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For t/test-parsing
  Run on Sun Nov 14 09:49:57 2010
Reported on Sun Nov 14 09:50:06 2010

File /usr/local/lib/perl/5.10.0/Variable/Magic.pm
Statements Executed 37
Total Time 0.001071 seconds
Subroutines — ordered by exclusive time
Calls P F Exclusive
Time
Inclusive
Time
Subroutine
91277µs77µsVariable::Magic::::castVariable::Magic::cast(xsub)
91259µs59µsVariable::Magic::::getdataVariable::Magic::getdata(xsub)
21231µs31µsVariable::Magic::::_wizardVariable::Magic::_wizard(xsub)
11128µs59µsVariable::Magic::::wizardVariable::Magic::wizard
0000s0sVariable::Magic::::BEGINVariable::Magic::BEGIN
LineStmts.Exclusive
Time
Avg.Code
1package Variable::Magic;
2
3331µs10µsuse 5.008;
4
5325µs8µsuse strict;
# spent 11µs making 1 call to strict::import
6336µs12µsuse warnings;
# spent 24µs making 1 call to warnings::import
7
8359µs20µsuse Carp qw/croak/;
# spent 48µs making 1 call to Exporter::import
9
10=head1 NAME
11
12Variable::Magic - Associate user-defined magic to variables from Perl.
13
14=head1 VERSION
15
16Version 0.35
17
18=cut
19
201200ns200nsour $VERSION;
21BEGIN {
2211µs1µs $VERSION = '0.35';
23177µs77µs}
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 $h{pear} = 1; # "key pear stored in helem"
49 }
50
51=head1 DESCRIPTION
52
53Magic is Perl way of enhancing objects.
54This mechanism lets the user add extra data to any variable and hook syntaxical operations (such as access, assignment or destruction) that can be applied to it.
55With this module, you can add your own magic to any variable without having to write a single line of XS.
56
57You'll realize that these magic variables look a lot like tied variables.
58It's not surprising, as tied variables are implemented as a special kind of magic, just like any 'irregular' Perl variable : scalars like C<$!>, 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...
59They all share the same underlying C API, and this module gives you direct access to it.
60
61Still, the magic made available by this module differs from tieing and overloading in several ways :
62
63=over 4
64
65=item *
66
67It isn't copied on assignment.
68
69You attach it to variables, not values (as for blessed references).
70
71=item *
72
73It doesn't replace the original semantics.
74
75Magic callbacks usually trigger before the original action take place, and can't prevent it to happen.
76This 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
80It's type-agnostic.
81
82The same magic can be applied on scalars, arrays, hashes, subs or globs.
83But the same hook (see below for a list) may trigger differently depending on the the type of the variable.
84
85=item *
86
87It's mostly invisible at the Perl level.
88
89Magical and non-magical variables cannot be distinguished with C<ref>, C<tied> or another trick.
90
91=item *
92
93It's notably faster.
94
95Mainly because perl's way of handling magic is lighter by nature, and because there's no need for any method resolution.
96Also, since you don't have to reimplement all the variable semantics, you only pay for what you actually use.
97
98=back
99
100The operations that can be overloaded are :
101
102=over 4
103
104=item *
105
106C<get>
107
108This magic is invoked when the variable is evaluated (does not include array/hash subscripts and slices).
109
110=item *
111
112C<set>
113
114This one is triggered each time the value of the variable changes (includes array/hash subscripts and slices).
115
116=item *
117
118C<len>
119
120This magic is a little special : it is called when the 'size' or the 'length' of the variable has to be known by Perl.
121Typically, 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>).
122The callback has then to return the length as an integer.
123
124=item *
125
126C<clear>
127
128This magic is invoked when the variable is reset, such as when an array is emptied.
129Please 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>).
130
131=item *
132
133C<free>
134
135This one can be considered as an object destructor.
136It happens when the variable goes out of scope, but not when it is undefined.
137
138=item *
139
140C<copy>
141
142This magic only applies to tied arrays and hashes.
143It fires when you try to access or change their elements.
144It is available on your perl iff C<MGf_COPY> is true.
145
146=item *
147
148C<dup>
149
150Invoked when the variable is cloned across threads.
151Currently not available.
152
153=item *
154
155C<local>
156
157When this magic is set on a variable, all subsequent localizations of the variable will trigger the callback.
158It is available on your perl iff C<MGf_LOCAL> is true.
159
160=back
161
162The following actions only apply to hashes and are available iff C<VMG_UVAR> is true.
163They are referred to as C<uvar> magics.
164
165=over 4
166
167=item *
168
169C<fetch>
170
171This magic happens each time an element is fetched from the hash.
172
173=item *
174
175C<store>
176
177This one is called when an element is stored into the hash.
178
179=item *
180
181C<exists>
182
183This magic fires when a key is tested for existence in the hash.
184
185=item *
186
187C<delete>
188
189This last one triggers when a key is deleted in the hash, regardless of whether the key actually exists in it.
190
191=back
192
193You can refer to the tests to have more insight of where the different magics are invoked.
194
195To 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).
196At 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.
197
198=head1 FUNCTIONS
199
200=cut
201
202BEGIN {
2032306µs153µs require XSLoader;
204 XSLoader::load(__PACKAGE__, $VERSION);
# spent 297µs making 1 call to XSLoader::load
2051287µs287µs}
206
207=head2 C<wizard>
208
209 wizard sig => ...,
210 data => sub { ... },
211 get => sub { my ($ref, $data [, $op]) = @_; ... },
212 set => sub { my ($ref, $data [, $op]) = @_; ... },
213 len => sub { my ($ref, $data, $len [, $op]) = @_; ... ; return $newlen; },
214 clear => sub { my ($ref, $data [, $op]) = @_; ... },
215 free => sub { my ($ref, $data [, $op]) = @_, ... },
216 copy => sub { my ($ref, $data, $key, $elt [, $op]) = @_; ... },
217 local => sub { my ($ref, $data [, $op]) = @_; ... },
218 fetch => sub { my ($ref, $data, $key [, $op]) = @_; ... },
219 store => sub { my ($ref, $data, $key [, $op]) = @_; ... },
220 exists => sub { my ($ref, $data, $key [, $op]) = @_; ... },
221 delete => sub { my ($ref, $data, $key [, $op]) = @_; ... },
222 copy_key => $bool,
223 op_info => [ 0 | VMG_OP_INFO_NAME | VMG_OP_INFO_OBJECT ]
224
225This function creates a 'wizard', an opaque type that holds the magic information.
226It takes a list of keys / values as argument, whose keys can be :
227
228=over 4
229
230=item *
231
232C<sig>
233
234The numerical signature.
235If not specified or undefined, a random signature is generated.
236If the signature matches an already defined magic, then the existant magic object is returned.
237
238=item *
239
240C<data>
241
242A code reference to a private data constructor.
243It is called each time this magic is cast on a variable, and the scalar returned is used as private data storage for it.
244C<$_[0]> is a reference to the magic object and C<@_[1 .. @_-1]> are all extra arguments that were passed to L</cast>.
245
246=item *
247
248C<get>, C<set>, C<len>, C<clear>, C<free>, C<copy>, C<local>, C<fetch>, C<store>, C<exists> and C<delete>
249
250Code references to the corresponding magic callbacks.
251You don't have to specify all of them : the magic associated with undefined entries simply won't be hooked.
252In 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).
253
254Moreover, 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<$num == VMG_OP_INFO_OBJECT>.
255Both have a performance hit, but just getting the name is lighter than getting the op object.
256
257Other arguments are specific to the magic hooked :
258
259=over 8
260
261=item *
262
263C<len>
264
265When the variable is an array or a scalar, C<$_[2]> contains the non-magical length.
266The callback can return the new scalar or array length to use, or C<undef> to default to the normal length.
267
268=item *
269
270C<copy>
271
272C<$_[2]> is a either a copy or an alias of the current key, which means that it is useless to try to change or cast magic on it.
273C<$_[3]> is an alias to the current element (i.e. the value).
274
275=item *
276
277C<fetch>, C<store>, C<exists> and C<delete>
278
279C<$_[2]> is an alias to the current key.
280Nothing prevents you from changing it, but be aware that there lurk dangerous side effects.
281For example, it may righteously be readonly if the key was a bareword.
282You can get a copy instead by passing C<< copy_key => 1 >> to L</wizard>, which allows you to safely assign to C<$_[2]> in order to e.g. redirect the action to another key.
283This however has a little performance drawback because of the copy.
284
285=back
286
287All the callbacks are expected to return an integer, which is passed straight to the perl magic API.
288However, only the return value of the C<len> callback currently holds a meaning.
289
290=back
291
292 # A simple scalar tracer
293 my $wiz = wizard get => sub { print STDERR "got ${$_[0]}\n" },
294 set => sub { print STDERR "set to ${$_[0]}\n" },
295 free => sub { print STDERR "${$_[0]} was deleted\n" }
296
297Note 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.
298
299=cut
300
301
# spent 59µs (28+31) within Variable::Magic::wizard which was called # once (28µs+31µs) by B::Hooks::EndOfScope::__ANON__[/usr/local/share/perl/5.10.0/B/Hooks/EndOfScope.pm:47] at line 47 of /usr/local/share/perl/5.10.0/B/Hooks/EndOfScope.pm
sub wizard {
3021154µs5µs croak 'Wrong number of arguments for wizard()' if @_ % 2;
303 my %opts = @_;
304 my @keys = qw/sig data op_info get set len clear free/;
305 push @keys, 'copy' if MGf_COPY;
306 push @keys, 'dup' if MGf_DUP;
307 push @keys, 'local' if MGf_LOCAL;
308 push @keys, qw/fetch store exists delete copy_key/ if VMG_UVAR;
309 my $ret = eval { _wizard(map $opts{$_}, @keys) };
# spent 31µs making 1 call to Variable::Magic::_wizard
310 if (my $err = $@) {
311 $err =~ s/\sat\s+.*?\n//;
312 croak $err;
313 }
314 return $ret;
315}
316
317=head2 C<gensig>
318
319With this tool, you can manually generate random magic signature between SIG_MIN and SIG_MAX inclusive.
320That's the way L</wizard> creates them when no signature is supplied.
321
322 # Generate a signature
323 my $sig = gensig;
324
325=head2 C<getsig>
326
327 getsig $wiz
328
329This accessor returns the magic signature of this wizard.
330
331 # Get $wiz signature
332 my $sig = getsig $wiz;
333
334=head2 C<cast>
335
336 cast [$@%&*]var, [$wiz|$sig], ...
337
338This function associates C<$wiz> magic to the variable supplied, without overwriting any other kind of magic.
339You can also supply the numeric signature C<$sig> instead of C<$wiz>.
340It returns true on success or when C<$wiz> magic is already present, and croaks on error or when no magic corresponds to the given signature (in case a C<$sig> was supplied).
341All extra arguments specified after C<$wiz> are passed to the private data constructor in C<@_[1 .. @_-1]>.
342If the variable isn't a hash, any C<uvar> callback of the wizard is safely ignored.
343
344 # Casts $wiz onto $x, and pass '1' to the data constructor.
345 my $x;
346 cast $x, $wiz, 1;
347
348The C<var> argument can be an array or hash value.
349Magic for those behaves like for any other scalar, except that it is dispelled when the entry is deleted from the container.
350For example, if you want to call C<POSIX::tzset> each time the C<'TZ'> environment variable is changed in C<%ENV>, you can use :
351
352 use POSIX;
353 cast $ENV{TZ}, wizard set => sub { POSIX::tzset(); () };
354
355If you want to overcome the possible deletion of the C<'TZ'> entry, you have no choice but to rely on C<store> uvar magic.
356
357C<cast> can be called from any magical callback, and in particular from C<data>.
358This allows you to recursively cast magic on datastructures :
359
360 my $wiz;
361 $wiz = wizard
362 data => sub {
363 my ($var, $depth) = @_;
364 $depth ||= 0;
365 my $r = ref $var;
366 if ($r eq 'ARRAY') {
367 &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for @$var;
368 } elsif ($r eq 'HASH') {
369 &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for values %$var;
370 }
371 return $depth;
372 },
373 free => sub {
374 my ($var, $depth) = @_;
375 my $r = ref $var;
376 print "free $r at depth $depth\n";
377 ();
378 };
379
380 {
381 my %h = (
382 a => [ 1, 2 ],
383 b => { c => 3 }
384 );
385 cast %h, $wiz;
386 }
387
388When C<%h> goes out of scope, this will print something among the lines of :
389
390 free HASH at depth 0
391 free HASH at depth 1
392 free SCALAR at depth 2
393 free ARRAY at depth 1
394 free SCALAR at depth 3
395 free SCALAR at depth 3
396
397Of course, this example does nothing with the values that are added after the C<cast>.
398
399=head2 C<getdata>
400
401 getdata [$@%&*]var, [$wiz|$sig]
402
403This accessor fetches the private data associated with the magic C<$wiz> (or the signature C<$sig>) in the variable.
404It croaks when C<$wiz> or C<$sig> do not represent a current valid magic object attached to the variable, and returns C<undef> when the wizard has no data constructor or when the data is actually C<undef>.
405
406 # Get the attached data, or undef if the wizard does not attach any.
407 my $data = getdata $x, $wiz;
408
409=head2 C<dispell>
410
411 dispell [$@%&*]variable, [$wiz|$sig]
412
413The exact opposite of L</cast> : it dissociates C<$wiz> magic from the variable.
414You can also pass the magic signature C<$sig> as the second argument.
415This function returns true on success, C<0> when no magic represented by C<$wiz> or C<$sig> could be found in the variable, and croaks if the supplied wizard or signature is invalid.
416
417 # Dispell now.
418 die 'no such magic in $x' unless dispell $x, $wiz;
419
420=head1 CONSTANTS
421
422=head2 C<SIG_MIN>
423
424The minimum integer used as a signature for user-defined magic.
425
426=head2 C<SIG_MAX>
427
428The maximum integer used as a signature for user-defined magic.
429
430=head2 C<SIG_NBR>
431
432 SIG_NBR = SIG_MAX - SIG_MIN + 1
433
434=head2 C<MGf_COPY>
435
436Evaluates to true iff the 'copy' magic is available.
437
438=head2 C<MGf_DUP>
439
440Evaluates to true iff the 'dup' magic is available.
441
442=head2 C<MGf_LOCAL>
443
444Evaluates to true iff the 'local' magic is available.
445
446=head2 C<VMG_UVAR>
447
448When this constant is true, you can use the C<fetch,store,exists,delete> callbacks on hashes.
449
450=head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN>
451
452True for perls that don't call 'len' magic when you push an element in a magical array.
453
454=head2 C<VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID>
455
456True for perls that don't call 'len' magic when you unshift in void context an element in a magical array.
457
458=head2 C<VMG_COMPAT_ARRAY_UNDEF_CLEAR>
459
460True for perls that call 'clear' magic when undefining magical arrays.
461
462=head2 C<VMG_COMPAT_SCALAR_LENGTH_NOLEN>
463
464True for perls that don't call 'len' magic when taking the C<length> of a magical scalar.
465
466=head2 C<VMG_PERL_PATCHLEVEL>
467
468The perl patchlevel this module was built with, or C<0> for non-debugging perls.
469
470=head2 C<VMG_THREADSAFE>
471
472True iff this module could have been built with thread-safety features enabled.
473
474=head2 C<VMG_OP_INFO_NAME>
475
476Value to pass with C<op_info> to get the current op name in the magic callbacks.
477
478=head2 C<VMG_OP_INFO_OBJECT>
479
480Value to pass with C<op_info> to get a C<B::OP> object representing the current op in the magic callbacks.
481
482=head1 PERL MAGIC HISTORY
483
484The places where magic is invoked have changed a bit through perl history.
485Here's a little list of the most recent ones.
486
487=over 4
488
489=item *
490
491B<5.6.x>
492
493I<p14416> : 'copy' and 'dup' magic.
494
495=item *
496
497B<5.8.9>
498
499I<p28160> : Integration of I<p25854> (see below).
500
501I<p32542> : Integration of I<p31473> (see below).
502
503=item *
504
505B<5.9.3>
506
507I<p25854> : 'len' magic is no longer called when pushing an element into a magic array.
508
509I<p26569> : 'local' magic.
510
511=item *
512
513B<5.9.5>
514
515I<p31064> : Meaningful 'uvar' magic.
516
517I<p31473> : 'clear' magic wasn't invoked when undefining an array.
518The bug is fixed as of this version.
519
520=item *
521
522B<5.10.0>
523
524Since 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.
525
526=item *
527
528B<5.11.x>
529
530I<p32969> : 'len' magic is no longer invoked when calling C<length> with a magical scalar.
531
532I<p34908> : 'len' magic is no longer called when pushing / unshifting an element into a magical array in void context.
533The C<push> part was already covered by I<p25854>.
534
535=back
536
537=head1 EXPORT
538
539The functions L</wizard>, L</gensig>, L</getsig>, L</cast>, L</getdata> and L</dispell> are only exported on request.
540All of them are exported by the tags C<':funcs'> and C<':all'>.
541
542All the constants are also only exported on request, either individually or by the tags C<':consts'> and C<':all'>.
543
544=cut
545
5463145µs48µsuse base qw/Exporter/;
# spent 82µs making 1 call to base::import
547
5481700ns700nsour @EXPORT = ();
54918µs8µsour %EXPORT_TAGS = (
550 'funcs' => [ qw/wizard gensig getsig cast getdata dispell/ ],
551 'consts' => [
552 qw/SIG_MIN SIG_MAX SIG_NBR MGf_COPY MGf_DUP MGf_LOCAL VMG_UVAR/,
553 qw/VMG_COMPAT_ARRAY_PUSH_NOLEN VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID VMG_COMPAT_ARRAY_UNDEF_CLEAR VMG_COMPAT_SCALAR_LENGTH_NOLEN/,
554 qw/VMG_PERL_PATCHLEVEL/,
555 qw/VMG_THREADSAFE/,
556 qw/VMG_OP_INFO_NAME VMG_OP_INFO_OBJECT/
557 ]
558);
559127µs27µsour @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
56014µs4µs$EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
561
562=head1 CAVEATS
563
564If 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.
565The only way to address this would be to return a reference.
566
567If 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.
568
569=head1 DEPENDENCIES
570
571L<perl> 5.8.
572
573L<Carp> (standard since perl 5), L<XSLoader> (standard since perl 5.006).
574
575Copy tests need L<Tie::Array> (standard since perl 5.005) and L<Tie::Hash> (since 5.002).
576
577Some uvar tests need L<Hash::Util::FieldHash> (standard since perl 5.009004).
578
579Glob tests need L<Symbol> (standard since perl 5.002).
580
581Threads tests need L<threads> and L<threads::shared>.
582
583=head1 SEE ALSO
584
585L<perlguts> and L<perlapi> for internal information about magic.
586
587L<perltie> and L<overload> for other ways of enhancing objects.
588
589=head1 AUTHOR
590
591Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
592
593You can contact me by mail or on C<irc.perl.org> (vincent).
594
595=head1 BUGS
596
597Please 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.
598
599=head1 SUPPORT
600
601You can find documentation for this module with the perldoc command.
602
603 perldoc Variable::Magic
604
605Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Variable-Magic>.
606
607=head1 COPYRIGHT & LICENSE
608
609Copyright 2007-2009 Vincent Pit, all rights reserved.
610
611This program is free software; you can redistribute it and/or modify it
612under the same terms as Perl itself.
613
614=cut
615
616112µs12µs1; # End of Variable::Magic
# spent 31µs within Variable::Magic::_wizard which was called # once (31µs+0s) by Variable::Magic::wizard at line 309 of /usr/local/lib/perl/5.10.0/Variable/Magic.pm
sub Variable::Magic::_wizard; # xsub
# spent 77µs within Variable::Magic::cast which was called 8 times, avg 10µs/call: # 8 times (77µs+0s) by B::Hooks::EndOfScope::on_scope_end at line 58 of /usr/local/share/perl/5.10.0/B/Hooks/EndOfScope.pm, avg 10µs/call
sub Variable::Magic::cast; # xsub
# spent 59µs within Variable::Magic::getdata which was called 8 times, avg 7µs/call: # 8 times (59µs+0s) by B::Hooks::EndOfScope::on_scope_end at line 54 of /usr/local/share/perl/5.10.0/B/Hooks/EndOfScope.pm, avg 7µs/call
sub Variable::Magic::getdata; # xsub