File | /usr/local/lib/perl5/site_perl/5.10.1/darwin-2level/Variable/Magic.pm |
Statements Executed | 37 |
Statement Execution Time | 819µs |
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1 | 1 | 1 | 24µs | 38µs | wizard | Variable::Magic::
4 | 1 | 2 | 23µs | 29µs | cast (xsub) | Variable::Magic::
1 | 1 | 1 | 22µs | 22µs | BEGIN@3 | Variable::Magic::
1 | 1 | 2 | 14µs | 14µs | _wizard (xsub) | Variable::Magic::
1 | 1 | 1 | 10µs | 287µs | BEGIN@204 | Variable::Magic::
1 | 1 | 1 | 8µs | 51µs | BEGIN@560 | Variable::Magic::
1 | 1 | 1 | 8µs | 40µs | BEGIN@8 | Variable::Magic::
1 | 1 | 1 | 7µs | 9µs | BEGIN@5 | Variable::Magic::
1 | 1 | 1 | 7µs | 15µs | BEGIN@6 | Variable::Magic::
4 | 1 | 2 | 4µs | 4µs | getdata (xsub) | Variable::Magic::
1 | 1 | 1 | 3µs | 3µs | BEGIN@21 | Variable::Magic::
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1 | package Variable::Magic; | ||||
2 | |||||
3 | 3 | 32µs | 1 | 22µs | # spent 22µs within Variable::Magic::BEGIN@3 which was called
# once (22µs+0s) by B::Hooks::EndOfScope::BEGIN@7 at line 3 # spent 22µs making 1 call to Variable::Magic::BEGIN@3 |
4 | |||||
5 | 3 | 17µs | 2 | 12µs | # spent 9µs (7+3) within Variable::Magic::BEGIN@5 which was called
# once (7µs+3µs) by B::Hooks::EndOfScope::BEGIN@7 at line 5 # spent 9µs making 1 call to Variable::Magic::BEGIN@5
# spent 2µs making 1 call to strict::import |
6 | 3 | 20µs | 2 | 24µs | # spent 15µs (7+8) within Variable::Magic::BEGIN@6 which was called
# once (7µs+8µs) by B::Hooks::EndOfScope::BEGIN@7 at line 6 # spent 15µs making 1 call to Variable::Magic::BEGIN@6
# spent 8µs making 1 call to warnings::import |
7 | |||||
8 | 3 | 35µs | 2 | 72µs | # spent 40µs (8+32) within Variable::Magic::BEGIN@8 which was called
# once (8µs+32µs) by B::Hooks::EndOfScope::BEGIN@7 at line 8 # spent 40µs making 1 call to Variable::Magic::BEGIN@8
# spent 32µs making 1 call to Exporter::import |
9 | |||||
10 | =head1 NAME | ||||
11 | |||||
12 | Variable::Magic - Associate user-defined magic to variables from Perl. | ||||
13 | |||||
14 | =head1 VERSION | ||||
15 | |||||
16 | Version 0.39 | ||||
17 | |||||
18 | =cut | ||||
19 | |||||
20 | 1 | 100ns | our $VERSION; | ||
21 | # spent 3µs within Variable::Magic::BEGIN@21 which was called
# once (3µs+0s) by B::Hooks::EndOfScope::BEGIN@7 at line 23 | ||||
22 | 1 | 11µs | $VERSION = '0.39'; | ||
23 | 1 | 54µs | 1 | 3µs | } # spent 3µs making 1 call to Variable::Magic::BEGIN@21 |
24 | |||||
25 | =head1 SYNOPSIS | ||||
26 | |||||
27 | use Variable::Magic qw/wizard cast VMG_OP_INFO_NAME/; | ||||
28 | |||||
29 | { # A variable tracer | ||||
30 | my $wiz = wizard set => sub { print "now set to ${$_[0]}!\n" }, | ||||
31 | free => sub { print "destroyed!\n" }; | ||||
32 | |||||
33 | my $a = 1; | ||||
34 | cast $a, $wiz; | ||||
35 | $a = 2; # "now set to 2!" | ||||
36 | } # "destroyed!" | ||||
37 | |||||
38 | { # A hash with a default value | ||||
39 | my $wiz = wizard data => sub { $_[1] }, | ||||
40 | fetch => sub { $_[2] = $_[1] unless exists $_[0]->{$_[2]}; () }, | ||||
41 | store => sub { print "key $_[2] stored in $_[-1]\n" }, | ||||
42 | copy_key => 1, | ||||
43 | op_info => VMG_OP_INFO_NAME; | ||||
44 | |||||
45 | my %h = (_default => 0, apple => 2); | ||||
46 | cast %h, $wiz, '_default'; | ||||
47 | print $h{banana}, "\n"; # "0", because the 'banana' key doesn't exist in %h | ||||
48 | $h{pear} = 1; # "key pear stored in helem" | ||||
49 | } | ||||
50 | |||||
51 | =head1 DESCRIPTION | ||||
52 | |||||
53 | Magic is Perl way of enhancing objects. | ||||
54 | This mechanism lets the user add extra data to any variable and hook syntaxical operations (such as access, assignment or destruction) that can be applied to it. | ||||
55 | With this module, you can add your own magic to any variable without having to write a single line of XS. | ||||
56 | |||||
57 | You'll realize that these magic variables look a lot like tied variables. | ||||
58 | It's not surprising, as tied variables are implemented as a special kind of magic, just like any 'irregular' Perl variable : scalars like C<$!>, C<$(> or C<$^W>, the C<%ENV> and C<%SIG> hashes, the C<@ISA> array, C<vec()> and C<substr()> lvalues, L<threads::shared> variables... | ||||
59 | They all share the same underlying C API, and this module gives you direct access to it. | ||||
60 | |||||
61 | Still, the magic made available by this module differs from tieing and overloading in several ways : | ||||
62 | |||||
63 | =over 4 | ||||
64 | |||||
65 | =item * | ||||
66 | |||||
67 | It isn't copied on assignment. | ||||
68 | |||||
69 | You attach it to variables, not values (as for blessed references). | ||||
70 | |||||
71 | =item * | ||||
72 | |||||
73 | It doesn't replace the original semantics. | ||||
74 | |||||
75 | Magic callbacks usually trigger before the original action take place, and can't prevent it to happen. | ||||
76 | This also makes catching individual events easier than with C<tie>, where you have to provide fallbacks methods for all actions by usually inheriting from the correct C<Tie::Std*> class and overriding individual methods in your own class. | ||||
77 | |||||
78 | =item * | ||||
79 | |||||
80 | It's type-agnostic. | ||||
81 | |||||
82 | The same magic can be applied on scalars, arrays, hashes, subs or globs. | ||||
83 | But the same hook (see below for a list) may trigger differently depending on the the type of the variable. | ||||
84 | |||||
85 | =item * | ||||
86 | |||||
87 | It's mostly invisible at the Perl level. | ||||
88 | |||||
89 | Magical and non-magical variables cannot be distinguished with C<ref>, C<tied> or another trick. | ||||
90 | |||||
91 | =item * | ||||
92 | |||||
93 | It's notably faster. | ||||
94 | |||||
95 | Mainly because perl's way of handling magic is lighter by nature, and because there's no need for any method resolution. | ||||
96 | Also, since you don't have to reimplement all the variable semantics, you only pay for what you actually use. | ||||
97 | |||||
98 | =back | ||||
99 | |||||
100 | The operations that can be overloaded are : | ||||
101 | |||||
102 | =over 4 | ||||
103 | |||||
104 | =item * | ||||
105 | |||||
106 | C<get> | ||||
107 | |||||
108 | This magic is invoked when the variable is evaluated. | ||||
109 | It is never called for arrays and hashes. | ||||
110 | |||||
111 | =item * | ||||
112 | |||||
113 | C<set> | ||||
114 | |||||
115 | This one is triggered each time the value of the variable changes. | ||||
116 | It is called for array subscripts and slices, but never for hashes. | ||||
117 | |||||
118 | =item * | ||||
119 | |||||
120 | C<len> | ||||
121 | |||||
122 | This magic is a little special : it is called when the 'size' or the 'length' of the variable has to be known by Perl. | ||||
123 | Typically, it's the magic involved when an array is evaluated in scalar context, but also on array assignment and loops (C<for>, C<map> or C<grep>). | ||||
124 | The callback has then to return the length as an integer. | ||||
125 | |||||
126 | =item * | ||||
127 | |||||
128 | C<clear> | ||||
129 | |||||
130 | This magic is invoked when the variable is reset, such as when an array is emptied. | ||||
131 | Please note that this is different from undefining the variable, even though the magic is called when the clearing is a result of the undefine (e.g. for an array, but actually a bug prevent it to work before perl 5.9.5 - see the L<history|/PERL MAGIC HISTORY>). | ||||
132 | |||||
133 | =item * | ||||
134 | |||||
135 | C<free> | ||||
136 | |||||
137 | This one can be considered as an object destructor. | ||||
138 | It happens when the variable goes out of scope, but not when it is undefined. | ||||
139 | |||||
140 | =item * | ||||
141 | |||||
142 | C<copy> | ||||
143 | |||||
144 | This magic only applies to tied arrays and hashes. | ||||
145 | It fires when you try to access or change their elements. | ||||
146 | It is available on your perl iff C<MGf_COPY> is true. | ||||
147 | |||||
148 | =item * | ||||
149 | |||||
150 | C<dup> | ||||
151 | |||||
152 | Invoked when the variable is cloned across threads. | ||||
153 | Currently not available. | ||||
154 | |||||
155 | =item * | ||||
156 | |||||
157 | C<local> | ||||
158 | |||||
159 | When this magic is set on a variable, all subsequent localizations of the variable will trigger the callback. | ||||
160 | It is available on your perl iff C<MGf_LOCAL> is true. | ||||
161 | |||||
162 | =back | ||||
163 | |||||
164 | The following actions only apply to hashes and are available iff C<VMG_UVAR> is true. | ||||
165 | They are referred to as C<uvar> magics. | ||||
166 | |||||
167 | =over 4 | ||||
168 | |||||
169 | =item * | ||||
170 | |||||
171 | C<fetch> | ||||
172 | |||||
173 | This magic happens each time an element is fetched from the hash. | ||||
174 | |||||
175 | =item * | ||||
176 | |||||
177 | C<store> | ||||
178 | |||||
179 | This one is called when an element is stored into the hash. | ||||
180 | |||||
181 | =item * | ||||
182 | |||||
183 | C<exists> | ||||
184 | |||||
185 | This magic fires when a key is tested for existence in the hash. | ||||
186 | |||||
187 | =item * | ||||
188 | |||||
189 | C<delete> | ||||
190 | |||||
191 | This last one triggers when a key is deleted in the hash, regardless of whether the key actually exists in it. | ||||
192 | |||||
193 | =back | ||||
194 | |||||
195 | You can refer to the tests to have more insight of where the different magics are invoked. | ||||
196 | |||||
197 | To prevent any clash between different magics defined with this module, an unique numerical signature is attached to each kind of magic (i.e. each set of callbacks for magic operations). | ||||
198 | At the C level, magic tokens owned by magic created by this module have their C<< mg->mg_private >> field set to C<0x3891> or C<0x3892>, so please don't use these magic (sic) numbers in other extensions. | ||||
199 | |||||
200 | =head1 FUNCTIONS | ||||
201 | |||||
202 | =cut | ||||
203 | |||||
204 | # spent 287µs (10+277) within Variable::Magic::BEGIN@204 which was called
# once (10µs+277µs) by B::Hooks::EndOfScope::BEGIN@7 at line 207 | ||||
205 | 2 | 286µs | require XSLoader; | ||
206 | XSLoader::load(__PACKAGE__, $VERSION); # spent 277µs making 1 call to XSLoader::load | ||||
207 | 1 | 183µs | 1 | 287µs | } # spent 287µs making 1 call to Variable::Magic::BEGIN@204 |
208 | |||||
209 | =head2 C<wizard> | ||||
210 | |||||
211 | wizard data => sub { ... }, | ||||
212 | get => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
213 | set => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
214 | len => sub { my ($ref, $data, $len [, $op]) = @_; ... ; return $newlen; }, | ||||
215 | clear => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
216 | free => sub { my ($ref, $data [, $op]) = @_, ... }, | ||||
217 | copy => sub { my ($ref, $data, $key, $elt [, $op]) = @_; ... }, | ||||
218 | local => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
219 | fetch => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
220 | store => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
221 | exists => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
222 | delete => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
223 | copy_key => $bool, | ||||
224 | op_info => [ 0 | VMG_OP_INFO_NAME | VMG_OP_INFO_OBJECT ] | ||||
225 | |||||
226 | This function creates a 'wizard', an opaque type that holds the magic information. | ||||
227 | It takes a list of keys / values as argument, whose keys can be : | ||||
228 | |||||
229 | =over 4 | ||||
230 | |||||
231 | =item * | ||||
232 | |||||
233 | C<data> | ||||
234 | |||||
235 | A code (or string) reference to a private data constructor. | ||||
236 | It is called each time this magic is cast on a variable, and the scalar returned is used as private data storage for it. | ||||
237 | C<$_[0]> is a reference to the magic object and C<@_[1 .. @_-1]> are all extra arguments that were passed to L</cast>. | ||||
238 | |||||
239 | =item * | ||||
240 | |||||
241 | C<get>, C<set>, C<len>, C<clear>, C<free>, C<copy>, C<local>, C<fetch>, C<store>, C<exists> and C<delete> | ||||
242 | |||||
243 | Code (or string) references to the corresponding magic callbacks. | ||||
244 | You don't have to specify all of them : the magic associated with undefined entries simply won't be hooked. | ||||
245 | In those callbacks, C<$_[0]> is always a reference to the magic object and C<$_[1]> is always the private data (or C<undef> when no private data constructor was supplied). | ||||
246 | |||||
247 | Moreover, when you pass C<< op_info => $num >> to C<wizard>, the last element of C<@_> will be the current op name if C<$num == VMG_OP_INFO_NAME> and a C<B::OP> object representing the current op if C<$num == VMG_OP_INFO_OBJECT>. | ||||
248 | Both have a performance hit, but just getting the name is lighter than getting the op object. | ||||
249 | |||||
250 | Other arguments are specific to the magic hooked : | ||||
251 | |||||
252 | =over 8 | ||||
253 | |||||
254 | =item * | ||||
255 | |||||
256 | C<len> | ||||
257 | |||||
258 | When the variable is an array or a scalar, C<$_[2]> contains the non-magical length. | ||||
259 | The callback can return the new scalar or array length to use, or C<undef> to default to the normal length. | ||||
260 | |||||
261 | =item * | ||||
262 | |||||
263 | C<copy> | ||||
264 | |||||
265 | C<$_[2]> is a either a copy or an alias of the current key, which means that it is useless to try to change or cast magic on it. | ||||
266 | C<$_[3]> is an alias to the current element (i.e. the value). | ||||
267 | |||||
268 | =item * | ||||
269 | |||||
270 | C<fetch>, C<store>, C<exists> and C<delete> | ||||
271 | |||||
272 | C<$_[2]> is an alias to the current key. | ||||
273 | Nothing prevents you from changing it, but be aware that there lurk dangerous side effects. | ||||
274 | For example, it may rightfully be readonly if the key was a bareword. | ||||
275 | You can get a copy instead by passing C<< copy_key => 1 >> to L</wizard>, which allows you to safely assign to C<$_[2]> in order to e.g. redirect the action to another key. | ||||
276 | This however has a little performance drawback because of the copy. | ||||
277 | |||||
278 | =back | ||||
279 | |||||
280 | All the callbacks are expected to return an integer, which is passed straight to the perl magic API. | ||||
281 | However, only the return value of the C<len> callback currently holds a meaning. | ||||
282 | |||||
283 | =back | ||||
284 | |||||
285 | Each callback can be specified as a code or a string reference, in which case the function denoted by the string will be used as the callback. | ||||
286 | |||||
287 | Note that C<free> callbacks are I<never> called during global destruction, as there's no way to ensure that the wizard and the C<free> callback weren't destroyed before the variable. | ||||
288 | |||||
289 | Here's a simple usage example : | ||||
290 | |||||
291 | # A simple scalar tracer | ||||
292 | my $wiz = wizard get => sub { print STDERR "got ${$_[0]}\n" }, | ||||
293 | set => sub { print STDERR "set to ${$_[0]}\n" }, | ||||
294 | free => sub { print STDERR "${$_[0]} was deleted\n" } | ||||
295 | |||||
296 | =cut | ||||
297 | |||||
298 | # spent 38µs (24+14) within Variable::Magic::wizard which was called
# once (24µs+14µs) by namespace::clean::BEGIN@14 at line 47 of B/Hooks/EndOfScope.pm | ||||
299 | 11 | 39µs | croak 'Wrong number of arguments for wizard()' if @_ % 2; | ||
300 | my %opts = @_; | ||||
301 | my @keys = qw/data op_info get set len clear free/; | ||||
302 | push @keys, 'copy' if MGf_COPY; | ||||
303 | push @keys, 'dup' if MGf_DUP; | ||||
304 | push @keys, 'local' if MGf_LOCAL; | ||||
305 | push @keys, qw/fetch store exists delete copy_key/ if VMG_UVAR; | ||||
306 | my $ret = eval { _wizard(map $opts{$_}, @keys) }; # spent 14µs making 1 call to Variable::Magic::_wizard | ||||
307 | if (my $err = $@) { | ||||
308 | $err =~ s/\sat\s+.*?\n//; | ||||
309 | croak $err; | ||||
310 | } | ||||
311 | return $ret; | ||||
312 | } | ||||
313 | |||||
314 | =head2 C<cast> | ||||
315 | |||||
316 | cast [$@%&*]var, $wiz, ... | ||||
317 | |||||
318 | This function associates C<$wiz> magic to the variable supplied, without overwriting any other kind of magic. | ||||
319 | It returns true on success or when C<$wiz> magic is already present, and croaks on error. | ||||
320 | All extra arguments specified after C<$wiz> are passed to the private data constructor in C<@_[1 .. @_-1]>. | ||||
321 | If the variable isn't a hash, any C<uvar> callback of the wizard is safely ignored. | ||||
322 | |||||
323 | # Casts $wiz onto $x, and pass '1' to the data constructor. | ||||
324 | my $x; | ||||
325 | cast $x, $wiz, 1; | ||||
326 | |||||
327 | The C<var> argument can be an array or hash value. | ||||
328 | Magic for those behaves like for any other scalar, except that it is dispelled when the entry is deleted from the container. | ||||
329 | For example, if you want to call C<POSIX::tzset> each time the C<'TZ'> environment variable is changed in C<%ENV>, you can use : | ||||
330 | |||||
331 | use POSIX; | ||||
332 | cast $ENV{TZ}, wizard set => sub { POSIX::tzset(); () }; | ||||
333 | |||||
334 | If you want to overcome the possible deletion of the C<'TZ'> entry, you have no choice but to rely on C<store> uvar magic. | ||||
335 | |||||
336 | =head2 C<getdata> | ||||
337 | |||||
338 | getdata [$@%&*]var, $wiz | ||||
339 | |||||
340 | This accessor fetches the private data associated with the magic C<$wiz> in the variable. | ||||
341 | It croaks when C<$wiz> do not represent a valid magic object, and returns an empty list if no such magic is attached to the variable or when the wizard has no data constructor. | ||||
342 | |||||
343 | # Get the attached data, or undef if the wizard does not attach any. | ||||
344 | my $data = getdata $x, $wiz; | ||||
345 | |||||
346 | =head2 C<dispell> | ||||
347 | |||||
348 | dispell [$@%&*]variable, $wiz | ||||
349 | |||||
350 | The exact opposite of L</cast> : it dissociates C<$wiz> magic from the variable. | ||||
351 | This function returns true on success, C<0> when no magic represented by C<$wiz> could be found in the variable, and croaks if the supplied wizard is invalid. | ||||
352 | |||||
353 | # Dispell now. | ||||
354 | die 'no such magic in $x' unless dispell $x, $wiz; | ||||
355 | |||||
356 | =head1 CONSTANTS | ||||
357 | |||||
358 | =head2 C<MGf_COPY> | ||||
359 | |||||
360 | Evaluates to true iff the 'copy' magic is available. | ||||
361 | |||||
362 | =head2 C<MGf_DUP> | ||||
363 | |||||
364 | Evaluates to true iff the 'dup' magic is available. | ||||
365 | |||||
366 | =head2 C<MGf_LOCAL> | ||||
367 | |||||
368 | Evaluates to true iff the 'local' magic is available. | ||||
369 | |||||
370 | =head2 C<VMG_UVAR> | ||||
371 | |||||
372 | When this constant is true, you can use the C<fetch,store,exists,delete> callbacks on hashes. | ||||
373 | |||||
374 | =head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN> | ||||
375 | |||||
376 | True for perls that don't call 'len' magic when you push an element in a magical array. | ||||
377 | Starting from perl 5.11.0, this only refers to pushes in non-void context and hence is false. | ||||
378 | |||||
379 | =head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID> | ||||
380 | |||||
381 | True for perls that don't call 'len' magic when you push in void context an element in a magical array. | ||||
382 | |||||
383 | =head2 C<VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID> | ||||
384 | |||||
385 | True for perls that don't call 'len' magic when you unshift in void context an element in a magical array. | ||||
386 | |||||
387 | =head2 C<VMG_COMPAT_ARRAY_UNDEF_CLEAR> | ||||
388 | |||||
389 | True for perls that call 'clear' magic when undefining magical arrays. | ||||
390 | |||||
391 | =head2 C<VMG_COMPAT_SCALAR_LENGTH_NOLEN> | ||||
392 | |||||
393 | True for perls that don't call 'len' magic when taking the C<length> of a magical scalar. | ||||
394 | |||||
395 | =head2 C<VMG_PERL_PATCHLEVEL> | ||||
396 | |||||
397 | The perl patchlevel this module was built with, or C<0> for non-debugging perls. | ||||
398 | |||||
399 | =head2 C<VMG_THREADSAFE> | ||||
400 | |||||
401 | True iff this module could have been built with thread-safety features enabled. | ||||
402 | |||||
403 | =head2 C<VMG_FORKSAFE> | ||||
404 | |||||
405 | True iff this module could have been built with fork-safety features enabled. | ||||
406 | This will always be true except on Windows where it's false for perl 5.10.0 and below . | ||||
407 | |||||
408 | =head2 C<VMG_OP_INFO_NAME> | ||||
409 | |||||
410 | Value to pass with C<op_info> to get the current op name in the magic callbacks. | ||||
411 | |||||
412 | =head2 C<VMG_OP_INFO_OBJECT> | ||||
413 | |||||
414 | Value to pass with C<op_info> to get a C<B::OP> object representing the current op in the magic callbacks. | ||||
415 | |||||
416 | =head1 COOKBOOK | ||||
417 | |||||
418 | =head2 Associate an object to any perl variable | ||||
419 | |||||
420 | This can be useful for passing user data through limited APIs. | ||||
421 | |||||
422 | { | ||||
423 | package Magical::UserData; | ||||
424 | |||||
425 | use Variable::Magic qw/wizard cast getdata/; | ||||
426 | |||||
427 | my $wiz = wizard data => sub { \$_[1] }; | ||||
428 | |||||
429 | sub ud (\[$@%*&]) : lvalue { | ||||
430 | my ($var) = @_; | ||||
431 | my $data = &getdata($var, $wiz); | ||||
432 | unless (defined $data) { | ||||
433 | &cast($var, $wiz); | ||||
434 | $data = &getdata($var, $wiz); | ||||
435 | die "Couldn't cast UserData magic onto the variable" unless defined $data; | ||||
436 | } | ||||
437 | $$data; | ||||
438 | } | ||||
439 | } | ||||
440 | |||||
441 | { | ||||
442 | BEGIN { *ud = \&Magical::UserData::ud } | ||||
443 | |||||
444 | my $cb; | ||||
445 | $cb = sub { print 'Hello, ', ud(&$cb), "!\n" }; | ||||
446 | |||||
447 | ud(&$cb) = 'world'; | ||||
448 | $cb->(); # Hello, world! | ||||
449 | } | ||||
450 | |||||
451 | =head2 Recursively cast magic on datastructures | ||||
452 | |||||
453 | C<cast> can be called from any magical callback, and in particular from C<data>. | ||||
454 | This allows you to recursively cast magic on datastructures : | ||||
455 | |||||
456 | my $wiz; | ||||
457 | $wiz = wizard data => sub { | ||||
458 | my ($var, $depth) = @_; | ||||
459 | $depth ||= 0; | ||||
460 | my $r = ref $var; | ||||
461 | if ($r eq 'ARRAY') { | ||||
462 | &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for @$var; | ||||
463 | } elsif ($r eq 'HASH') { | ||||
464 | &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for values %$var; | ||||
465 | } | ||||
466 | return $depth; | ||||
467 | }, | ||||
468 | free => sub { | ||||
469 | my ($var, $depth) = @_; | ||||
470 | my $r = ref $var; | ||||
471 | print "free $r at depth $depth\n"; | ||||
472 | (); | ||||
473 | }; | ||||
474 | |||||
475 | { | ||||
476 | my %h = ( | ||||
477 | a => [ 1, 2 ], | ||||
478 | b => { c => 3 } | ||||
479 | ); | ||||
480 | cast %h, $wiz; | ||||
481 | } | ||||
482 | |||||
483 | When C<%h> goes out of scope, this will print something among the lines of : | ||||
484 | |||||
485 | free HASH at depth 0 | ||||
486 | free HASH at depth 1 | ||||
487 | free SCALAR at depth 2 | ||||
488 | free ARRAY at depth 1 | ||||
489 | free SCALAR at depth 3 | ||||
490 | free SCALAR at depth 3 | ||||
491 | |||||
492 | Of course, this example does nothing with the values that are added after the C<cast>. | ||||
493 | |||||
494 | =head1 PERL MAGIC HISTORY | ||||
495 | |||||
496 | The places where magic is invoked have changed a bit through perl history. | ||||
497 | Here's a little list of the most recent ones. | ||||
498 | |||||
499 | =over 4 | ||||
500 | |||||
501 | =item * | ||||
502 | |||||
503 | B<5.6.x> | ||||
504 | |||||
505 | I<p14416> : 'copy' and 'dup' magic. | ||||
506 | |||||
507 | =item * | ||||
508 | |||||
509 | B<5.8.9> | ||||
510 | |||||
511 | I<p28160> : Integration of I<p25854> (see below). | ||||
512 | |||||
513 | I<p32542> : Integration of I<p31473> (see below). | ||||
514 | |||||
515 | =item * | ||||
516 | |||||
517 | B<5.9.3> | ||||
518 | |||||
519 | I<p25854> : 'len' magic is no longer called when pushing an element into a magic array. | ||||
520 | |||||
521 | I<p26569> : 'local' magic. | ||||
522 | |||||
523 | =item * | ||||
524 | |||||
525 | B<5.9.5> | ||||
526 | |||||
527 | I<p31064> : Meaningful 'uvar' magic. | ||||
528 | |||||
529 | I<p31473> : 'clear' magic wasn't invoked when undefining an array. | ||||
530 | The bug is fixed as of this version. | ||||
531 | |||||
532 | =item * | ||||
533 | |||||
534 | B<5.10.0> | ||||
535 | |||||
536 | Since C<PERL_MAGIC_uvar> is uppercased, C<hv_magic_check()> triggers 'copy' magic on hash stores for (non-tied) hashes that also have 'uvar' magic. | ||||
537 | |||||
538 | =item * | ||||
539 | |||||
540 | B<5.11.x> | ||||
541 | |||||
542 | I<p32969> : 'len' magic is no longer invoked when calling C<length> with a magical scalar. | ||||
543 | |||||
544 | I<p34908> : 'len' magic is no longer called when pushing / unshifting an element into a magical array in void context. | ||||
545 | The C<push> part was already covered by I<p25854>. | ||||
546 | |||||
547 | I<g9cdcb38b> : 'len' magic is called again when pushing into a magical array in non-void context. | ||||
548 | |||||
549 | =back | ||||
550 | |||||
551 | =head1 EXPORT | ||||
552 | |||||
553 | The functions L</wizard>, L</cast>, L</getdata> and L</dispell> are only exported on request. | ||||
554 | All of them are exported by the tags C<':funcs'> and C<':all'>. | ||||
555 | |||||
556 | All the constants are also only exported on request, either individually or by the tags C<':consts'> and C<':all'>. | ||||
557 | |||||
558 | =cut | ||||
559 | |||||
560 | 3 | 103µs | 2 | 95µs | # spent 51µs (8+43) within Variable::Magic::BEGIN@560 which was called
# once (8µs+43µs) by B::Hooks::EndOfScope::BEGIN@7 at line 560 # spent 51µs making 1 call to Variable::Magic::BEGIN@560
# spent 43µs making 1 call to base::import |
561 | |||||
562 | 1 | 500ns | our @EXPORT = (); | ||
563 | 1 | 6µs | our %EXPORT_TAGS = ( | ||
564 | 'funcs' => [ qw/wizard cast getdata dispell/ ], | ||||
565 | 'consts' => [ | ||||
566 | qw/MGf_COPY MGf_DUP MGf_LOCAL VMG_UVAR/, | ||||
567 | qw/VMG_COMPAT_ARRAY_PUSH_NOLEN VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID/, | ||||
568 | qw/VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID/, | ||||
569 | qw/VMG_COMPAT_ARRAY_UNDEF_CLEAR/, | ||||
570 | qw/VMG_COMPAT_SCALAR_LENGTH_NOLEN/, | ||||
571 | qw/VMG_PERL_PATCHLEVEL/, | ||||
572 | qw/VMG_THREADSAFE VMG_FORKSAFE/, | ||||
573 | qw/VMG_OP_INFO_NAME VMG_OP_INFO_OBJECT/ | ||||
574 | ] | ||||
575 | ); | ||||
576 | 1 | 15µs | our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS; | ||
577 | 1 | 3µs | $EXPORT_TAGS{'all'} = [ @EXPORT_OK ]; | ||
578 | |||||
579 | =head1 CAVEATS | ||||
580 | |||||
581 | If you store a magic object in the private data slot, the magic won't be accessible by L</getdata> since it's not copied by assignment. | ||||
582 | The only way to address this would be to return a reference. | ||||
583 | |||||
584 | If you define a wizard with a C<free> callback and cast it on itself, this destructor won't be called because the wizard will be destroyed first. | ||||
585 | |||||
586 | =head1 DEPENDENCIES | ||||
587 | |||||
588 | L<perl> 5.8. | ||||
589 | |||||
590 | L<Carp> (standard since perl 5), L<XSLoader> (standard since perl 5.006). | ||||
591 | |||||
592 | Copy tests need L<Tie::Array> (standard since perl 5.005) and L<Tie::Hash> (since 5.002). | ||||
593 | |||||
594 | Some uvar tests need L<Hash::Util::FieldHash> (standard since perl 5.009004). | ||||
595 | |||||
596 | Glob tests need L<Symbol> (standard since perl 5.002). | ||||
597 | |||||
598 | Threads tests need L<threads> and L<threads::shared>. | ||||
599 | |||||
600 | =head1 SEE ALSO | ||||
601 | |||||
602 | L<perlguts> and L<perlapi> for internal information about magic. | ||||
603 | |||||
604 | L<perltie> and L<overload> for other ways of enhancing objects. | ||||
605 | |||||
606 | =head1 AUTHOR | ||||
607 | |||||
608 | Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>. | ||||
609 | |||||
610 | You can contact me by mail or on C<irc.perl.org> (vincent). | ||||
611 | |||||
612 | =head1 BUGS | ||||
613 | |||||
614 | Please report any bugs or feature requests to C<bug-variable-magic at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Variable-Magic>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. | ||||
615 | |||||
616 | =head1 SUPPORT | ||||
617 | |||||
618 | You can find documentation for this module with the perldoc command. | ||||
619 | |||||
620 | perldoc Variable::Magic | ||||
621 | |||||
622 | Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Variable-Magic>. | ||||
623 | |||||
624 | =head1 COPYRIGHT & LICENSE | ||||
625 | |||||
626 | Copyright 2007-2009 Vincent Pit, all rights reserved. | ||||
627 | |||||
628 | This program is free software; you can redistribute it and/or modify it | ||||
629 | under the same terms as Perl itself. | ||||
630 | |||||
631 | =cut | ||||
632 | |||||
633 | 1 | 14µs | 1; # End of Variable::Magic | ||
# spent 14µs within Variable::Magic::_wizard which was called
# once (14µs+0s) by Variable::Magic::wizard at line 306 of Variable/Magic.pm | |||||
# spent 29µs (23+6) within Variable::Magic::cast which was called 4 times, avg 7µs/call:
# 4 times (23µs+6µs) by B::Hooks::EndOfScope::on_scope_end at line 58 of B/Hooks/EndOfScope.pm, avg 7µs/call | |||||
# spent 4µs within Variable::Magic::getdata which was called 4 times, avg 900ns/call:
# 4 times (4µs+0s) by B::Hooks::EndOfScope::on_scope_end at line 54 of B/Hooks/EndOfScope.pm, avg 900ns/call |