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. This 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 pseudo-namespacing in real applications,
154 like C<MyApp.Type.USState>.
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 defined a C<BUILD> method, it will be called immediately after an
201 object construction, but before the object is returned to the caller
204 The C<Company> class uses the C<BUILD> method to ensure that each
205 employee of a company has the proper C<Company> object in its
206 C<employer> attribute:
209 my ( $self, $params ) = @_;
210 foreach my $employee ( @{ $self->employees || [] } ) {
211 $employee->employer($self);
215 The C<BUILD> method is executed after type constraints are checked, so it is
216 safe to assume that if C<< $self->employees >> has a value, it will be an
217 array reference, and that the elements of that array reference will be
220 We also want to make sure that whenever the C<employees> attribute for
221 a C<Company> is changed, we also update the C<employer> for each
224 To do this we can use an C<after> modifier:
226 after 'employees' => sub {
227 my ( $self, $employees ) = @_;
228 foreach my $employee ( @{ $employees || [] } ) {
229 $employee->employer($self);
233 Again, as with the C<BUILD> method, we know that the type constraint check has
234 already happened, so we know that if C<$employees> is defined it will contain
235 an array reference of C<Employee> objects..
237 The B<Person> class does not really demonstrate anything new. It has several
238 C<required> attributes. It also has a C<predicate> method, which we
239 first used in L<recipe 3|Moose::Cookbook::Basics::Recipe3>.
241 The only new feature in the C<Employee> class is the C<override>
244 override 'full_name' => sub {
246 super() . ', ' . $self->title;
249 This is just a sugary alternative to Perl's built in C<SUPER::>
250 feature. However, there is one difference. You cannot pass any
251 arguments to C<super>. Instead, Moose simply passes the same
252 parameters that were passed to the method.
254 A more detailed example of usage can be found in
255 F<t/000_recipes/moose_cookbook_basics_recipe4.t>.
259 This recipe was intentionally longer and more complex. It illustrates
260 how Moose classes can be used together with type constraints, as well
261 as the density of information that you can get out of a small amount
262 of typing when using Moose.
264 This recipe also introduced the C<subtype> function, the C<required>
265 attribute, and the C<override> method modifier.
267 We will revisit type constraints in future recipes, and cover type
276 The value being checked is also passed as the first argument to
277 the C<where> block, so it can be accessed as C<$_[0]>.
281 Note that C<ArrayRef[]> will not work. Moose will not parse this as a
282 container type, and instead you will have a new type named
283 "ArrayRef[]", which doesn't make any sense.
287 The C<BUILD> method is actually called by C<< Moose::Object->BUILDALL
288 >>, which is called by C<< Moose::Object->new >>. The C<BUILDALL>
289 method climbs the object inheritance graph and calls any C<BUILD>
290 methods it finds in the correct order.
299 sub get_employee_count { scalar @{(shift)->employees} }
302 use Scalar::Util 'isweak';
309 name => 'Infinity Interactive',
310 address => Address->new(
311 street => '565 Plandome Rd., Suite 307',
318 first_name => 'Jeremy',
320 title => 'President / Senior Consultant',
321 address => Address->new(
322 city => 'Manhasset', state => 'NY'
326 first_name => 'Tommy',
328 title => 'Vice President / Senior Developer',
330 Address->new( city => 'New York', state => 'NY' )
333 first_name => 'Stevan',
334 middle_initial => 'C',
335 last_name => 'Little',
336 title => 'Senior Developer',
338 Address->new( city => 'Madison', state => 'CT' )
345 '... created the entire company successfully'
348 isa_ok( $ii, 'Company' );
350 is( $ii->name, 'Infinity Interactive',
351 '... got the right name for the company' );
353 isa_ok( $ii->address, 'Address' );
354 is( $ii->address->street, '565 Plandome Rd., Suite 307',
355 '... got the right street address' );
356 is( $ii->address->city, 'Manhasset', '... got the right city' );
357 is( $ii->address->state, 'NY', '... got the right state' );
358 is( $ii->address->zip_code, 11030, '... got the zip code' );
360 is( $ii->get_employee_count, 3, '... got the right employee count' );
364 isa_ok( $ii->employees->[0], 'Employee' );
365 isa_ok( $ii->employees->[0], 'Person' );
367 is( $ii->employees->[0]->first_name, 'Jeremy',
368 '... got the right first name' );
369 is( $ii->employees->[0]->last_name, 'Shao', '... got the right last name' );
370 ok( !$ii->employees->[0]->has_middle_initial, '... no middle initial' );
371 is( $ii->employees->[0]->middle_initial, undef,
372 '... got the right middle initial value' );
373 is( $ii->employees->[0]->full_name,
374 'Jeremy Shao, President / Senior Consultant',
375 '... got the right full name' );
376 is( $ii->employees->[0]->title, 'President / Senior Consultant',
377 '... got the right title' );
378 is( $ii->employees->[0]->employer, $ii, '... got the right company' );
379 ok( isweak( $ii->employees->[0]->{employer} ),
380 '... the company is a weak-ref' );
382 isa_ok( $ii->employees->[0]->address, 'Address' );
383 is( $ii->employees->[0]->address->city, 'Manhasset',
384 '... got the right city' );
385 is( $ii->employees->[0]->address->state, 'NY', '... got the right state' );
389 isa_ok( $ii->employees->[1], 'Employee' );
390 isa_ok( $ii->employees->[1], 'Person' );
392 is( $ii->employees->[1]->first_name, 'Tommy',
393 '... got the right first name' );
394 is( $ii->employees->[1]->last_name, 'Lee', '... got the right last name' );
395 ok( !$ii->employees->[1]->has_middle_initial, '... no middle initial' );
396 is( $ii->employees->[1]->middle_initial, undef,
397 '... got the right middle initial value' );
398 is( $ii->employees->[1]->full_name,
399 'Tommy Lee, Vice President / Senior Developer',
400 '... got the right full name' );
401 is( $ii->employees->[1]->title, 'Vice President / Senior Developer',
402 '... got the right title' );
403 is( $ii->employees->[1]->employer, $ii, '... got the right company' );
404 ok( isweak( $ii->employees->[1]->{employer} ),
405 '... the company is a weak-ref' );
407 isa_ok( $ii->employees->[1]->address, 'Address' );
408 is( $ii->employees->[1]->address->city, 'New York',
409 '... got the right city' );
410 is( $ii->employees->[1]->address->state, 'NY', '... got the right state' );
414 isa_ok( $ii->employees->[2], 'Employee' );
415 isa_ok( $ii->employees->[2], 'Person' );
417 is( $ii->employees->[2]->first_name, 'Stevan',
418 '... got the right first name' );
419 is( $ii->employees->[2]->last_name, 'Little', '... got the right last name' );
420 ok( $ii->employees->[2]->has_middle_initial, '... got middle initial' );
421 is( $ii->employees->[2]->middle_initial, 'C',
422 '... got the right middle initial value' );
423 is( $ii->employees->[2]->full_name, 'Stevan C. Little, Senior Developer',
424 '... got the right full name' );
425 is( $ii->employees->[2]->title, 'Senior Developer',
426 '... got the right title' );
427 is( $ii->employees->[2]->employer, $ii, '... got the right company' );
428 ok( isweak( $ii->employees->[2]->{employer} ),
429 '... the company is a weak-ref' );
431 isa_ok( $ii->employees->[2]->address, 'Address' );
432 is( $ii->employees->[2]->address->city, 'Madison', '... got the right city' );
433 is( $ii->employees->[2]->address->state, 'CT', '... got the right state' );
438 = Company->new( name => 'Infinity Interactive International' );
439 isa_ok( $new_company, 'Company' );
441 my $ii_employees = $ii->employees;
442 foreach my $employee (@$ii_employees) {
443 is( $employee->employer, $ii, '... has the ii company' );
446 $new_company->employees($ii_employees);
448 foreach my $employee ( @{ $new_company->employees } ) {
449 is( $employee->employer, $new_company,
450 '... has the different company now' );
453 ## check some error conditions for the subtypes
457 Address->new( street => {} ),;
460 '... we die correctly with bad args'
465 Address->new( city => {} ),;
468 '... we die correctly with bad args'
473 Address->new( state => 'British Columbia' ),;
476 '... we die correctly with bad args'
481 Address->new( state => 'Connecticut' ),;
484 '... we live correctly with good args'
489 Address->new( zip_code => 'AF5J6$' ),;
492 '... we die correctly with bad args'
497 Address->new( zip_code => '06443' ),;
500 '... we live correctly with good args'
508 '... we die correctly without good args'
513 Company->new( name => 'Foo' ),;
516 '... we live correctly without good args'
521 Company->new( name => 'Foo', employees => [ Person->new ] ),;
524 '... we die correctly with good args'
529 Company->new( name => 'Foo', employees => [] ),;
532 '... we live correctly with good args'