Class::MakeMethods::Composite::Inheritable(3pm)

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NAME

6       Class::MakeMethods::Composite::Inheritable - Overridable data
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SYNOPSIS

9         package MyClass;
10
11         use Class::MakeMethods( 'Composite::Inheritable:scalar' => 'foo' );
12         # We now have an accessor method for an "inheritable" scalar value
13
14         MyClass->foo( 'Foozle' );   # Set a class-wide value
15         print MyClass->foo();       # Retrieve class-wide value
16
17         my $obj = MyClass->new(...);
18         print $obj->foo();          # All instances "inherit" that value...
19
20         $obj->foo( 'Foible' );      # until you set a value for an instance.
21         print $obj->foo();          # This now finds object-specific value.
22         ...
23
24         package MySubClass;
25         @ISA = 'MyClass';
26
27         print MySubClass->foo();    # Intially same as superclass,
28         MySubClass->foo('Foobar');  # but overridable per subclass,
29         print $subclass_obj->foo(); # and shared by its instances
30         $subclass_obj->foo('Fosil');# until you override them...
31         ...
32
33         # Similar behaviour for hashes and arrays is currently incomplete
34         package MyClass;
35         use Class::MakeMethods::Composite::Inheritable (
36           array => 'my_list',
37           hash => 'my_index',
38         );
39
40         MyClass->my_list(0 => 'Foozle', 1 => 'Bang!');
41         print MyClass->my_list(1);
42
43         MyClass->my_index('broccoli' => 'Blah!', 'foo' => 'Fiddle');
44         print MyClass->my_index('foo');
45

DESCRIPTION

47       The MakeMethods subclass provides accessor methods that search an
48       inheritance tree to find a value. This allows you to set a shared or
49       default value for a given class, optionally override it in a subclass,
50       and then optionally override it on a per-instance basis.
51
52       Note that all MakeMethods methods are inheritable, in the sense that
53       they work as expected for subclasses. These methods are different in
54       that the data accessed by each method can be inherited or overridden in
55       each subclass or instance. See "
56       Class::MakeMethods::Utility::Inheritable" for more about this type of
57       "inheritable" or overridable" data.
58
59   Class::MakeMethods Calling Interface
60       When you "use" this package, the method declarations you provide as
61       arguments cause subroutines to be generated and installed in your
62       module.
63
64       See "Calling Conventions" in Class::MakeMethods::Standard for more
65       information.
66
67   Class::MakeMethods::Standard Declaration Syntax
68       To declare methods, pass in pairs of a method-type name followed by one
69       or more method names.
70
71       See the "METHOD GENERATOR TYPES" section below for a list of the
72       supported values of generator_type.
73
74       See "Declaration Syntax" in Class::MakeMethods::Standard and "Parameter
75       Syntax" in Class::MakeMethods::Standard for more information.
76

METHOD GENERATOR TYPES

78   scalar - Overrideable Accessor
79       For each method name passed, uses a closure to generate a subroutine
80       with the following characteristics:
81
82       ·   May be called as a class or instance method, on the declaring class
83           or any subclass.
84
85       ·   If called without any arguments returns the current value for the
86           callee. If the callee has not had a value defined for this method,
87           searches up from instance to class, and from class to superclass,
88           until a callee with a value is located.
89
90       ·   If called with an argument, stores that as the value associated
91           with the callee, whether instance or class, and returns it,
92
93       ·   If called with multiple arguments, stores a reference to a new
94           array with those arguments as contents, and returns that array
95           reference.
96
97       Sample declaration and usage:
98
99         package MyClass;
100         use Class::MakeMethods::Composite::Inheritable (
101           scalar => 'foo',
102         );
103         ...
104
105         # Store value
106         MyClass->foo('Foozle');
107
108         # Retrieve value
109         print MyClass->foo;
110
111   array - Overrideable Ref Accessor
112       For each method name passed, uses a closure to generate a subroutine
113       with the following characteristics:
114
115       ·   May be called as a class method, or on any instance or subclass,
116           Must be called on a hash-based instance.
117
118       ·   The class value will be a reference to an array (or undef).
119
120       ·   If called without any arguments, returns the current array-ref
121           value (or undef).
122
123       ·   If called with a single non-ref argument, uses that argument as an
124           index to retrieve from the referenced array, and returns that value
125           (or undef).
126
127       ·   If called with a single array ref argument, uses that list to
128           return a slice of the referenced array.
129
130       ·   If called with a list of argument pairs, each with a non-ref index
131           and an associated value, stores the value at the given index in the
132           referenced array. If the class value was previously undefined, a
133           new array is autovivified. The current value in each position will
134           be overwritten, and later arguments with the same index will
135           override earlier ones. Returns the current array-ref value.
136
137       ·   If called with a list of argument pairs, each with the first item
138           being a reference to an array of up to two numbers, loops over each
139           pair and uses those numbers to splice the value array.
140
141           The first controlling number is the position at which the splice
142           will begin. Zero will start before the first item in the list.
143           Negative numbers count backwards from the end of the array.
144
145           The second number is the number of items to be removed from the
146           list. If it is omitted, or undefined, or zero, no items are
147           removed. If it is a positive integer, that many items will be
148           returned.
149
150           If both numbers are omitted, or are both undefined, they default to
151           containing the entire value array.
152
153           If the second argument is undef, no values will be inserted; if it
154           is a non-reference value, that one value will be inserted; if it is
155           an array-ref, its values will be copied.
156
157           The method returns the items that removed from the array, if any.
158
159       Sample declaration and usage:
160
161         package MyClass;
162         use Class::MakeMethods::Composite::Inheritable (
163           array => 'bar',
164         );
165         ...
166
167         # Clear and set contents of list
168         print MyClass->bar([ 'Spume', 'Frost' ] );
169
170         # Set values by position
171         MyClass->bar(0 => 'Foozle', 1 => 'Bang!');
172
173         # Positions may be overwritten, and in any order
174         MyClass->bar(2 => 'And Mash', 1 => 'Blah!');
175
176         # Retrieve value by position
177         print MyClass->bar(1);
178
179         # Direct access to referenced array
180         print scalar @{ MyClass->bar() };
181
182       There are also calling conventions for slice and splice operations:
183
184         # Retrieve slice of values by position
185         print join(', ', MyClass->bar( undef, [0, 2] ) );
186
187         # Insert an item at position in the array
188         MyClass->bar([3], 'Potatoes' );
189
190         # Remove 1 item from position 3 in the array
191         MyClass->bar([3, 1], undef );
192
193         # Set a new value at position 2, and return the old value
194         print MyClass->bar([2, 1], 'Froth' );
195
196       NOTE: THIS METHOD GENERATOR HAS NOT BEEN WRITTEN YET.
197
198   hash - Overrideable Ref Accessor
199       For each method name passed, uses a closure to generate a subroutine
200       with the following characteristics:
201
202       ·   May be called as a class method, or on any instance or subclass,
203           Must be called on a hash-based instance.
204
205       ·   The class value will be a reference to a hash (or undef).
206
207       ·   If called without any arguments returns the contents of the hash in
208           list context, or a hash reference in scalar context for the callee.
209           If the callee has not had a value defined for this method, searches
210           up from instance to class, and from class to superclass, until a
211           callee with a value is located.
212
213       ·   If called with one non-ref argument, uses that argument as an index
214           to retrieve from the referenced hash, and returns that value (or
215           undef). If the callee has not had a value defined for this method,
216           searches up from instance to class, and from class to superclass,
217           until a callee with a value is located.
218
219       ·   If called with one array-ref argument, uses the contents of that
220           array to retrieve a slice of the referenced hash. If the callee has
221           not had a value defined for this method, searches up from instance
222           to class, and from class to superclass, until a callee with a value
223           is located.
224
225       ·   If called with one hash-ref argument, sets the contents of the
226           referenced hash to match that provided.
227
228       ·   If called with a list of key-value pairs, stores the value under
229           the given key in the hash associated with the callee, whether
230           instance or class. If the callee did not previously have a hash-ref
231           value associated with it, searches up instance to class, and from
232           class to superclass, until a callee with a value is located, and
233           copies that hash before making the assignments. The current value
234           under each key will be overwritten, and later arguments with the
235           same key will override earlier ones. Returns the contents of the
236           hash in list context, or a hash reference in scalar context.
237
238       Sample declaration and usage:
239
240         package MyClass;
241         use Class::MakeMethods::Composite::Inheritable (
242           hash => 'baz',
243         );
244         ...
245
246         # Set values by key
247         MyClass->baz('foo' => 'Foozle', 'bar' => 'Bang!');
248
249         # Values may be overwritten, and in any order
250         MyClass->baz('broccoli' => 'Blah!', 'foo' => 'Fiddle');
251
252         # Retrieve value by key
253         print MyClass->baz('foo');
254
255         # Retrive slice of values by position
256         print join(', ', MyClass->baz( ['foo', 'bar'] ) );
257
258         # Direct access to referenced hash
259         print keys %{ MyClass->baz() };
260
261         # Reset the hash contents to empty
262         @{ MyClass->baz() } = ();
263
264       NOTE: THIS METHOD GENERATOR IS INCOMPLETE.
265
266   hook - Overrideable array of subroutines
267       A hook method is called from the outside as a normal method. However,
268       internally, it contains an array of subroutine references, each of
269       which are called in turn to produce the method's results.
270
271       Subroutines may be added to the hook's array by calling it with a
272       blessed subroutine reference, as shown below. Subroutines may be added
273       on a class-wide basis or on an individual object.
274
275       You might want to use this type of method to provide an easy way for
276       callbacks to be registered.
277
278         package MyClass;
279         use Class::MakeMethods::Composite::Inheritable ( 'hook' => 'init' );
280
281         MyClass->init( Class::MakeMethods::Composite::Inheritable->Hook( sub {
282             my $callee = shift;
283             warn "Init...";
284         } );
285
286         my $obj = MyClass->new;
287         $obj->init();
288
289   object - Overrideable Ref Accessor
290       For each method name passed, uses a closure to generate a subroutine
291       with the following characteristics:
292
293       ·   May be called as a class method, or on any instance or subclass,
294           Must be called on a hash-based instance.
295
296       ·   The class value will be a reference to an object (or undef).
297
298       ·   If called without any arguments returns the current value for the
299           callee. If the callee has not had a value defined for this method,
300           searches up from instance to class, and from class to superclass,
301           until a callee with a value is located.
302
303       ·   If called with an argument, stores that as the value associated
304           with the callee, whether instance or class, and returns it,
305
306       Sample declaration and usage:
307
308         package MyClass;
309         use Class::MakeMethods::Composite::Inheritable (
310           object => 'foo',
311         );
312         ...
313
314         # Store value
315         MyClass->foo( Foozle->new() );
316
317         # Retrieve value
318         print MyClass->foo;
319
320       NOTE: THIS METHOD GENERATOR HAS NOT BEEN WRITTEN YET.
321

POD ERRORS

329       Hey! The above document had some coding errors, which are explained
330       below:
331
332       Around line 49:
333           L<> starts or ends with whitespace
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337perl v5.30.0                      2019-07M-a2k6eMethods::Composite::Inheritable(3)

NAME

SYNOPSIS

DESCRIPTION

METHOD GENERATOR TYPES

SEE ALSO

POD ERRORS