Commit | Line | Data |
8cc95fdb |
1 | package Class::Struct; |
2 | |
3 | ## See POD after __END__ |
4 | |
17f410f9 |
5 | use 5.005_64; |
8cc95fdb |
6 | |
7 | use strict; |
d3a7d8c7 |
8 | use warnings::register; |
17f410f9 |
9 | our(@ISA, @EXPORT, $VERSION); |
8cc95fdb |
10 | |
11 | use Carp; |
12 | |
13 | require Exporter; |
14 | @ISA = qw(Exporter); |
15 | @EXPORT = qw(struct); |
16 | |
ab6e6725 |
17 | $VERSION = '0.59'; |
430530ea |
18 | |
8cc95fdb |
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 | |
f740b751 |
46 | sub FETCHSIZE { |
47 | my $self = shift; |
48 | return scalar(@$self); |
49 | } |
50 | |
8cc95fdb |
51 | sub DESTROY { } |
52 | } |
53 | |
ab6e6725 |
54 | sub import { |
55 | my $self = shift; |
56 | |
57 | if ( @_ ) { |
58 | &struct; |
59 | } else { |
60 | $self->export_to_level( 1, $self, @EXPORT ); |
61 | } |
62 | } |
63 | |
8cc95fdb |
64 | sub struct { |
65 | |
66 | # Determine parameter list structure, one of: |
67 | # struct( class => [ element-list ]) |
68 | # struct( class => { element-list }) |
69 | # struct( element-list ) |
70 | # Latter form assumes current package name as struct name. |
71 | |
72 | my ($class, @decls); |
73 | my $base_type = ref $_[1]; |
74 | if ( $base_type eq 'HASH' ) { |
75 | $class = shift; |
76 | @decls = %{shift()}; |
77 | _usage_error() if @_; |
78 | } |
79 | elsif ( $base_type eq 'ARRAY' ) { |
80 | $class = shift; |
81 | @decls = @{shift()}; |
82 | _usage_error() if @_; |
83 | } |
84 | else { |
85 | $base_type = 'ARRAY'; |
86 | $class = (caller())[0]; |
87 | @decls = @_; |
88 | } |
89 | _usage_error() if @decls % 2 == 1; |
90 | |
91 | # Ensure we are not, and will not be, a subclass. |
92 | |
93 | my $isa = do { |
94 | no strict 'refs'; |
95 | \@{$class . '::ISA'}; |
96 | }; |
97 | _subclass_error() if @$isa; |
98 | tie @$isa, 'Class::Struct::Tie_ISA'; |
99 | |
100 | # Create constructor. |
101 | |
102 | croak "function 'new' already defined in package $class" |
103 | if do { no strict 'refs'; defined &{$class . "::new"} }; |
104 | |
105 | my @methods = (); |
106 | my %refs = (); |
107 | my %arrays = (); |
108 | my %hashes = (); |
109 | my %classes = (); |
110 | my $got_class = 0; |
111 | my $out = ''; |
112 | |
113 | $out = "{\n package $class;\n use Carp;\n sub new {\n"; |
430530ea |
114 | $out .= " my (\$class, \%init) = \@_;\n"; |
f01e5ef6 |
115 | $out .= " \$class = __PACKAGE__ unless \@_;\n"; |
8cc95fdb |
116 | |
117 | my $cnt = 0; |
118 | my $idx = 0; |
119 | my( $cmt, $name, $type, $elem ); |
120 | |
121 | if( $base_type eq 'HASH' ){ |
122 | $out .= " my(\$r) = {};\n"; |
123 | $cmt = ''; |
124 | } |
125 | elsif( $base_type eq 'ARRAY' ){ |
126 | $out .= " my(\$r) = [];\n"; |
127 | } |
128 | while( $idx < @decls ){ |
129 | $name = $decls[$idx]; |
130 | $type = $decls[$idx+1]; |
131 | push( @methods, $name ); |
132 | if( $base_type eq 'HASH' ){ |
430530ea |
133 | $elem = "{'${class}::$name'}"; |
8cc95fdb |
134 | } |
135 | elsif( $base_type eq 'ARRAY' ){ |
136 | $elem = "[$cnt]"; |
137 | ++$cnt; |
138 | $cmt = " # $name"; |
139 | } |
140 | if( $type =~ /^\*(.)/ ){ |
141 | $refs{$name}++; |
142 | $type = $1; |
143 | } |
430530ea |
144 | my $init = "defined(\$init{'$name'}) ? \$init{'$name'} :"; |
8cc95fdb |
145 | if( $type eq '@' ){ |
430530ea |
146 | $out .= " croak 'Initializer for $name must be array reference'\n"; |
147 | $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'ARRAY';\n"; |
148 | $out .= " \$r->$elem = $init [];$cmt\n"; |
8cc95fdb |
149 | $arrays{$name}++; |
150 | } |
151 | elsif( $type eq '%' ){ |
430530ea |
152 | $out .= " croak 'Initializer for $name must be hash reference'\n"; |
153 | $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'HASH';\n"; |
154 | $out .= " \$r->$elem = $init {};$cmt\n"; |
8cc95fdb |
155 | $hashes{$name}++; |
156 | } |
157 | elsif ( $type eq '$') { |
430530ea |
158 | $out .= " \$r->$elem = $init undef;$cmt\n"; |
8cc95fdb |
159 | } |
160 | elsif( $type =~ /^\w+(?:::\w+)*$/ ){ |
430530ea |
161 | $init = "defined(\$init{'$name'}) ? \%{\$init{'$name'}} : ()"; |
162 | $out .= " croak 'Initializer for $name must be hash reference'\n"; |
163 | $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'HASH';\n"; |
164 | $out .= " \$r->$elem = '${type}'->new($init);$cmt\n"; |
8cc95fdb |
165 | $classes{$name} = $type; |
166 | $got_class = 1; |
167 | } |
168 | else{ |
169 | croak "'$type' is not a valid struct element type"; |
170 | } |
171 | $idx += 2; |
172 | } |
430530ea |
173 | $out .= " bless \$r, \$class;\n }\n"; |
8cc95fdb |
174 | |
175 | # Create accessor methods. |
176 | |
8cc95fdb |
177 | my( $pre, $pst, $sel ); |
178 | $cnt = 0; |
179 | foreach $name (@methods){ |
180 | if ( do { no strict 'refs'; defined &{$class . "::$name"} } ) { |
7e6d00f8 |
181 | warnings::warnif("function '$name' already defined, overrides struct accessor method"); |
8cc95fdb |
182 | } |
183 | else { |
184 | $pre = $pst = $cmt = $sel = ''; |
185 | if( defined $refs{$name} ){ |
186 | $pre = "\\("; |
187 | $pst = ")"; |
188 | $cmt = " # returns ref"; |
189 | } |
190 | $out .= " sub $name {$cmt\n my \$r = shift;\n"; |
191 | if( $base_type eq 'ARRAY' ){ |
192 | $elem = "[$cnt]"; |
193 | ++$cnt; |
194 | } |
195 | elsif( $base_type eq 'HASH' ){ |
430530ea |
196 | $elem = "{'${class}::$name'}"; |
8cc95fdb |
197 | } |
198 | if( defined $arrays{$name} ){ |
199 | $out .= " my \$i;\n"; |
430530ea |
200 | $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n"; |
8cc95fdb |
201 | $sel = "->[\$i]"; |
202 | } |
203 | elsif( defined $hashes{$name} ){ |
204 | $out .= " my \$i;\n"; |
430530ea |
205 | $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n"; |
8cc95fdb |
206 | $sel = "->{\$i}"; |
207 | } |
208 | elsif( defined $classes{$name} ){ |
209 | if ( $CHECK_CLASS_MEMBERSHIP ) { |
20408e3c |
210 | $out .= " croak '$name argument is wrong class' if \@_ && ! UNIVERSAL::isa(\$_[0], '$classes{$name}');\n"; |
8cc95fdb |
211 | } |
212 | } |
213 | $out .= " croak 'Too many args to $name' if \@_ > 1;\n"; |
214 | $out .= " \@_ ? ($pre\$r->$elem$sel = shift$pst) : $pre\$r->$elem$sel$pst;\n"; |
215 | $out .= " }\n"; |
216 | } |
217 | } |
218 | $out .= "}\n1;\n"; |
219 | |
220 | print $out if $print; |
221 | my $result = eval $out; |
222 | carp $@ if $@; |
223 | } |
224 | |
225 | sub _usage_error { |
226 | confess "struct usage error"; |
227 | } |
228 | |
229 | sub _subclass_error { |
230 | croak 'struct class cannot be a subclass (@ISA not allowed)'; |
231 | } |
232 | |
233 | 1; # for require |
234 | |
235 | |
236 | __END__ |
237 | |
238 | =head1 NAME |
239 | |
240 | Class::Struct - declare struct-like datatypes as Perl classes |
241 | |
242 | =head1 SYNOPSIS |
243 | |
244 | use Class::Struct; |
245 | # declare struct, based on array: |
246 | struct( CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ]); |
247 | # declare struct, based on hash: |
248 | struct( CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... }); |
249 | |
250 | package CLASS_NAME; |
251 | use Class::Struct; |
252 | # declare struct, based on array, implicit class name: |
253 | struct( ELEMENT_NAME => ELEMENT_TYPE, ... ); |
254 | |
ab6e6725 |
255 | # Declare struct at compile time |
256 | use Class::Struct CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ]; |
257 | use Class::Struct CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... }; |
258 | |
8cc95fdb |
259 | |
260 | package Myobj; |
261 | use Class::Struct; |
262 | # declare struct with four types of elements: |
263 | struct( s => '$', a => '@', h => '%', c => 'My_Other_Class' ); |
264 | |
265 | $obj = new Myobj; # constructor |
266 | |
267 | # scalar type accessor: |
268 | $element_value = $obj->s; # element value |
269 | $obj->s('new value'); # assign to element |
270 | |
271 | # array type accessor: |
272 | $ary_ref = $obj->a; # reference to whole array |
273 | $ary_element_value = $obj->a(2); # array element value |
274 | $obj->a(2, 'new value'); # assign to array element |
275 | |
276 | # hash type accessor: |
277 | $hash_ref = $obj->h; # reference to whole hash |
278 | $hash_element_value = $obj->h('x'); # hash element value |
279 | $obj->h('x', 'new value'); # assign to hash element |
280 | |
281 | # class type accessor: |
282 | $element_value = $obj->c; # object reference |
283 | $obj->c->method(...); # call method of object |
284 | $obj->c(new My_Other_Class); # assign a new object |
285 | |
286 | |
287 | =head1 DESCRIPTION |
288 | |
289 | C<Class::Struct> exports a single function, C<struct>. |
290 | Given a list of element names and types, and optionally |
291 | a class name, C<struct> creates a Perl 5 class that implements |
292 | a "struct-like" data structure. |
293 | |
294 | The new class is given a constructor method, C<new>, for creating |
295 | struct objects. |
296 | |
297 | Each element in the struct data has an accessor method, which is |
298 | used to assign to the element and to fetch its value. The |
299 | default accessor can be overridden by declaring a C<sub> of the |
300 | same name in the package. (See Example 2.) |
301 | |
302 | Each element's type can be scalar, array, hash, or class. |
303 | |
304 | |
305 | =head2 The C<struct()> function |
306 | |
307 | The C<struct> function has three forms of parameter-list. |
308 | |
309 | struct( CLASS_NAME => [ ELEMENT_LIST ]); |
310 | struct( CLASS_NAME => { ELEMENT_LIST }); |
311 | struct( ELEMENT_LIST ); |
312 | |
313 | The first and second forms explicitly identify the name of the |
314 | class being created. The third form assumes the current package |
315 | name as the class name. |
316 | |
317 | An object of a class created by the first and third forms is |
318 | based on an array, whereas an object of a class created by the |
319 | second form is based on a hash. The array-based forms will be |
320 | somewhat faster and smaller; the hash-based forms are more |
321 | flexible. |
322 | |
323 | The class created by C<struct> must not be a subclass of another |
324 | class other than C<UNIVERSAL>. |
325 | |
430530ea |
326 | It can, however, be used as a superclass for other classes. To facilitate |
327 | this, the generated constructor method uses a two-argument blessing. |
328 | Furthermore, if the class is hash-based, the key of each element is |
329 | prefixed with the class name (see I<Perl Cookbook>, Recipe 13.12). |
330 | |
8cc95fdb |
331 | A function named C<new> must not be explicitly defined in a class |
332 | created by C<struct>. |
333 | |
334 | The I<ELEMENT_LIST> has the form |
335 | |
336 | NAME => TYPE, ... |
337 | |
338 | Each name-type pair declares one element of the struct. Each |
339 | element name will be defined as an accessor method unless a |
340 | method by that name is explicitly defined; in the latter case, a |
103ff8e3 |
341 | warning is issued if the warning flag (B<-w>) is set. |
8cc95fdb |
342 | |
ab6e6725 |
343 | =head2 Class Creation at Compile Time |
344 | |
345 | C<Class::Struct> can create your class at compile time. The main reason |
346 | for doing this is obvious, so your class acts like every other class in |
347 | Perl. Creating your class at compile time will make the order of events |
348 | similar to using any other class ( or Perl module ). |
349 | |
350 | There is no significant speed gain between compile time and run time |
351 | class creation, there is just a new, more standard order of events. |
8cc95fdb |
352 | |
353 | =head2 Element Types and Accessor Methods |
354 | |
355 | The four element types -- scalar, array, hash, and class -- are |
356 | represented by strings -- C<'$'>, C<'@'>, C<'%'>, and a class name -- |
357 | optionally preceded by a C<'*'>. |
358 | |
359 | The accessor method provided by C<struct> for an element depends |
360 | on the declared type of the element. |
361 | |
362 | =over |
363 | |
364 | =item Scalar (C<'$'> or C<'*$'>) |
365 | |
430530ea |
366 | The element is a scalar, and by default is initialized to C<undef> |
367 | (but see L<Initializing with new>). |
8cc95fdb |
368 | |
369 | The accessor's argument, if any, is assigned to the element. |
370 | |
371 | If the element type is C<'$'>, the value of the element (after |
372 | assignment) is returned. If the element type is C<'*$'>, a reference |
373 | to the element is returned. |
374 | |
375 | =item Array (C<'@'> or C<'*@'>) |
376 | |
430530ea |
377 | The element is an array, initialized by default to C<()>. |
8cc95fdb |
378 | |
379 | With no argument, the accessor returns a reference to the |
430530ea |
380 | element's whole array (whether or not the element was |
58231d39 |
381 | specified as C<'@'> or C<'*@'>). |
8cc95fdb |
382 | |
383 | With one or two arguments, the first argument is an index |
384 | specifying one element of the array; the second argument, if |
385 | present, is assigned to the array element. If the element type |
386 | is C<'@'>, the accessor returns the array element value. If the |
387 | element type is C<'*@'>, a reference to the array element is |
388 | returned. |
389 | |
390 | =item Hash (C<'%'> or C<'*%'>) |
391 | |
430530ea |
392 | The element is a hash, initialized by default to C<()>. |
8cc95fdb |
393 | |
394 | With no argument, the accessor returns a reference to the |
430530ea |
395 | element's whole hash (whether or not the element was |
58231d39 |
396 | specified as C<'%'> or C<'*%'>). |
8cc95fdb |
397 | |
398 | With one or two arguments, the first argument is a key specifying |
399 | one element of the hash; the second argument, if present, is |
400 | assigned to the hash element. If the element type is C<'%'>, the |
401 | accessor returns the hash element value. If the element type is |
402 | C<'*%'>, a reference to the hash element is returned. |
403 | |
404 | =item Class (C<'Class_Name'> or C<'*Class_Name'>) |
405 | |
406 | The element's value must be a reference blessed to the named |
407 | class or to one of its subclasses. The element is initialized to |
408 | the result of calling the C<new> constructor of the named class. |
409 | |
410 | The accessor's argument, if any, is assigned to the element. The |
411 | accessor will C<croak> if this is not an appropriate object |
412 | reference. |
413 | |
414 | If the element type does not start with a C<'*'>, the accessor |
415 | returns the element value (after assignment). If the element type |
416 | starts with a C<'*'>, a reference to the element itself is returned. |
417 | |
418 | =back |
419 | |
430530ea |
420 | =head2 Initializing with C<new> |
421 | |
422 | C<struct> always creates a constructor called C<new>. That constructor |
423 | may take a list of initializers for the various elements of the new |
424 | struct. |
425 | |
426 | Each initializer is a pair of values: I<element name>C< =E<gt> >I<value>. |
427 | The initializer value for a scalar element is just a scalar value. The |
428 | initializer for an array element is an array reference. The initializer |
429 | for a hash is a hash reference. |
430 | |
431 | The initializer for a class element is also a hash reference, and the |
432 | contents of that hash are passed to the element's own constructor. |
433 | |
434 | See Example 3 below for an example of initialization. |
435 | |
436 | |
8cc95fdb |
437 | =head1 EXAMPLES |
438 | |
439 | =over |
440 | |
441 | =item Example 1 |
442 | |
443 | Giving a struct element a class type that is also a struct is how |
444 | structs are nested. Here, C<timeval> represents a time (seconds and |
445 | microseconds), and C<rusage> has two elements, each of which is of |
446 | type C<timeval>. |
447 | |
448 | use Class::Struct; |
449 | |
450 | struct( rusage => { |
451 | ru_utime => timeval, # seconds |
452 | ru_stime => timeval, # microseconds |
453 | }); |
454 | |
455 | struct( timeval => [ |
456 | tv_secs => '$', |
457 | tv_usecs => '$', |
458 | ]); |
459 | |
460 | # create an object: |
461 | my $t = new rusage; |
8cc95fdb |
462 | |
430530ea |
463 | # $t->ru_utime and $t->ru_stime are objects of type timeval. |
8cc95fdb |
464 | # set $t->ru_utime to 100.0 sec and $t->ru_stime to 5.0 sec. |
465 | $t->ru_utime->tv_secs(100); |
466 | $t->ru_utime->tv_usecs(0); |
467 | $t->ru_stime->tv_secs(5); |
468 | $t->ru_stime->tv_usecs(0); |
469 | |
470 | |
471 | =item Example 2 |
472 | |
473 | An accessor function can be redefined in order to provide |
474 | additional checking of values, etc. Here, we want the C<count> |
475 | element always to be nonnegative, so we redefine the C<count> |
476 | accessor accordingly. |
477 | |
478 | package MyObj; |
479 | use Class::Struct; |
480 | |
430530ea |
481 | # declare the struct |
8cc95fdb |
482 | struct ( 'MyObj', { count => '$', stuff => '%' } ); |
483 | |
430530ea |
484 | # override the default accessor method for 'count' |
8cc95fdb |
485 | sub count { |
486 | my $self = shift; |
487 | if ( @_ ) { |
488 | die 'count must be nonnegative' if $_[0] < 0; |
489 | $self->{'count'} = shift; |
490 | warn "Too many args to count" if @_; |
491 | } |
492 | return $self->{'count'}; |
493 | } |
494 | |
495 | package main; |
496 | $x = new MyObj; |
497 | print "\$x->count(5) = ", $x->count(5), "\n"; |
498 | # prints '$x->count(5) = 5' |
499 | |
500 | print "\$x->count = ", $x->count, "\n"; |
501 | # prints '$x->count = 5' |
502 | |
503 | print "\$x->count(-5) = ", $x->count(-5), "\n"; |
504 | # dies due to negative argument! |
505 | |
430530ea |
506 | =item Example 3 |
507 | |
508 | The constructor of a generated class can be passed a list |
509 | of I<element>=>I<value> pairs, with which to initialize the struct. |
510 | If no initializer is specified for a particular element, its default |
511 | initialization is performed instead. Initializers for non-existent |
512 | elements are silently ignored. |
513 | |
514 | Note that the initializer for a nested struct is specified |
515 | as an anonymous hash of initializers, which is passed on to the nested |
516 | struct's constructor. |
517 | |
518 | |
519 | use Class::Struct; |
520 | |
521 | struct Breed => |
522 | { |
523 | name => '$', |
524 | cross => '$', |
525 | }; |
526 | |
527 | struct Cat => |
528 | [ |
529 | name => '$', |
530 | kittens => '@', |
531 | markings => '%', |
532 | breed => 'Breed', |
533 | ]; |
534 | |
535 | |
536 | my $cat = Cat->new( name => 'Socks', |
537 | kittens => ['Monica', 'Kenneth'], |
538 | markings => { socks=>1, blaze=>"white" }, |
539 | breed => { name=>'short-hair', cross=>1 }, |
540 | ); |
541 | |
542 | print "Once a cat called ", $cat->name, "\n"; |
543 | print "(which was a ", $cat->breed->name, ")\n"; |
544 | print "had two kittens: ", join(' and ', @{$cat->kittens}), "\n"; |
545 | |
a45bd81d |
546 | =back |
8cc95fdb |
547 | |
548 | =head1 Author and Modification History |
549 | |
550 | |
ab6e6725 |
551 | Modified by Casey Tweten, 2000-11-08, v0.59. |
552 | |
553 | Added the ability for compile time class creation. |
554 | |
430530ea |
555 | Modified by Damian Conway, 1999-03-05, v0.58. |
556 | |
557 | Added handling of hash-like arg list to class ctor. |
558 | |
559 | Changed to two-argument blessing in ctor to support |
560 | derivation from created classes. |
561 | |
562 | Added classname prefixes to keys in hash-based classes |
563 | (refer to "Perl Cookbook", Recipe 13.12 for rationale). |
564 | |
565 | Corrected behaviour of accessors for '*@' and '*%' struct |
566 | elements. Package now implements documented behaviour when |
567 | returning a reference to an entire hash or array element. |
568 | Previously these were returned as a reference to a reference |
569 | to the element. |
570 | |
571 | |
8cc95fdb |
572 | Renamed to C<Class::Struct> and modified by Jim Miner, 1997-04-02. |
573 | |
574 | members() function removed. |
575 | Documentation corrected and extended. |
576 | Use of struct() in a subclass prohibited. |
577 | User definition of accessor allowed. |
578 | Treatment of '*' in element types corrected. |
579 | Treatment of classes as element types corrected. |
580 | Class name to struct() made optional. |
581 | Diagnostic checks added. |
582 | |
583 | |
584 | Originally C<Class::Template> by Dean Roehrich. |
585 | |
586 | # Template.pm --- struct/member template builder |
587 | # 12mar95 |
588 | # Dean Roehrich |
589 | # |
590 | # changes/bugs fixed since 28nov94 version: |
591 | # - podified |
592 | # changes/bugs fixed since 21nov94 version: |
593 | # - Fixed examples. |
594 | # changes/bugs fixed since 02sep94 version: |
595 | # - Moved to Class::Template. |
596 | # changes/bugs fixed since 20feb94 version: |
597 | # - Updated to be a more proper module. |
598 | # - Added "use strict". |
599 | # - Bug in build_methods, was using @var when @$var needed. |
600 | # - Now using my() rather than local(). |
601 | # |
602 | # Uses perl5 classes to create nested data types. |
603 | # This is offered as one implementation of Tom Christiansen's "structs.pl" |
604 | # idea. |
605 | |
606 | =cut |