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

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NAME

6       Class::MakeMethods::Composite::Inheritable - Overridable data
7

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 Class::MakeMethods::Utility::Inheritable
56       for more about this type of "inheritable" or overridable" data.
57
58       Class::MakeMethods Calling Interface
59
60       When you "use" this package, the method declarations you provide as
61       arguments cause subroutines to be generated and installed in your mod‐
62       ule.
63
64       See "Calling Conventions" in Class::MakeMethods::Standard for more
65       information.
66
67       Class::MakeMethods::Standard Declaration Syntax
68
69       To declare methods, pass in pairs of a method-type name followed by one
70       or more method names.
71
72       See the "METHOD GENERATOR TYPES" section below for a list of the sup‐
73       ported values of generator_type.
74
75       See "Declaration Syntax" in Class::MakeMethods::Standard and "Parameter
76       Syntax" in Class::MakeMethods::Standard for more information.
77

METHOD GENERATOR TYPES

79       scalar - Overrideable Accessor
80
81       For each method name passed, uses a closure to generate a subroutine
82       with the following characteristics:
83
84       ·   May be called as a class or instance method, on the declaring class
85           or any subclass.
86
87       ·   If called without any arguments returns the current value for the
88           callee. If the callee has not had a value defined for this method,
89           searches up from instance to class, and from class to superclass,
90           until a callee with a value is located.
91
92       ·   If called with an argument, stores that as the value associated
93           with the callee, whether instance or class, and returns it,
94
95       ·   If called with multiple arguments, stores a reference to a new
96           array with those arguments as contents, and returns that array ref‐
97           erence.
98
99       Sample declaration and usage:
100
101         package MyClass;
102         use Class::MakeMethods::Composite::Inheritable (
103           scalar => 'foo',
104         );
105         ...
106
107         # Store value
108         MyClass->foo('Foozle');
109
110         # Retrieve value
111         print MyClass->foo;
112
113       array - Overrideable Ref Accessor
114
115       For each method name passed, uses a closure to generate a subroutine
116       with the following characteristics:
117
118       ·   May be called as a class method, or on any instance or subclass,
119           Must be called on a hash-based instance.
120
121       ·   The class value will be a reference to an array (or undef).
122
123       ·   If called without any arguments, returns the current array-ref
124           value (or undef).
125
126       ·   If called with a single non-ref argument, uses that argument as an
127           index to retrieve from the referenced array, and returns that value
128           (or undef).
129
130       ·   If called with a single array ref argument, uses that list to
131           return a slice of the referenced array.
132
133       ·   If called with a list of argument pairs, each with a non-ref index
134           and an associated value, stores the value at the given index in the
135           referenced array. If the class value was previously undefined, a
136           new array is autovivified. The current value in each position will
137           be overwritten, and later arguments with the same index will over‐
138           ride earlier ones. Returns the current array-ref value.
139
140       ·   If called with a list of argument pairs, each with the first item
141           being a reference to an array of up to two numbers, loops over each
142           pair and uses those numbers to splice the value array.
143
144           The first controlling number is the position at which the splice
145           will begin. Zero will start before the first item in the list. Neg‐
146           ative numbers count backwards from the end of the array.
147
148           The second number is the number of items to be removed from the
149           list. If it is omitted, or undefined, or zero, no items are
150           removed. If it is a positive integer, that many items will be
151           returned.
152
153           If both numbers are omitted, or are both undefined, they default to
154           containing the entire value array.
155
156           If the second argument is undef, no values will be inserted; if it
157           is a non-reference value, that one value will be inserted; if it is
158           an array-ref, its values will be copied.
159
160           The method returns the items that removed from the array, if any.
161
162       Sample declaration and usage:
163
164         package MyClass;
165         use Class::MakeMethods::Composite::Inheritable (
166           array => 'bar',
167         );
168         ...
169
170         # Clear and set contents of list
171         print MyClass->bar([ 'Spume', 'Frost' ] );
172
173         # Set values by position
174         MyClass->bar(0 => 'Foozle', 1 => 'Bang!');
175
176         # Positions may be overwritten, and in any order
177         MyClass->bar(2 => 'And Mash', 1 => 'Blah!');
178
179         # Retrieve value by position
180         print MyClass->bar(1);
181
182         # Direct access to referenced array
183         print scalar @{ MyClass->bar() };
184
185       There are also calling conventions for slice and splice operations:
186
187         # Retrieve slice of values by position
188         print join(', ', MyClass->bar( undef, [0, 2] ) );
189
190         # Insert an item at position in the array
191         MyClass->bar([3], 'Potatoes' );
192
193         # Remove 1 item from position 3 in the array
194         MyClass->bar([3, 1], undef );
195
196         # Set a new value at position 2, and return the old value
197         print MyClass->bar([2, 1], 'Froth' );
198
199       NOTE: THIS METHOD GENERATOR HAS NOT BEEN WRITTEN YET.
200
201       hash - Overrideable Ref Accessor
202
203       For each method name passed, uses a closure to generate a subroutine
204       with the following characteristics:
205
206       ·   May be called as a class method, or on any instance or subclass,
207           Must be called on a hash-based instance.
208
209       ·   The class value will be a reference to a hash (or undef).
210
211       ·   If called without any arguments returns the contents of the hash in
212           list context, or a hash reference in scalar context for the callee.
213           If the callee has not had a value defined for this method, searches
214           up from instance to class, and from class to superclass, until a
215           callee with a value is located.
216
217       ·   If called with one non-ref argument, uses that argument as an index
218           to retrieve from the referenced hash, and returns that value (or
219           undef). If the callee has not had a value defined for this method,
220           searches up from instance to class, and from class to superclass,
221           until a callee with a value is located.
222
223       ·   If called with one array-ref argument, uses the contents of that
224           array to retrieve a slice of the referenced hash. If the callee has
225           not had a value defined for this method, searches up from instance
226           to class, and from class to superclass, until a callee with a value
227           is located.
228
229       ·   If called with one hash-ref argument, sets the contents of the ref‐
230           erenced hash to match that provided.
231
232       ·   If called with a list of key-value pairs, stores the value under
233           the given key in the hash associated with the callee, whether
234           instance or class. If the callee did not previously have a hash-ref
235           value associated with it, searches up instance to class, and from
236           class to superclass, until a callee with a value is located, and
237           copies that hash before making the assignments. The current value
238           under each key will be overwritten, and later arguments with the
239           same key will override earlier ones. Returns the contents of the
240           hash in list context, or a hash reference in scalar context.
241
242       Sample declaration and usage:
243
244         package MyClass;
245         use Class::MakeMethods::Composite::Inheritable (
246           hash => 'baz',
247         );
248         ...
249
250         # Set values by key
251         MyClass->baz('foo' => 'Foozle', 'bar' => 'Bang!');
252
253         # Values may be overwritten, and in any order
254         MyClass->baz('broccoli' => 'Blah!', 'foo' => 'Fiddle');
255
256         # Retrieve value by key
257         print MyClass->baz('foo');
258
259         # Retrive slice of values by position
260         print join(', ', MyClass->baz( ['foo', 'bar'] ) );
261
262         # Direct access to referenced hash
263         print keys %{ MyClass->baz() };
264
265         # Reset the hash contents to empty
266         @{ MyClass->baz() } = ();
267
268       NOTE: THIS METHOD GENERATOR IS INCOMPLETE.
269
270       hook - Overrideable array of subroutines
271
272       A hook method is called from the outside as a normal method. However,
273       internally, it contains an array of subroutine references, each of
274       which are called in turn to produce the method's results.
275
276       Subroutines may be added to the hook's array by calling it with a
277       blessed subroutine reference, as shown below. Subroutines may be added
278       on a class-wide basis or on an individual object.
279
280       You might want to use this type of method to provide an easy way for
281       callbacks to be registered.
282
283         package MyClass;
284         use Class::MakeMethods::Composite::Inheritable ( 'hook' => 'init' );
285
286         MyClass->init( Class::MakeMethods::Composite::Inheritable->Hook( sub {
287             my $callee = shift;
288             warn "Init...";
289         } );
290
291         my $obj = MyClass->new;
292         $obj->init();
293
294       object - Overrideable Ref Accessor
295
296       For each method name passed, uses a closure to generate a subroutine
297       with the following characteristics:
298
299       ·   May be called as a class method, or on any instance or subclass,
300           Must be called on a hash-based instance.
301
302       ·   The class value will be a reference to an object (or undef).
303
304       ·   If called without any arguments returns the current value for the
305           callee. If the callee has not had a value defined for this method,
306           searches up from instance to class, and from class to superclass,
307           until a callee with a value is located.
308
309       ·   If called with an argument, stores that as the value associated
310           with the callee, whether instance or class, and returns it,
311
312       Sample declaration and usage:
313
314         package MyClass;
315         use Class::MakeMethods::Composite::Inheritable (
316           object => 'foo',
317         );
318         ...
319
320         # Store value
321         MyClass->foo( Foozle->new() );
322
323         # Retrieve value
324         print MyClass->foo;
325
326       NOTE: THIS METHOD GENERATOR HAS NOT BEEN WRITTEN YET.
327

NAME

SYNOPSIS

DESCRIPTION

METHOD GENERATOR TYPES

SEE ALSO