right middle initial value' );
399 is( $ii->employees->[1]->full_name,
400 'Tommy Lee, Vice President / Senior Developer',
401 '... got the right full name' );
402 is( $ii->employees->[1]->title, 'Vice President / Senior Developer',
403 '... got the right title' );
404 is( $ii->employees->[1]->employer, $ii, '... got the right company' );
405 ok( isweak( $ii->employees->[1]->{employer} ),
406 '... the company is a weak-ref' );
408 isa_ok( $ii->employees->[1]->address, 'Address' );
409 is( $ii->employees->[1]->address->city, 'New York',
410 '... got the right city' );
411 is( $ii->employees->[1]->address->state, 'NY', '... got the right state' );
415 isa_ok( $ii->employees->[2], 'Employee' );
416 isa_ok( $ii->employees->[2], 'Person' );
418 is( $ii->employees->[2]->first_name, 'Stevan',
419 '... got the right first name' );
420 is( $ii->employees->[2]->last_name, 'Little', '... got the right last name' );
421 ok( $ii->employees->[2]->has_middle_initial, '... got middle initial' );
422 is( $ii->employees->[2]->middle_initial, 'C',
423 '... got the right middle initial value' );
424 is( $ii->employees->[2]->full_name, 'Stevan C. Little, Senior Developer',
425 '... got the right full name' );
426 is( $ii->employees->[2]->title, 'Senior Developer',
427 '... got the right title' );
428 is( $ii->employees->[2]->employer, $ii, '... got the right company' );
429 ok( isweak( $ii->employees->[2]->{employer} ),
430 '... the company is a weak-ref' );
432 isa_ok( $ii->employees->[2]->address, 'Address' );
433 is( $ii->employees->[2]->address->city, 'Madison', '... got the right city' );
434 is( $ii->employees->[2]->address->state, 'CT', '... got the right state' );
439 = Company->new( name => 'Infinity Interactive International' );
440 isa_ok( $new_company, 'Company' );
442 my $ii_employees = $ii->employees;
443 foreach my $employee (@$ii_employees) {
444 is( $employee->employer, $ii, '... has the ii company' );
447 $new_company->employees($ii_employees);
449 foreach my $employee ( @{ $new_company->employees } ) {
450 is( $employee->employer, $new_company,
451 '... has the different company now' );
454 ## check some error conditions for the subtypes
458 Address->new( street => {} ),;
461 '... we die correctly with bad args'
466 Address->new( city => {} ),;
469 '... we die correctly with bad args'
474 Address->new( state => 'British Columbia' ),;
477 '... we die correctly with bad args'
482 Address->new( state => 'Connecticut' ),;
485 '... we live correctly with good args'
490 Address->new( zip_code => 'AF5J6$' ),;
493 '... we die correctly with bad args'
498 Address->new( zip_code => '06443' ),;
501 '... we live correctly with good args'
509 '... we die correctly without good args'
514 Company->new( name => 'Foo' ),;
517 '... we live correctly without good args'
522 Company->new( name => 'Foo', employees => [ Person->new ] ),;
525 '... we die correctly with good args'
530 Company->new( name => 'Foo', employees => [] ),;
533 '... we live correctly with good args'