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1 | package Class::Struct; |
2 | ||
3 | ## See POD after __END__ | |
4 | ||
5 | use 5.006_001; | |
6 | ||
7 | use strict; | |
8 | use warnings::register; | |
9 | our(@ISA, @EXPORT, $VERSION); | |
10 | ||
11 | use Carp; | |
12 | ||
13 | require Exporter; | |
14 | @ISA = qw(Exporter); | |
15 | @EXPORT = qw(struct); | |
16 | ||
17 | $VERSION = '0.63'; | |
18 | ||
19 | ## Tested on 5.002 and 5.003 without class membership tests: | |
20 | my $CHECK_CLASS_MEMBERSHIP = ($] >= 5.003_95); | |
21 | ||
22 | my $print = 0; | |
23 | sub printem { | |
24 | if (@_) { $print = shift } | |
25 | else { $print++ } | |
26 | } | |
27 | ||
28 | { | |
29 | package Class::Struct::Tie_ISA; | |
30 | ||
31 | sub TIEARRAY { | |
32 | my $class = shift; | |
33 | return bless [], $class; | |
34 | } | |
35 | ||
36 | sub STORE { | |
37 | my ($self, $index, $value) = @_; | |
38 | Class::Struct::_subclass_error(); | |
39 | } | |
40 | ||
41 | sub FETCH { | |
42 | my ($self, $index) = @_; | |
43 | $self->[$index]; | |
44 | } | |
45 | ||
46 | sub FETCHSIZE { | |
47 | my $self = shift; | |
48 | return scalar(@$self); | |
49 | } | |
50 | ||
51 | sub DESTROY { } | |
52 | } | |
53 | ||
54 | sub import { | |
55 | my $self = shift; | |
56 | ||
57 | if ( @_ == 0 ) { | |
58 | $self->export_to_level( 1, $self, @EXPORT ); | |
59 | } elsif ( @_ == 1 ) { | |
60 | # This is admittedly a little bit silly: | |
61 | # do we ever export anything else than 'struct'...? | |
62 | $self->export_to_level( 1, $self, @_ ); | |
63 | } else { | |
64 | goto &struct; | |
65 | } | |
66 | } | |
67 | ||
68 | sub struct { | |
69 | ||
70 | # Determine parameter list structure, one of: | |
71 | # struct( class => [ element-list ]) | |
72 | # struct( class => { element-list }) | |
73 | # struct( element-list ) | |
74 | # Latter form assumes current package name as struct name. | |
75 | ||
76 | my ($class, @decls); | |
77 | my $base_type = ref $_[1]; | |
78 | if ( $base_type eq 'HASH' ) { | |
79 | $class = shift; | |
80 | @decls = %{shift()}; | |
81 | _usage_error() if @_; | |
82 | } | |
83 | elsif ( $base_type eq 'ARRAY' ) { | |
84 | $class = shift; | |
85 | @decls = @{shift()}; | |
86 | _usage_error() if @_; | |
87 | } | |
88 | else { | |
89 | $base_type = 'ARRAY'; | |
90 | $class = (caller())[0]; | |
91 | @decls = @_; | |
92 | } | |
93 | ||
94 | _usage_error() if @decls % 2 == 1; | |
95 | ||
96 | # Ensure we are not, and will not be, a subclass. | |
97 | ||
98 | my $isa = do { | |
99 | no strict 'refs'; | |
100 | \@{$class . '::ISA'}; | |
101 | }; | |
102 | _subclass_error() if @$isa; | |
103 | tie @$isa, 'Class::Struct::Tie_ISA'; | |
104 | ||
105 | # Create constructor. | |
106 | ||
107 | croak "function 'new' already defined in package $class" | |
108 | if do { no strict 'refs'; defined &{$class . "::new"} }; | |
109 | ||
110 | my @methods = (); | |
111 | my %refs = (); | |
112 | my %arrays = (); | |
113 | my %hashes = (); | |
114 | my %classes = (); | |
115 | my $got_class = 0; | |
116 | my $out = ''; | |
117 | ||
118 | $out = "{\n package $class;\n use Carp;\n sub new {\n"; | |
119 | $out .= " my (\$class, \%init) = \@_;\n"; | |
120 | $out .= " \$class = __PACKAGE__ unless \@_;\n"; | |
121 | ||
122 | my $cnt = 0; | |
123 | my $idx = 0; | |
124 | my( $cmt, $name, $type, $elem ); | |
125 | ||
126 | if( $base_type eq 'HASH' ){ | |
127 | $out .= " my(\$r) = {};\n"; | |
128 | $cmt = ''; | |
129 | } | |
130 | elsif( $base_type eq 'ARRAY' ){ | |
131 | $out .= " my(\$r) = [];\n"; | |
132 | } | |
133 | while( $idx < @decls ){ | |
134 | $name = $decls[$idx]; | |
135 | $type = $decls[$idx+1]; | |
136 | push( @methods, $name ); | |
137 | if( $base_type eq 'HASH' ){ | |
138 | $elem = "{'${class}::$name'}"; | |
139 | } | |
140 | elsif( $base_type eq 'ARRAY' ){ | |
141 | $elem = "[$cnt]"; | |
142 | ++$cnt; | |
143 | $cmt = " # $name"; | |
144 | } | |
145 | if( $type =~ /^\*(.)/ ){ | |
146 | $refs{$name}++; | |
147 | $type = $1; | |
148 | } | |
149 | my $init = "defined(\$init{'$name'}) ? \$init{'$name'} :"; | |
150 | if( $type eq '@' ){ | |
151 | $out .= " croak 'Initializer for $name must be array reference'\n"; | |
152 | $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'ARRAY';\n"; | |
153 | $out .= " \$r->$elem = $init [];$cmt\n"; | |
154 | $arrays{$name}++; | |
155 | } | |
156 | elsif( $type eq '%' ){ | |
157 | $out .= " croak 'Initializer for $name must be hash reference'\n"; | |
158 | $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'HASH';\n"; | |
159 | $out .= " \$r->$elem = $init {};$cmt\n"; | |
160 | $hashes{$name}++; | |
161 | } | |
162 | elsif ( $type eq '$') { | |
163 | $out .= " \$r->$elem = $init undef;$cmt\n"; | |
164 | } | |
165 | elsif( $type =~ /^\w+(?:::\w+)*$/ ){ | |
166 | $out .= " if (defined(\$init{'$name'})) {\n"; | |
167 | $out .= " if (ref \$init{'$name'} eq 'HASH')\n"; | |
168 | $out .= " { \$r->$elem = $type->new(\%{\$init{'$name'}}) } $cmt\n"; | |
169 | $out .= " elsif (UNIVERSAL::isa(\$init{'$name'}, '$type'))\n"; | |
170 | $out .= " { \$r->$elem = \$init{'$name'} } $cmt\n"; | |
171 | $out .= " else { croak 'Initializer for $name must be hash or $type reference' }\n"; | |
172 | $out .= " }\n"; | |
173 | $classes{$name} = $type; | |
174 | $got_class = 1; | |
175 | } | |
176 | else{ | |
177 | croak "'$type' is not a valid struct element type"; | |
178 | } | |
179 | $idx += 2; | |
180 | } | |
181 | $out .= " bless \$r, \$class;\n }\n"; | |
182 | ||
183 | # Create accessor methods. | |
184 | ||
185 | my( $pre, $pst, $sel ); | |
186 | $cnt = 0; | |
187 | foreach $name (@methods){ | |
188 | if ( do { no strict 'refs'; defined &{$class . "::$name"} } ) { | |
189 | warnings::warnif("function '$name' already defined, overrides struct accessor method"); | |
190 | } | |
191 | else { | |
192 | $pre = $pst = $cmt = $sel = ''; | |
193 | if( defined $refs{$name} ){ | |
194 | $pre = "\\("; | |
195 | $pst = ")"; | |
196 | $cmt = " # returns ref"; | |
197 | } | |
198 | $out .= " sub $name {$cmt\n my \$r = shift;\n"; | |
199 | if( $base_type eq 'ARRAY' ){ | |
200 | $elem = "[$cnt]"; | |
201 | ++$cnt; | |
202 | } | |
203 | elsif( $base_type eq 'HASH' ){ | |
204 | $elem = "{'${class}::$name'}"; | |
205 | } | |
206 | if( defined $arrays{$name} ){ | |
207 | $out .= " my \$i;\n"; | |
208 | $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n"; | |
209 | $out .= " if (ref(\$i) eq 'ARRAY' && !\@_) { \$r->$elem = \$i; return \$r }\n"; | |
210 | $sel = "->[\$i]"; | |
211 | } | |
212 | elsif( defined $hashes{$name} ){ | |
213 | $out .= " my \$i;\n"; | |
214 | $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n"; | |
215 | $out .= " if (ref(\$i) eq 'HASH' && !\@_) { \$r->$elem = \$i; return \$r }\n"; | |
216 | $sel = "->{\$i}"; | |
217 | } | |
218 | elsif( defined $classes{$name} ){ | |
219 | if ( $CHECK_CLASS_MEMBERSHIP ) { | |
220 | $out .= " croak '$name argument is wrong class' if \@_ && ! UNIVERSAL::isa(\$_[0], '$classes{$name}');\n"; | |
221 | } | |
222 | } | |
223 | $out .= " croak 'Too many args to $name' if \@_ > 1;\n"; | |
224 | $out .= " \@_ ? ($pre\$r->$elem$sel = shift$pst) : $pre\$r->$elem$sel$pst;\n"; | |
225 | $out .= " }\n"; | |
226 | } | |
227 | } | |
228 | $out .= "}\n1;\n"; | |
229 | ||
230 | print $out if $print; | |
231 | my $result = eval $out; | |
232 | carp $@ if $@; | |
233 | } | |
234 | ||
235 | sub _usage_error { | |
236 | confess "struct usage error"; | |
237 | } | |
238 | ||
239 | sub _subclass_error { | |
240 | croak 'struct class cannot be a subclass (@ISA not allowed)'; | |
241 | } | |
242 | ||
243 | 1; # for require | |
244 | ||
245 | ||
246 | __END__ | |
247 | ||
248 | =head1 NAME | |
249 | ||
250 | Class::Struct - declare struct-like datatypes as Perl classes | |
251 | ||
252 | =head1 SYNOPSIS | |
253 | ||
254 | use Class::Struct; | |
255 | # declare struct, based on array: | |
256 | struct( CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ]); | |
257 | # declare struct, based on hash: | |
258 | struct( CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... }); | |
259 | ||
260 | package CLASS_NAME; | |
261 | use Class::Struct; | |
262 | # declare struct, based on array, implicit class name: | |
263 | struct( ELEMENT_NAME => ELEMENT_TYPE, ... ); | |
264 | ||
265 | # Declare struct at compile time | |
266 | use Class::Struct CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ]; | |
267 | use Class::Struct CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... }; | |
268 | ||
269 | # declare struct at compile time, based on array, implicit class name: | |
270 | package CLASS_NAME; | |
271 | use Class::Struct ELEMENT_NAME => ELEMENT_TYPE, ... ; | |
272 | ||
273 | package Myobj; | |
274 | use Class::Struct; | |
275 | # declare struct with four types of elements: | |
276 | struct( s => '$', a => '@', h => '%', c => 'My_Other_Class' ); | |
277 | ||
278 | $obj = new Myobj; # constructor | |
279 | ||
280 | # scalar type accessor: | |
281 | $element_value = $obj->s; # element value | |
282 | $obj->s('new value'); # assign to element | |
283 | ||
284 | # array type accessor: | |
285 | $ary_ref = $obj->a; # reference to whole array | |
286 | $ary_element_value = $obj->a(2); # array element value | |
287 | $obj->a(2, 'new value'); # assign to array element | |
288 | ||
289 | # hash type accessor: | |
290 | $hash_ref = $obj->h; # reference to whole hash | |
291 | $hash_element_value = $obj->h('x'); # hash element value | |
292 | $obj->h('x', 'new value'); # assign to hash element | |
293 | ||
294 | # class type accessor: | |
295 | $element_value = $obj->c; # object reference | |
296 | $obj->c->method(...); # call method of object | |
297 | $obj->c(new My_Other_Class); # assign a new object | |
298 | ||
299 | =head1 DESCRIPTION | |
300 | ||
301 | C<Class::Struct> exports a single function, C<struct>. | |
302 | Given a list of element names and types, and optionally | |
303 | a class name, C<struct> creates a Perl 5 class that implements | |
304 | a "struct-like" data structure. | |
305 | ||
306 | The new class is given a constructor method, C<new>, for creating | |
307 | struct objects. | |
308 | ||
309 | Each element in the struct data has an accessor method, which is | |
310 | used to assign to the element and to fetch its value. The | |
311 | default accessor can be overridden by declaring a C<sub> of the | |
312 | same name in the package. (See Example 2.) | |
313 | ||
314 | Each element's type can be scalar, array, hash, or class. | |
315 | ||
316 | =head2 The C<struct()> function | |
317 | ||
318 | The C<struct> function has three forms of parameter-list. | |
319 | ||
320 | struct( CLASS_NAME => [ ELEMENT_LIST ]); | |
321 | struct( CLASS_NAME => { ELEMENT_LIST }); | |
322 | struct( ELEMENT_LIST ); | |
323 | ||
324 | The first and second forms explicitly identify the name of the | |
325 | class being created. The third form assumes the current package | |
326 | name as the class name. | |
327 | ||
328 | An object of a class created by the first and third forms is | |
329 | based on an array, whereas an object of a class created by the | |
330 | second form is based on a hash. The array-based forms will be | |
331 | somewhat faster and smaller; the hash-based forms are more | |
332 | flexible. | |
333 | ||
334 | The class created by C<struct> must not be a subclass of another | |
335 | class other than C<UNIVERSAL>. | |
336 | ||
337 | It can, however, be used as a superclass for other classes. To facilitate | |
338 | this, the generated constructor method uses a two-argument blessing. | |
339 | Furthermore, if the class is hash-based, the key of each element is | |
340 | prefixed with the class name (see I<Perl Cookbook>, Recipe 13.12). | |
341 | ||
342 | A function named C<new> must not be explicitly defined in a class | |
343 | created by C<struct>. | |
344 | ||
345 | The I<ELEMENT_LIST> has the form | |
346 | ||
347 | NAME => TYPE, ... | |
348 | ||
349 | Each name-type pair declares one element of the struct. Each | |
350 | element name will be defined as an accessor method unless a | |
351 | method by that name is explicitly defined; in the latter case, a | |
352 | warning is issued if the warning flag (B<-w>) is set. | |
353 | ||
354 | =head2 Class Creation at Compile Time | |
355 | ||
356 | C<Class::Struct> can create your class at compile time. The main reason | |
357 | for doing this is obvious, so your class acts like every other class in | |
358 | Perl. Creating your class at compile time will make the order of events | |
359 | similar to using any other class ( or Perl module ). | |
360 | ||
361 | There is no significant speed gain between compile time and run time | |
362 | class creation, there is just a new, more standard order of events. | |
363 | ||
364 | =head2 Element Types and Accessor Methods | |
365 | ||
366 | The four element types -- scalar, array, hash, and class -- are | |
367 | represented by strings -- C<'$'>, C<'@'>, C<'%'>, and a class name -- | |
368 | optionally preceded by a C<'*'>. | |
369 | ||
370 | The accessor method provided by C<struct> for an element depends | |
371 | on the declared type of the element. | |
372 | ||
373 | =over 4 | |
374 | ||
375 | =item Scalar (C<'$'> or C<'*$'>) | |
376 | ||
377 | The element is a scalar, and by default is initialized to C<undef> | |
378 | (but see L<Initializing with new>). | |
379 | ||
380 | The accessor's argument, if any, is assigned to the element. | |
381 | ||
382 | If the element type is C<'$'>, the value of the element (after | |
383 | assignment) is returned. If the element type is C<'*$'>, a reference | |
384 | to the element is returned. | |
385 | ||
386 | =item Array (C<'@'> or C<'*@'>) | |
387 | ||
388 | The element is an array, initialized by default to C<()>. | |
389 | ||
390 | With no argument, the accessor returns a reference to the | |
391 | element's whole array (whether or not the element was | |
392 | specified as C<'@'> or C<'*@'>). | |
393 | ||
394 | With one or two arguments, the first argument is an index | |
395 | specifying one element of the array; the second argument, if | |
396 | present, is assigned to the array element. If the element type | |
397 | is C<'@'>, the accessor returns the array element value. If the | |
398 | element type is C<'*@'>, a reference to the array element is | |
399 | returned. | |
400 | ||
401 | As a special case, when the accessor is called with an array reference | |
402 | as the sole argument, this causes an assignment of the whole array element. | |
403 | The object reference is returned. | |
404 | ||
405 | =item Hash (C<'%'> or C<'*%'>) | |
406 | ||
407 | The element is a hash, initialized by default to C<()>. | |
408 | ||
409 | With no argument, the accessor returns a reference to the | |
410 | element's whole hash (whether or not the element was | |
411 | specified as C<'%'> or C<'*%'>). | |
412 | ||
413 | With one or two arguments, the first argument is a key specifying | |
414 | one element of the hash; the second argument, if present, is | |
415 | assigned to the hash element. If the element type is C<'%'>, the | |
416 | accessor returns the hash element value. If the element type is | |
417 | C<'*%'>, a reference to the hash element is returned. | |
418 | ||
419 | As a special case, when the accessor is called with a hash reference | |
420 | as the sole argument, this causes an assignment of the whole hash element. | |
421 | The object reference is returned. | |
422 | ||
423 | =item Class (C<'Class_Name'> or C<'*Class_Name'>) | |
424 | ||
425 | The element's value must be a reference blessed to the named | |
426 | class or to one of its subclasses. The element is not initialized | |
427 | by default. | |
428 | ||
429 | The accessor's argument, if any, is assigned to the element. The | |
430 | accessor will C<croak> if this is not an appropriate object | |
431 | reference. | |
432 | ||
433 | If the element type does not start with a C<'*'>, the accessor | |
434 | returns the element value (after assignment). If the element type | |
435 | starts with a C<'*'>, a reference to the element itself is returned. | |
436 | ||
437 | =back | |
438 | ||
439 | =head2 Initializing with C<new> | |
440 | ||
441 | C<struct> always creates a constructor called C<new>. That constructor | |
442 | may take a list of initializers for the various elements of the new | |
443 | struct. | |
444 | ||
445 | Each initializer is a pair of values: I<element name>C< =E<gt> >I<value>. | |
446 | The initializer value for a scalar element is just a scalar value. The | |
447 | initializer for an array element is an array reference. The initializer | |
448 | for a hash is a hash reference. | |
449 | ||
450 | The initializer for a class element is an object of the corresponding class, | |
451 | or of one of it's subclasses, or a reference to a hash containing named | |
452 | arguments to be passed to the element's constructor. | |
453 | ||
454 | See Example 3 below for an example of initialization. | |
455 | ||
456 | =head1 EXAMPLES | |
457 | ||
458 | =over 4 | |
459 | ||
460 | =item Example 1 | |
461 | ||
462 | Giving a struct element a class type that is also a struct is how | |
463 | structs are nested. Here, C<Timeval> represents a time (seconds and | |
464 | microseconds), and C<Rusage> has two elements, each of which is of | |
465 | type C<Timeval>. | |
466 | ||
467 | use Class::Struct; | |
468 | ||
469 | struct( Rusage => { | |
470 | ru_utime => 'Timeval', # user time used | |
471 | ru_stime => 'Timeval', # system time used | |
472 | }); | |
473 | ||
474 | struct( Timeval => [ | |
475 | tv_secs => '$', # seconds | |
476 | tv_usecs => '$', # microseconds | |
477 | ]); | |
478 | ||
479 | # create an object: | |
480 | my $t = Rusage->new(ru_utime=>Timeval->new(), ru_stime=>Timeval->new()); | |
481 | ||
482 | # $t->ru_utime and $t->ru_stime are objects of type Timeval. | |
483 | # set $t->ru_utime to 100.0 sec and $t->ru_stime to 5.0 sec. | |
484 | $t->ru_utime->tv_secs(100); | |
485 | $t->ru_utime->tv_usecs(0); | |
486 | $t->ru_stime->tv_secs(5); | |
487 | $t->ru_stime->tv_usecs(0); | |
488 | ||
489 | =item Example 2 | |
490 | ||
491 | An accessor function can be redefined in order to provide | |
492 | additional checking of values, etc. Here, we want the C<count> | |
493 | element always to be nonnegative, so we redefine the C<count> | |
494 | accessor accordingly. | |
495 | ||
496 | package MyObj; | |
497 | use Class::Struct; | |
498 | ||
499 | # declare the struct | |
500 | struct ( 'MyObj', { count => '$', stuff => '%' } ); | |
501 | ||
502 | # override the default accessor method for 'count' | |
503 | sub count { | |
504 | my $self = shift; | |
505 | if ( @_ ) { | |
506 | die 'count must be nonnegative' if $_[0] < 0; | |
507 | $self->{'MyObj::count'} = shift; | |
508 | warn "Too many args to count" if @_; | |
509 | } | |
510 | return $self->{'MyObj::count'}; | |
511 | } | |
512 | ||
513 | package main; | |
514 | $x = new MyObj; | |
515 | print "\$x->count(5) = ", $x->count(5), "\n"; | |
516 | # prints '$x->count(5) = 5' | |
517 | ||
518 | print "\$x->count = ", $x->count, "\n"; | |
519 | # prints '$x->count = 5' | |
520 | ||
521 | print "\$x->count(-5) = ", $x->count(-5), "\n"; | |
522 | # dies due to negative argument! | |
523 | ||
524 | =item Example 3 | |
525 | ||
526 | The constructor of a generated class can be passed a list | |
527 | of I<element>=>I<value> pairs, with which to initialize the struct. | |
528 | If no initializer is specified for a particular element, its default | |
529 | initialization is performed instead. Initializers for non-existent | |
530 | elements are silently ignored. | |
531 | ||
532 | Note that the initializer for a nested class may be specified as | |
533 | an object of that class, or as a reference to a hash of initializers | |
534 | that are passed on to the nested struct's constructor. | |
535 | ||
536 | use Class::Struct; | |
537 | ||
538 | struct Breed => | |
539 | { | |
540 | name => '$', | |
541 | cross => '$', | |
542 | }; | |
543 | ||
544 | struct Cat => | |
545 | [ | |
546 | name => '$', | |
547 | kittens => '@', | |
548 | markings => '%', | |
549 | breed => 'Breed', | |
550 | ]; | |
551 | ||
552 | ||
553 | my $cat = Cat->new( name => 'Socks', | |
554 | kittens => ['Monica', 'Kenneth'], | |
555 | markings => { socks=>1, blaze=>"white" }, | |
556 | breed => Breed->new(name=>'short-hair', cross=>1), | |
557 | or: breed => {name=>'short-hair', cross=>1}, | |
558 | ); | |
559 | ||
560 | print "Once a cat called ", $cat->name, "\n"; | |
561 | print "(which was a ", $cat->breed->name, ")\n"; | |
562 | print "had two kittens: ", join(' and ', @{$cat->kittens}), "\n"; | |
563 | ||
564 | =back | |
565 | ||
566 | =head1 Author and Modification History | |
567 | ||
568 | Modified by Damian Conway, 2001-09-10, v0.62. | |
569 | ||
570 | Modified implicit construction of nested objects. | |
571 | Now will also take an object ref instead of requiring a hash ref. | |
572 | Also default initializes nested object attributes to undef, rather | |
573 | than calling object constructor without args | |
574 | Original over-helpfulness was fraught with problems: | |
575 | * the class's constructor might not be called 'new' | |
576 | * the class might not have a hash-like-arguments constructor | |
577 | * the class might not have a no-argument constructor | |
578 | * "recursive" data structures didn't work well: | |
579 | package Person; | |
580 | struct { mother => 'Person', father => 'Person'}; | |
581 | ||
582 | ||
583 | Modified by Casey West, 2000-11-08, v0.59. | |
584 | ||
585 | Added the ability for compile time class creation. | |
586 | ||
587 | Modified by Damian Conway, 1999-03-05, v0.58. | |
588 | ||
589 | Added handling of hash-like arg list to class ctor. | |
590 | ||
591 | Changed to two-argument blessing in ctor to support | |
592 | derivation from created classes. | |
593 | ||
594 | Added classname prefixes to keys in hash-based classes | |
595 | (refer to "Perl Cookbook", Recipe 13.12 for rationale). | |
596 | ||
597 | Corrected behaviour of accessors for '*@' and '*%' struct | |
598 | elements. Package now implements documented behaviour when | |
599 | returning a reference to an entire hash or array element. | |
600 | Previously these were returned as a reference to a reference | |
601 | to the element. | |
602 | ||
603 | Renamed to C<Class::Struct> and modified by Jim Miner, 1997-04-02. | |
604 | ||
605 | members() function removed. | |
606 | Documentation corrected and extended. | |
607 | Use of struct() in a subclass prohibited. | |
608 | User definition of accessor allowed. | |
609 | Treatment of '*' in element types corrected. | |
610 | Treatment of classes as element types corrected. | |
611 | Class name to struct() made optional. | |
612 | Diagnostic checks added. | |
613 | ||
614 | Originally C<Class::Template> by Dean Roehrich. | |
615 | ||
616 | # Template.pm --- struct/member template builder | |
617 | # 12mar95 | |
618 | # Dean Roehrich | |
619 | # | |
620 | # changes/bugs fixed since 28nov94 version: | |
621 | # - podified | |
622 | # changes/bugs fixed since 21nov94 version: | |
623 | # - Fixed examples. | |
624 | # changes/bugs fixed since 02sep94 version: | |
625 | # - Moved to Class::Template. | |
626 | # changes/bugs fixed since 20feb94 version: | |
627 | # - Updated to be a more proper module. | |
628 | # - Added "use strict". | |
629 | # - Bug in build_methods, was using @var when @$var needed. | |
630 | # - Now using my() rather than local(). | |
631 | # | |
632 | # Uses perl5 classes to create nested data types. | |
633 | # This is offered as one implementation of Tom Christiansen's "structs.pl" | |
634 | # idea. | |
635 | ||
636 | =cut |