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1 | package Moose::Cookbook::Basics::Recipe4; |
2 | |
3 | # ABSTRACT: Subtypes, and modeling a simple B<Company> class hierarchy |
4 | |
5 | __END__ |
6 | |
471c4f09 |
7 | |
8 | =pod |
9 | |
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10 | =begin testing-SETUP |
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11 | |
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12 | use Test::Requires { |
13 | 'Locale::US' => '0', |
14 | 'Regexp::Common' => '0', |
15 | }; |
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16 | |
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17 | =end testing-SETUP |
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18 | |
471c4f09 |
19 | =head1 SYNOPSIS |
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20 | |
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21 | package Address; |
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22 | use Moose; |
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23 | use Moose::Util::TypeConstraints; |
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24 | |
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25 | use Locale::US; |
26 | use Regexp::Common 'zip'; |
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27 | |
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28 | my $STATES = Locale::US->new; |
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29 | subtype 'USState' |
471c4f09 |
30 | => as Str |
31 | => where { |
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32 | ( exists $STATES->{code2state}{ uc($_) } |
33 | || exists $STATES->{state2code}{ uc($_) } ); |
34 | }; |
35 | |
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36 | subtype 'USZipCode' |
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37 | => as Value |
38 | => where { |
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39 | /^$RE{zip}{US}{-extended => 'allow'}$/; |
40 | }; |
41 | |
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' ); |
46 | |
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47 | package Company; |
48 | use Moose; |
49 | use Moose::Util::TypeConstraints; |
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50 | |
51 | has 'name' => ( is => 'rw', isa => 'Str', required => 1 ); |
52 | has 'address' => ( is => 'rw', isa => 'Address' ); |
53 | has 'employees' => ( is => 'rw', isa => 'ArrayRef[Employee]' ); |
54 | |
f1917f58 |
55 | sub BUILD { |
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56 | my ( $self, $params ) = @_; |
922a97e9 |
57 | foreach my $employee ( @{ $self->employees || [] } ) { |
58 | $employee->employer($self); |
f1917f58 |
59 | } |
60 | } |
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61 | |
f1917f58 |
62 | after 'employees' => sub { |
36c99105 |
63 | my ( $self, $employees ) = @_; |
922a97e9 |
64 | foreach my $employee ( @{ $employees || [] } ) { |
65 | $employee->employer($self); |
f1917f58 |
66 | } |
36c99105 |
67 | }; |
68 | |
471c4f09 |
69 | package Person; |
471c4f09 |
70 | use Moose; |
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71 | |
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' |
77 | ); |
78 | has 'address' => ( is => 'rw', isa => 'Address' ); |
79 | |
471c4f09 |
80 | sub full_name { |
81 | my $self = shift; |
36c99105 |
82 | return $self->first_name |
83 | . ( |
84 | $self->has_middle_initial |
85 | ? ' ' . $self->middle_initial . '. ' |
86 | : ' ' |
87 | ) . $self->last_name; |
471c4f09 |
88 | } |
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89 | |
471c4f09 |
90 | package Employee; |
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91 | use Moose; |
92 | |
471c4f09 |
93 | extends 'Person'; |
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94 | |
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95 | has 'title' => ( is => 'rw', isa => 'Str', required => 1 ); |
96 | has 'employer' => ( is => 'rw', isa => 'Company', weak_ref => 1 ); |
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97 | |
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98 | override 'full_name' => sub { |
99 | my $self = shift; |
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100 | super() . ', ' . $self->title; |
471c4f09 |
101 | }; |
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102 | |
471c4f09 |
103 | =head1 DESCRIPTION |
104 | |
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105 | This recipe introduces the C<subtype> sugar function from |
106 | L<Moose::Util::TypeConstraints>. The C<subtype> function lets you |
107 | declaratively create type constraints without building an entire |
108 | class. |
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109 | |
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110 | In the recipe we also make use of L<Locale::US> and L<Regexp::Common> |
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111 | to build constraints, showing how constraints can make use of existing |
112 | CPAN tools for data validation. |
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113 | |
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114 | Finally, we introduce the C<required> attribute option. |
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115 | |
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116 | In the C<Address> class we define two subtypes. The first uses the |
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117 | L<Locale::US> module to check the validity of a state. It accepts |
4a6b74bd |
118 | either a state abbreviation of full name. |
119 | |
120 | A state will be passed in as a string, so we make our C<USState> type |
121 | a subtype of Moose's builtin C<Str> type. This is done using the C<as> |
122 | sugar. The actual constraint is defined using C<where>. This function |
123 | accepts a single subroutine reference. That subroutine will be called |
124 | with the value to be checked in C<$_> (1). It is expected to return a |
125 | true or false value indicating whether the value is valid for the |
126 | type. |
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127 | |
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128 | We can now use the C<USState> type just like Moose's builtin types: |
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129 | |
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130 | has 'state' => ( is => 'rw', isa => 'USState' ); |
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131 | |
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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 |
134 | thrown. |
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135 | |
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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. |
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139 | |
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140 | subtype 'USZipCode' |
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141 | => as Value |
142 | => where { |
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143 | /^$RE{zip}{US}{-extended => 'allow'}$/; |
144 | }; |
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145 | |
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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. |
149 | |
150 | The type constraints we created are reusable. Type constraints are |
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151 | stored by name in a global registry, which means that we can refer to |
4a6b74bd |
152 | them in other classes. Because the registry is global, we do recommend |
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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). |
4a6b74bd |
155 | |
156 | These two subtypes allow us to define a simple C<Address> class. |
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157 | |
4a6b74bd |
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: |
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162 | |
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163 | has 'address' => ( is => 'rw', isa => 'Address' ); |
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164 | |
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165 | A company also needs a name: |
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166 | |
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167 | has 'name' => ( is => 'rw', isa => 'Str', required => 1 ); |
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168 | |
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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. |
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174 | |
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175 | The next attribute, C<employees>, uses a I<parameterized> type |
176 | constraint: |
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177 | |
178 | has 'employees' => ( is => 'rw', isa => 'ArrayRef[Employee]' ); |
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179 | |
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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 |
183 | constraint. |
184 | |
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185 | Parameterizable type constraints (or "container types"), such as |
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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) |
190 | |
191 | If you jump down to the definition of the C<Employee> class, you will |
192 | see that it has an C<employer> attribute. |
193 | |
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. |
197 | |
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 |
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200 | defines a C<BUILD> method, it will be called immediately after |
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201 | object construction, but before the object is returned to the caller |
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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. |
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205 | |
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: |
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209 | |
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210 | sub BUILD { |
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211 | my ( $self, $params ) = @_; |
922a97e9 |
212 | foreach my $employee ( @{ $self->employees || [] } ) { |
213 | $employee->employer($self); |
ad5ed80c |
214 | } |
215 | } |
216 | |
922a97e9 |
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 |
220 | C<Employee> objects. |
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221 | |
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 |
224 | employee. |
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225 | |
4a6b74bd |
226 | To do this we can use an C<after> modifier: |
ad5ed80c |
227 | |
228 | after 'employees' => sub { |
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229 | my ( $self, $employees ) = @_; |
922a97e9 |
230 | foreach my $employee ( @{ $employees || [] } ) { |
231 | $employee->employer($self); |
ad5ed80c |
232 | } |
233 | }; |
234 | |
922a97e9 |
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 |
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237 | an array reference of C<Employee> objects. |
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238 | |
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239 | The B<Person> class does not really demonstrate anything new. It has several |
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240 | C<required> attributes. It also has a C<predicate> method, which we |
241 | first used in L<recipe 3|Moose::Cookbook::Basics::Recipe3>. |
f1917f58 |
242 | |
4a6b74bd |
243 | The only new feature in the C<Employee> class is the C<override> |
244 | method modifier: |
f1917f58 |
245 | |
246 | override 'full_name' => sub { |
247 | my $self = shift; |
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248 | super() . ', ' . $self->title; |
f1917f58 |
249 | }; |
250 | |
4a6b74bd |
251 | This is just a sugary alternative to Perl's built in C<SUPER::> |
252 | feature. However, there is one difference. You cannot pass any |
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253 | arguments to C<super>. Instead, Moose simply passes the same |
4a6b74bd |
254 | parameters that were passed to the method. |
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255 | |
4a6b74bd |
256 | A more detailed example of usage can be found in |
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257 | F<t/recipes/moose_cookbook_basics_recipe4.t>. |
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258 | |
259 | =head1 CONCLUSION |
260 | |
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261 | This recipe was intentionally longer and more complex. It illustrates |
262 | how Moose classes can be used together with type constraints, as well |
263 | as the density of information that you can get out of a small amount |
264 | of typing when using Moose. |
265 | |
266 | This recipe also introduced the C<subtype> function, the C<required> |
267 | attribute, and the C<override> method modifier. |
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268 | |
4a6b74bd |
269 | We will revisit type constraints in future recipes, and cover type |
270 | coercion as well. |
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271 | |
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272 | =head1 FOOTNOTES |
273 | |
274 | =over 4 |
275 | |
276 | =item (1) |
277 | |
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278 | The value being checked is also passed as the first argument to |
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279 | the C<where> block, so it can be accessed as C<$_[0]>. |
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280 | |
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281 | =item (2) |
282 | |
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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. |
286 | |
287 | =item (3) |
288 | |
c25e358a |
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 |
291 | correct order. |
ad5ed80c |
292 | |
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293 | =back |
294 | |
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295 | =begin testing |
296 | |
297 | { |
298 | package Company; |
299 | |
300 | sub get_employee_count { scalar @{(shift)->employees} } |
301 | } |
302 | |
303 | use Scalar::Util 'isweak'; |
304 | |
305 | my $ii; |
b10dde3a |
306 | is( |
307 | exception { |
308 | $ii = Company->new( |
309 | { |
310 | name => 'Infinity Interactive', |
311 | address => Address->new( |
312 | street => '565 Plandome Rd., Suite 307', |
313 | city => 'Manhasset', |
314 | state => 'NY', |
315 | zip_code => '11030' |
c79239a2 |
316 | ), |
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317 | employees => [ |
318 | Employee->new( |
319 | first_name => 'Jeremy', |
320 | last_name => 'Shao', |
321 | title => 'President / Senior Consultant', |
322 | address => Address->new( |
323 | city => 'Manhasset', state => 'NY' |
324 | ) |
325 | ), |
326 | Employee->new( |
327 | first_name => 'Tommy', |
328 | last_name => 'Lee', |
329 | title => 'Vice President / Senior Developer', |
330 | address => |
331 | Address->new( city => 'New York', state => 'NY' ) |
332 | ), |
333 | Employee->new( |
334 | first_name => 'Stevan', |
335 | middle_initial => 'C', |
336 | last_name => 'Little', |
337 | title => 'Senior Developer', |
338 | address => |
339 | Address->new( city => 'Madison', state => 'CT' ) |
340 | ), |
341 | ] |
342 | } |
343 | ); |
344 | }, |
345 | undef, |
346 | '... created the entire company successfully' |
347 | ); |
348 | |
c79239a2 |
349 | isa_ok( $ii, 'Company' ); |
350 | |
351 | is( $ii->name, 'Infinity Interactive', |
352 | '... got the right name for the company' ); |
353 | |
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' ); |
360 | |
361 | is( $ii->get_employee_count, 3, '... got the right employee count' ); |
362 | |
363 | # employee #1 |
364 | |
365 | isa_ok( $ii->employees->[0], 'Employee' ); |
366 | isa_ok( $ii->employees->[0], 'Person' ); |
367 | |
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' ); |
382 | |
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' ); |
387 | |
388 | # employee #2 |
389 | |
390 | isa_ok( $ii->employees->[1], 'Employee' ); |
391 | isa_ok( $ii->employees->[1], 'Person' ); |
392 | |
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' ); |
407 | |
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' ); |
412 | |
413 | # employee #3 |
414 | |
415 | isa_ok( $ii->employees->[2], 'Employee' ); |
416 | isa_ok( $ii->employees->[2], 'Person' ); |
417 | |
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' ); |
431 | |
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' ); |
435 | |
436 | # create new company |
437 | |
438 | my $new_company |
439 | = Company->new( name => 'Infinity Interactive International' ); |
440 | isa_ok( $new_company, 'Company' ); |
441 | |
442 | my $ii_employees = $ii->employees; |
443 | foreach my $employee (@$ii_employees) { |
444 | is( $employee->employer, $ii, '... has the ii company' ); |
445 | } |
446 | |
447 | $new_company->employees($ii_employees); |
448 | |
449 | foreach my $employee ( @{ $new_company->employees } ) { |
450 | is( $employee->employer, $new_company, |
451 | '... has the different company now' ); |
452 | } |
453 | |
454 | ## check some error conditions for the subtypes |
455 | |
b10dde3a |
456 | isnt( |
457 | exception { |
458 | Address->new( street => {} ),; |
459 | }, |
460 | undef, |
461 | '... we die correctly with bad args' |
462 | ); |
463 | |
464 | isnt( |
465 | exception { |
466 | Address->new( city => {} ),; |
467 | }, |
468 | undef, |
469 | '... we die correctly with bad args' |
470 | ); |
471 | |
472 | isnt( |
473 | exception { |
474 | Address->new( state => 'British Columbia' ),; |
475 | }, |
476 | undef, |
477 | '... we die correctly with bad args' |
478 | ); |
479 | |
480 | is( |
481 | exception { |
482 | Address->new( state => 'Connecticut' ),; |
483 | }, |
484 | undef, |
485 | '... we live correctly with good args' |
486 | ); |
487 | |
488 | isnt( |
489 | exception { |
490 | Address->new( zip_code => 'AF5J6$' ),; |
491 | }, |
492 | undef, |
493 | '... we die correctly with bad args' |
494 | ); |
495 | |
496 | is( |
497 | exception { |
498 | Address->new( zip_code => '06443' ),; |
499 | }, |
500 | undef, |
501 | '... we live correctly with good args' |
502 | ); |
503 | |
504 | isnt( |
505 | exception { |
506 | Company->new(),; |
507 | }, |
508 | undef, |
509 | '... we die correctly without good args' |
510 | ); |
511 | |
512 | is( |
513 | exception { |
514 | Company->new( name => 'Foo' ),; |
515 | }, |
516 | undef, |
517 | '... we live correctly without good args' |
518 | ); |
519 | |
520 | isnt( |
521 | exception { |
522 | Company->new( name => 'Foo', employees => [ Person->new ] ),; |
523 | }, |
524 | undef, |
525 | '... we die correctly with good args' |
526 | ); |
527 | |
528 | is( |
529 | exception { |
530 | Company->new( name => 'Foo', employees => [] ),; |
531 | }, |
532 | undef, |
533 | '... we live correctly with good args' |
534 | ); |
c79239a2 |
535 | |
536 | =end testing |
537 | |
e08c54f5 |
538 | =cut |