| Filename | /home/hinrik/perl5/perlbrew/perls/perl-5.13.5/lib/site_perl/5.13.5/x86_64-linux/Variable/Magic.pm |
| Statements | Executed 32 statements in 905µs |
| Calls | P | F | Exclusive Time |
Inclusive Time |
Subroutine |
|---|---|---|---|---|---|
| 7 | 1 | 1 | 69µs | 98µs | Variable::Magic::cast (xsub) |
| 1 | 1 | 1 | 39µs | 48µs | Variable::Magic::wizard |
| 1 | 1 | 1 | 35µs | 35µs | Variable::Magic::BEGIN@3 |
| 7 | 1 | 1 | 16µs | 16µs | Variable::Magic::getdata (xsub) |
| 1 | 1 | 1 | 16µs | 235µs | Variable::Magic::BEGIN@202 |
| 1 | 1 | 1 | 14µs | 93µs | Variable::Magic::BEGIN@576 |
| 1 | 1 | 1 | 11µs | 16µs | Variable::Magic::BEGIN@5 |
| 1 | 1 | 1 | 11µs | 20µs | Variable::Magic::BEGIN@6 |
| 1 | 1 | 1 | 9µs | 9µs | Variable::Magic::_wizard (xsub) |
| 1 | 1 | 1 | 5µs | 5µs | Variable::Magic::BEGIN@19 |
| Line | State ments |
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| 1 | package Variable::Magic; | ||||
| 2 | |||||
| 3 | 2 | 39µs | 1 | 35µs | # spent 35µs within Variable::Magic::BEGIN@3 which was called:
# once (35µs+0s) by B::Hooks::EndOfScope::BEGIN@14 at line 3 # spent 35µs making 1 call to Variable::Magic::BEGIN@3 |
| 4 | |||||
| 5 | 2 | 24µs | 2 | 21µs | # spent 16µs (11+5) within Variable::Magic::BEGIN@5 which was called:
# once (11µs+5µs) by B::Hooks::EndOfScope::BEGIN@14 at line 5 # spent 16µs making 1 call to Variable::Magic::BEGIN@5
# spent 5µs making 1 call to strict::import |
| 6 | 2 | 38µs | 2 | 28µs | # spent 20µs (11+9) within Variable::Magic::BEGIN@6 which was called:
# once (11µs+9µs) by B::Hooks::EndOfScope::BEGIN@14 at line 6 # spent 20µs making 1 call to Variable::Magic::BEGIN@6
# spent 9µs making 1 call to warnings::import |
| 7 | |||||
| 8 | =head1 NAME | ||||
| 9 | |||||
| 10 | Variable::Magic - Associate user-defined magic to variables from Perl. | ||||
| 11 | |||||
| 12 | =head1 VERSION | ||||
| 13 | |||||
| 14 | Version 0.44 | ||||
| 15 | |||||
| 16 | =cut | ||||
| 17 | |||||
| 18 | 1 | 1µs | our $VERSION; | ||
| 19 | # spent 5µs within Variable::Magic::BEGIN@19 which was called:
# once (5µs+0s) by B::Hooks::EndOfScope::BEGIN@14 at line 21 | ||||
| 20 | 1 | 5µs | $VERSION = '0.44'; | ||
| 21 | 1 | 99µs | 1 | 5µs | } # spent 5µs making 1 call to Variable::Magic::BEGIN@19 |
| 22 | |||||
| 23 | =head1 SYNOPSIS | ||||
| 24 | |||||
| 25 | use Variable::Magic qw/wizard cast VMG_OP_INFO_NAME/; | ||||
| 26 | |||||
| 27 | { # A variable tracer | ||||
| 28 | my $wiz = wizard set => sub { print "now set to ${$_[0]}!\n" }, | ||||
| 29 | free => sub { print "destroyed!\n" }; | ||||
| 30 | |||||
| 31 | my $a = 1; | ||||
| 32 | cast $a, $wiz; | ||||
| 33 | $a = 2; # "now set to 2!" | ||||
| 34 | } # "destroyed!" | ||||
| 35 | |||||
| 36 | { # A hash with a default value | ||||
| 37 | my $wiz = wizard data => sub { $_[1] }, | ||||
| 38 | fetch => sub { $_[2] = $_[1] unless exists $_[0]->{$_[2]}; () }, | ||||
| 39 | store => sub { print "key $_[2] stored in $_[-1]\n" }, | ||||
| 40 | copy_key => 1, | ||||
| 41 | op_info => VMG_OP_INFO_NAME; | ||||
| 42 | |||||
| 43 | my %h = (_default => 0, apple => 2); | ||||
| 44 | cast %h, $wiz, '_default'; | ||||
| 45 | print $h{banana}, "\n"; # "0", because the 'banana' key doesn't exist in %h | ||||
| 46 | $h{pear} = 1; # "key pear stored in helem" | ||||
| 47 | } | ||||
| 48 | |||||
| 49 | =head1 DESCRIPTION | ||||
| 50 | |||||
| 51 | Magic is Perl's way of enhancing variables. | ||||
| 52 | This mechanism lets the user add extra data to any variable and hook syntactical operations (such as access, assignment or destruction) that can be applied to it. | ||||
| 53 | With this module, you can add your own magic to any variable without having to write a single line of XS. | ||||
| 54 | |||||
| 55 | You'll realize that these magic variables look a lot like tied variables. | ||||
| 56 | It's not surprising, as tied variables are implemented as a special kind of magic, just like any 'irregular' Perl variable : scalars like C<$!>, 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... | ||||
| 57 | They all share the same underlying C API, and this module gives you direct access to it. | ||||
| 58 | |||||
| 59 | Still, the magic made available by this module differs from tieing and overloading in several ways : | ||||
| 60 | |||||
| 61 | =over 4 | ||||
| 62 | |||||
| 63 | =item * | ||||
| 64 | |||||
| 65 | It isn't copied on assignment. | ||||
| 66 | |||||
| 67 | You attach it to variables, not values (as for blessed references). | ||||
| 68 | |||||
| 69 | =item * | ||||
| 70 | |||||
| 71 | It doesn't replace the original semantics. | ||||
| 72 | |||||
| 73 | Magic callbacks usually get triggered before the original action takes place, and can't prevent it from happening. | ||||
| 74 | 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. | ||||
| 75 | |||||
| 76 | =item * | ||||
| 77 | |||||
| 78 | It's type-agnostic. | ||||
| 79 | |||||
| 80 | The same magic can be applied on scalars, arrays, hashes, subs or globs. | ||||
| 81 | But the same hook (see below for a list) may trigger differently depending on the the type of the variable. | ||||
| 82 | |||||
| 83 | =item * | ||||
| 84 | |||||
| 85 | It's mostly invisible at the Perl level. | ||||
| 86 | |||||
| 87 | Magical and non-magical variables cannot be distinguished with C<ref>, C<tied> or another trick. | ||||
| 88 | |||||
| 89 | =item * | ||||
| 90 | |||||
| 91 | It's notably faster. | ||||
| 92 | |||||
| 93 | Mainly because perl's way of handling magic is lighter by nature, and because there's no need for any method resolution. | ||||
| 94 | Also, since you don't have to reimplement all the variable semantics, you only pay for what you actually use. | ||||
| 95 | |||||
| 96 | =back | ||||
| 97 | |||||
| 98 | The operations that can be overloaded are : | ||||
| 99 | |||||
| 100 | =over 4 | ||||
| 101 | |||||
| 102 | =item * | ||||
| 103 | |||||
| 104 | C<get> | ||||
| 105 | |||||
| 106 | This magic is invoked when the variable is evaluated. | ||||
| 107 | It is never called for arrays and hashes. | ||||
| 108 | |||||
| 109 | =item * | ||||
| 110 | |||||
| 111 | C<set> | ||||
| 112 | |||||
| 113 | This one is triggered each time the value of the variable changes. | ||||
| 114 | It is called for array subscripts and slices, but never for hashes. | ||||
| 115 | |||||
| 116 | =item * | ||||
| 117 | |||||
| 118 | C<len> | ||||
| 119 | |||||
| 120 | This magic is a little special : it is called when the 'size' or the 'length' of the variable has to be known by Perl. | ||||
| 121 | 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>). | ||||
| 122 | The callback has then to return the length as an integer. | ||||
| 123 | |||||
| 124 | =item * | ||||
| 125 | |||||
| 126 | C<clear> | ||||
| 127 | |||||
| 128 | This magic is invoked when the variable is reset, such as when an array is emptied. | ||||
| 129 | 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>). | ||||
| 130 | |||||
| 131 | =item * | ||||
| 132 | |||||
| 133 | C<free> | ||||
| 134 | |||||
| 135 | This one can be considered as an object destructor. | ||||
| 136 | It happens when the variable goes out of scope, but not when it is undefined. | ||||
| 137 | |||||
| 138 | =item * | ||||
| 139 | |||||
| 140 | C<copy> | ||||
| 141 | |||||
| 142 | This magic only applies to tied arrays and hashes. | ||||
| 143 | It fires when you try to access or change their elements. | ||||
| 144 | It is available on your perl iff C<MGf_COPY> is true. | ||||
| 145 | |||||
| 146 | =item * | ||||
| 147 | |||||
| 148 | C<dup> | ||||
| 149 | |||||
| 150 | Invoked when the variable is cloned across threads. | ||||
| 151 | Currently not available. | ||||
| 152 | |||||
| 153 | =item * | ||||
| 154 | |||||
| 155 | C<local> | ||||
| 156 | |||||
| 157 | When this magic is set on a variable, all subsequent localizations of the variable will trigger the callback. | ||||
| 158 | It is available on your perl iff C<MGf_LOCAL> is true. | ||||
| 159 | |||||
| 160 | =back | ||||
| 161 | |||||
| 162 | The following actions only apply to hashes and are available iff C<VMG_UVAR> is true. | ||||
| 163 | They are referred to as C<uvar> magics. | ||||
| 164 | |||||
| 165 | =over 4 | ||||
| 166 | |||||
| 167 | =item * | ||||
| 168 | |||||
| 169 | C<fetch> | ||||
| 170 | |||||
| 171 | This magic happens each time an element is fetched from the hash. | ||||
| 172 | |||||
| 173 | =item * | ||||
| 174 | |||||
| 175 | C<store> | ||||
| 176 | |||||
| 177 | This one is called when an element is stored into the hash. | ||||
| 178 | |||||
| 179 | =item * | ||||
| 180 | |||||
| 181 | C<exists> | ||||
| 182 | |||||
| 183 | This magic fires when a key is tested for existence in the hash. | ||||
| 184 | |||||
| 185 | =item * | ||||
| 186 | |||||
| 187 | C<delete> | ||||
| 188 | |||||
| 189 | This last one triggers when a key is deleted in the hash, regardless of whether the key actually exists in it. | ||||
| 190 | |||||
| 191 | =back | ||||
| 192 | |||||
| 193 | You can refer to the tests to have more insight of where the different magics are invoked. | ||||
| 194 | |||||
| 195 | 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). | ||||
| 196 | 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. | ||||
| 197 | |||||
| 198 | =head1 FUNCTIONS | ||||
| 199 | |||||
| 200 | =cut | ||||
| 201 | |||||
| 202 | # spent 235µs (16+219) within Variable::Magic::BEGIN@202 which was called:
# once (16µs+219µs) by B::Hooks::EndOfScope::BEGIN@14 at line 205 | ||||
| 203 | 1 | 1µs | require XSLoader; | ||
| 204 | 1 | 230µs | 1 | 219µs | XSLoader::load(__PACKAGE__, $VERSION); # spent 219µs making 1 call to XSLoader::load |
| 205 | 1 | 284µs | 1 | 235µs | } # spent 235µs making 1 call to Variable::Magic::BEGIN@202 |
| 206 | |||||
| 207 | =head2 C<wizard> | ||||
| 208 | |||||
| 209 | wizard data => sub { ... }, | ||||
| 210 | get => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
| 211 | set => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
| 212 | len => sub { my ($ref, $data, $len [, $op]) = @_; ... ; return $newlen; }, | ||||
| 213 | clear => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
| 214 | free => sub { my ($ref, $data [, $op]) = @_, ... }, | ||||
| 215 | copy => sub { my ($ref, $data, $key, $elt [, $op]) = @_; ... }, | ||||
| 216 | local => sub { my ($ref, $data [, $op]) = @_; ... }, | ||||
| 217 | fetch => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
| 218 | store => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
| 219 | exists => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
| 220 | delete => sub { my ($ref, $data, $key [, $op]) = @_; ... }, | ||||
| 221 | copy_key => $bool, | ||||
| 222 | op_info => [ 0 | VMG_OP_INFO_NAME | VMG_OP_INFO_OBJECT ] | ||||
| 223 | |||||
| 224 | This function creates a 'wizard', an opaque type that holds the magic information. | ||||
| 225 | It takes a list of keys / values as argument, whose keys can be : | ||||
| 226 | |||||
| 227 | =over 4 | ||||
| 228 | |||||
| 229 | =item * | ||||
| 230 | |||||
| 231 | C<data> | ||||
| 232 | |||||
| 233 | A code (or string) reference to a private data constructor. | ||||
| 234 | It is called each time this magic is cast on a variable, and the scalar returned is used as private data storage for it. | ||||
| 235 | C<$_[0]> is a reference to the magic object and C<@_[1 .. @_-1]> are all extra arguments that were passed to L</cast>. | ||||
| 236 | |||||
| 237 | =item * | ||||
| 238 | |||||
| 239 | C<get>, C<set>, C<len>, C<clear>, C<free>, C<copy>, C<local>, C<fetch>, C<store>, C<exists> and C<delete> | ||||
| 240 | |||||
| 241 | Code (or string) references to the corresponding magic callbacks. | ||||
| 242 | You don't have to specify all of them : the magic associated with undefined entries simply won't be hooked. | ||||
| 243 | 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). | ||||
| 244 | |||||
| 245 | 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<$num == VMG_OP_INFO_OBJECT>. | ||||
| 246 | Both have a performance hit, but just getting the name is lighter than getting the op object. | ||||
| 247 | |||||
| 248 | Other arguments are specific to the magic hooked : | ||||
| 249 | |||||
| 250 | =over 8 | ||||
| 251 | |||||
| 252 | =item * | ||||
| 253 | |||||
| 254 | C<len> | ||||
| 255 | |||||
| 256 | When the variable is an array or a scalar, C<$_[2]> contains the non-magical length. | ||||
| 257 | The callback can return the new scalar or array length to use, or C<undef> to default to the normal length. | ||||
| 258 | |||||
| 259 | =item * | ||||
| 260 | |||||
| 261 | C<copy> | ||||
| 262 | |||||
| 263 | C<$_[2]> is a either a copy or an alias of the current key, which means that it is useless to try to change or cast magic on it. | ||||
| 264 | C<$_[3]> is an alias to the current element (i.e. the value). | ||||
| 265 | |||||
| 266 | =item * | ||||
| 267 | |||||
| 268 | C<fetch>, C<store>, C<exists> and C<delete> | ||||
| 269 | |||||
| 270 | C<$_[2]> is an alias to the current key. | ||||
| 271 | Nothing prevents you from changing it, but be aware that there lurk dangerous side effects. | ||||
| 272 | For example, it may rightfully be readonly if the key was a bareword. | ||||
| 273 | You can get a copy instead by passing C<< copy_key => 1 >> to L</wizard>, which allows you to safely assign to C<$_[2]> in order to e.g. redirect the action to another key. | ||||
| 274 | This however has a little performance drawback because of the copy. | ||||
| 275 | |||||
| 276 | =back | ||||
| 277 | |||||
| 278 | All the callbacks are expected to return an integer, which is passed straight to the perl magic API. | ||||
| 279 | However, only the return value of the C<len> callback currently holds a meaning. | ||||
| 280 | |||||
| 281 | =back | ||||
| 282 | |||||
| 283 | 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. | ||||
| 284 | |||||
| 285 | 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. | ||||
| 286 | |||||
| 287 | Here's a simple usage example : | ||||
| 288 | |||||
| 289 | # A simple scalar tracer | ||||
| 290 | my $wiz = wizard get => sub { print STDERR "got ${$_[0]}\n" }, | ||||
| 291 | set => sub { print STDERR "set to ${$_[0]}\n" }, | ||||
| 292 | free => sub { print STDERR "${$_[0]} was deleted\n" } | ||||
| 293 | |||||
| 294 | =cut | ||||
| 295 | |||||
| 296 | # spent 48µs (39+9) within Variable::Magic::wizard which was called:
# once (39µs+9µs) by namespace::clean::BEGIN@17 at line 26 of B/Hooks/EndOfScope.pm | ||||
| 297 | 1 | 2µs | if (@_ % 2) { | ||
| 298 | require Carp; | ||||
| 299 | Carp::croak('Wrong number of arguments for wizard()'); | ||||
| 300 | } | ||||
| 301 | |||||
| 302 | 1 | 4µs | my %opts = @_; | ||
| 303 | |||||
| 304 | 1 | 2µs | my @keys = qw/data op_info get set len clear free/; | ||
| 305 | 1 | 2µs | push @keys, 'copy' if MGf_COPY; | ||
| 306 | 1 | 2µs | push @keys, 'dup' if MGf_DUP; | ||
| 307 | 1 | 1µs | push @keys, 'local' if MGf_LOCAL; | ||
| 308 | 1 | 2µs | push @keys, qw/fetch store exists delete copy_key/ if VMG_UVAR; | ||
| 309 | |||||
| 310 | 1 | 1µs | my ($wiz, $err); | ||
| 311 | { | ||||
| 312 | 2 | 3µs | local $@; | ||
| 313 | 2 | 22µs | 1 | 9µs | $wiz = eval { _wizard(map $opts{$_}, @keys) }; # spent 9µs making 1 call to Variable::Magic::_wizard |
| 314 | 1 | 1µs | $err = $@; | ||
| 315 | } | ||||
| 316 | 1 | 1µs | if ($err) { | ||
| 317 | $err =~ s/\sat\s+.*?\n//; | ||||
| 318 | require Carp; | ||||
| 319 | Carp::croak($err); | ||||
| 320 | } | ||||
| 321 | |||||
| 322 | 1 | 6µs | return $wiz; | ||
| 323 | } | ||||
| 324 | |||||
| 325 | =head2 C<cast> | ||||
| 326 | |||||
| 327 | cast [$@%&*]var, $wiz, ... | ||||
| 328 | |||||
| 329 | This function associates C<$wiz> magic to the variable supplied, without overwriting any other kind of magic. | ||||
| 330 | It returns true on success or when C<$wiz> magic is already present, and croaks on error. | ||||
| 331 | All extra arguments specified after C<$wiz> are passed to the private data constructor in C<@_[1 .. @_-1]>. | ||||
| 332 | If the variable isn't a hash, any C<uvar> callback of the wizard is safely ignored. | ||||
| 333 | |||||
| 334 | # Casts $wiz onto $x, and pass '1' to the data constructor. | ||||
| 335 | my $x; | ||||
| 336 | cast $x, $wiz, 1; | ||||
| 337 | |||||
| 338 | The C<var> argument can be an array or hash value. | ||||
| 339 | Magic for those behaves like for any other scalar, except that it is dispelled when the entry is deleted from the container. | ||||
| 340 | 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 : | ||||
| 341 | |||||
| 342 | use POSIX; | ||||
| 343 | cast $ENV{TZ}, wizard set => sub { POSIX::tzset(); () }; | ||||
| 344 | |||||
| 345 | If you want to overcome the possible deletion of the C<'TZ'> entry, you have no choice but to rely on C<store> uvar magic. | ||||
| 346 | |||||
| 347 | =head2 C<getdata> | ||||
| 348 | |||||
| 349 | getdata [$@%&*]var, $wiz | ||||
| 350 | |||||
| 351 | This accessor fetches the private data associated with the magic C<$wiz> in the variable. | ||||
| 352 | 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. | ||||
| 353 | |||||
| 354 | # Get the attached data, or undef if the wizard does not attach any. | ||||
| 355 | my $data = getdata $x, $wiz; | ||||
| 356 | |||||
| 357 | =head2 C<dispell> | ||||
| 358 | |||||
| 359 | dispell [$@%&*]variable, $wiz | ||||
| 360 | |||||
| 361 | The exact opposite of L</cast> : it dissociates C<$wiz> magic from the variable. | ||||
| 362 | 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. | ||||
| 363 | |||||
| 364 | # Dispell now. | ||||
| 365 | die 'no such magic in $x' unless dispell $x, $wiz; | ||||
| 366 | |||||
| 367 | =head1 CONSTANTS | ||||
| 368 | |||||
| 369 | =head2 C<MGf_COPY> | ||||
| 370 | |||||
| 371 | Evaluates to true iff the 'copy' magic is available. | ||||
| 372 | |||||
| 373 | =head2 C<MGf_DUP> | ||||
| 374 | |||||
| 375 | Evaluates to true iff the 'dup' magic is available. | ||||
| 376 | |||||
| 377 | =head2 C<MGf_LOCAL> | ||||
| 378 | |||||
| 379 | Evaluates to true iff the 'local' magic is available. | ||||
| 380 | |||||
| 381 | =head2 C<VMG_UVAR> | ||||
| 382 | |||||
| 383 | When this constant is true, you can use the C<fetch,store,exists,delete> callbacks on hashes. | ||||
| 384 | |||||
| 385 | =head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN> | ||||
| 386 | |||||
| 387 | True for perls that don't call 'len' magic when you push an element in a magical array. | ||||
| 388 | Starting from perl 5.11.0, this only refers to pushes in non-void context and hence is false. | ||||
| 389 | |||||
| 390 | =head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID> | ||||
| 391 | |||||
| 392 | True for perls that don't call 'len' magic when you push in void context an element in a magical array. | ||||
| 393 | |||||
| 394 | =head2 C<VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID> | ||||
| 395 | |||||
| 396 | True for perls that don't call 'len' magic when you unshift in void context an element in a magical array. | ||||
| 397 | |||||
| 398 | =head2 C<VMG_COMPAT_ARRAY_UNDEF_CLEAR> | ||||
| 399 | |||||
| 400 | True for perls that call 'clear' magic when undefining magical arrays. | ||||
| 401 | |||||
| 402 | =head2 C<VMG_COMPAT_SCALAR_LENGTH_NOLEN> | ||||
| 403 | |||||
| 404 | True for perls that don't call 'len' magic when taking the C<length> of a magical scalar. | ||||
| 405 | |||||
| 406 | =head2 C<VMG_COMPAT_GLOB_GET> | ||||
| 407 | |||||
| 408 | True for perls that call 'get' magic for operations on globs. | ||||
| 409 | |||||
| 410 | =head2 C<VMG_PERL_PATCHLEVEL> | ||||
| 411 | |||||
| 412 | The perl patchlevel this module was built with, or C<0> for non-debugging perls. | ||||
| 413 | |||||
| 414 | =head2 C<VMG_THREADSAFE> | ||||
| 415 | |||||
| 416 | True iff this module could have been built with thread-safety features enabled. | ||||
| 417 | |||||
| 418 | =head2 C<VMG_FORKSAFE> | ||||
| 419 | |||||
| 420 | True iff this module could have been built with fork-safety features enabled. | ||||
| 421 | This will always be true except on Windows where it's false for perl 5.10.0 and below . | ||||
| 422 | |||||
| 423 | =head2 C<VMG_OP_INFO_NAME> | ||||
| 424 | |||||
| 425 | Value to pass with C<op_info> to get the current op name in the magic callbacks. | ||||
| 426 | |||||
| 427 | =head2 C<VMG_OP_INFO_OBJECT> | ||||
| 428 | |||||
| 429 | Value to pass with C<op_info> to get a C<B::OP> object representing the current op in the magic callbacks. | ||||
| 430 | |||||
| 431 | =head1 COOKBOOK | ||||
| 432 | |||||
| 433 | =head2 Associate an object to any perl variable | ||||
| 434 | |||||
| 435 | This technique can be useful for passing user data through limited APIs. | ||||
| 436 | It is similar to using inside-out objects, but without the drawback of having to implement a complex destructor. | ||||
| 437 | |||||
| 438 | { | ||||
| 439 | package Magical::UserData; | ||||
| 440 | |||||
| 441 | use Variable::Magic qw/wizard cast getdata/; | ||||
| 442 | |||||
| 443 | my $wiz = wizard data => sub { \$_[1] }; | ||||
| 444 | |||||
| 445 | sub ud (\[$@%*&]) : lvalue { | ||||
| 446 | my ($var) = @_; | ||||
| 447 | my $data = &getdata($var, $wiz); | ||||
| 448 | unless (defined $data) { | ||||
| 449 | $data = \(my $slot); | ||||
| 450 | &cast($var, $wiz, $slot) | ||||
| 451 | or die "Couldn't cast UserData magic onto the variable"; | ||||
| 452 | } | ||||
| 453 | $$data; | ||||
| 454 | } | ||||
| 455 | } | ||||
| 456 | |||||
| 457 | { | ||||
| 458 | BEGIN { *ud = \&Magical::UserData::ud } | ||||
| 459 | |||||
| 460 | my $cb; | ||||
| 461 | $cb = sub { print 'Hello, ', ud(&$cb), "!\n" }; | ||||
| 462 | |||||
| 463 | ud(&$cb) = 'world'; | ||||
| 464 | $cb->(); # Hello, world! | ||||
| 465 | } | ||||
| 466 | |||||
| 467 | =head2 Recursively cast magic on datastructures | ||||
| 468 | |||||
| 469 | C<cast> can be called from any magical callback, and in particular from C<data>. | ||||
| 470 | This allows you to recursively cast magic on datastructures : | ||||
| 471 | |||||
| 472 | my $wiz; | ||||
| 473 | $wiz = wizard data => sub { | ||||
| 474 | my ($var, $depth) = @_; | ||||
| 475 | $depth ||= 0; | ||||
| 476 | my $r = ref $var; | ||||
| 477 | if ($r eq 'ARRAY') { | ||||
| 478 | &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for @$var; | ||||
| 479 | } elsif ($r eq 'HASH') { | ||||
| 480 | &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for values %$var; | ||||
| 481 | } | ||||
| 482 | return $depth; | ||||
| 483 | }, | ||||
| 484 | free => sub { | ||||
| 485 | my ($var, $depth) = @_; | ||||
| 486 | my $r = ref $var; | ||||
| 487 | print "free $r at depth $depth\n"; | ||||
| 488 | (); | ||||
| 489 | }; | ||||
| 490 | |||||
| 491 | { | ||||
| 492 | my %h = ( | ||||
| 493 | a => [ 1, 2 ], | ||||
| 494 | b => { c => 3 } | ||||
| 495 | ); | ||||
| 496 | cast %h, $wiz; | ||||
| 497 | } | ||||
| 498 | |||||
| 499 | When C<%h> goes out of scope, this will print something among the lines of : | ||||
| 500 | |||||
| 501 | free HASH at depth 0 | ||||
| 502 | free HASH at depth 1 | ||||
| 503 | free SCALAR at depth 2 | ||||
| 504 | free ARRAY at depth 1 | ||||
| 505 | free SCALAR at depth 3 | ||||
| 506 | free SCALAR at depth 3 | ||||
| 507 | |||||
| 508 | Of course, this example does nothing with the values that are added after the C<cast>. | ||||
| 509 | |||||
| 510 | =head1 PERL MAGIC HISTORY | ||||
| 511 | |||||
| 512 | The places where magic is invoked have changed a bit through perl history. | ||||
| 513 | Here's a little list of the most recent ones. | ||||
| 514 | |||||
| 515 | =over 4 | ||||
| 516 | |||||
| 517 | =item * | ||||
| 518 | |||||
| 519 | B<5.6.x> | ||||
| 520 | |||||
| 521 | I<p14416> : 'copy' and 'dup' magic. | ||||
| 522 | |||||
| 523 | =item * | ||||
| 524 | |||||
| 525 | B<5.8.9> | ||||
| 526 | |||||
| 527 | I<p28160> : Integration of I<p25854> (see below). | ||||
| 528 | |||||
| 529 | I<p32542> : Integration of I<p31473> (see below). | ||||
| 530 | |||||
| 531 | =item * | ||||
| 532 | |||||
| 533 | B<5.9.3> | ||||
| 534 | |||||
| 535 | I<p25854> : 'len' magic is no longer called when pushing an element into a magic array. | ||||
| 536 | |||||
| 537 | I<p26569> : 'local' magic. | ||||
| 538 | |||||
| 539 | =item * | ||||
| 540 | |||||
| 541 | B<5.9.5> | ||||
| 542 | |||||
| 543 | I<p31064> : Meaningful 'uvar' magic. | ||||
| 544 | |||||
| 545 | I<p31473> : 'clear' magic wasn't invoked when undefining an array. | ||||
| 546 | The bug is fixed as of this version. | ||||
| 547 | |||||
| 548 | =item * | ||||
| 549 | |||||
| 550 | B<5.10.0> | ||||
| 551 | |||||
| 552 | 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. | ||||
| 553 | |||||
| 554 | =item * | ||||
| 555 | |||||
| 556 | B<5.11.x> | ||||
| 557 | |||||
| 558 | I<p32969> : 'len' magic is no longer invoked when calling C<length> with a magical scalar. | ||||
| 559 | |||||
| 560 | I<p34908> : 'len' magic is no longer called when pushing / unshifting an element into a magical array in void context. | ||||
| 561 | The C<push> part was already covered by I<p25854>. | ||||
| 562 | |||||
| 563 | I<g9cdcb38b> : 'len' magic is called again when pushing into a magical array in non-void context. | ||||
| 564 | |||||
| 565 | =back | ||||
| 566 | |||||
| 567 | =head1 EXPORT | ||||
| 568 | |||||
| 569 | The functions L</wizard>, L</cast>, L</getdata> and L</dispell> are only exported on request. | ||||
| 570 | All of them are exported by the tags C<':funcs'> and C<':all'>. | ||||
| 571 | |||||
| 572 | All the constants are also only exported on request, either individually or by the tags C<':consts'> and C<':all'>. | ||||
| 573 | |||||
| 574 | =cut | ||||
| 575 | |||||
| 576 | 2 | 106µs | 2 | 172µs | # spent 93µs (14+79) within Variable::Magic::BEGIN@576 which was called:
# once (14µs+79µs) by B::Hooks::EndOfScope::BEGIN@14 at line 576 # spent 93µs making 1 call to Variable::Magic::BEGIN@576
# spent 79µs making 1 call to base::import |
| 577 | |||||
| 578 | 1 | 1µs | our @EXPORT = (); | ||
| 579 | 1 | 5µs | our %EXPORT_TAGS = ( | ||
| 580 | 'funcs' => [ qw/wizard cast getdata dispell/ ], | ||||
| 581 | 'consts' => [ qw/ | ||||
| 582 | MGf_COPY MGf_DUP MGf_LOCAL VMG_UVAR | ||||
| 583 | VMG_COMPAT_ARRAY_PUSH_NOLEN VMG_COMPAT_ARRAY_PUSH_NOLEN_VOID | ||||
| 584 | VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID | ||||
| 585 | VMG_COMPAT_ARRAY_UNDEF_CLEAR | ||||
| 586 | VMG_COMPAT_SCALAR_LENGTH_NOLEN | ||||
| 587 | VMG_COMPAT_GLOB_GET | ||||
| 588 | VMG_PERL_PATCHLEVEL | ||||
| 589 | VMG_THREADSAFE VMG_FORKSAFE | ||||
| 590 | VMG_OP_INFO_NAME VMG_OP_INFO_OBJECT | ||||
| 591 | / ], | ||||
| 592 | ); | ||||
| 593 | 1 | 11µs | our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS; | ||
| 594 | 1 | 4µs | $EXPORT_TAGS{'all'} = [ @EXPORT_OK ]; | ||
| 595 | |||||
| 596 | =head1 CAVEATS | ||||
| 597 | |||||
| 598 | 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. | ||||
| 599 | The only way to address this would be to return a reference. | ||||
| 600 | |||||
| 601 | 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. | ||||
| 602 | |||||
| 603 | =head1 DEPENDENCIES | ||||
| 604 | |||||
| 605 | L<perl> 5.8. | ||||
| 606 | |||||
| 607 | L<Carp> (standard since perl 5), L<XSLoader> (standard since perl 5.006). | ||||
| 608 | |||||
| 609 | Copy tests need L<Tie::Array> (standard since perl 5.005) and L<Tie::Hash> (since 5.002). | ||||
| 610 | |||||
| 611 | Some uvar tests need L<Hash::Util::FieldHash> (standard since perl 5.009004). | ||||
| 612 | |||||
| 613 | Glob tests need L<Symbol> (standard since perl 5.002). | ||||
| 614 | |||||
| 615 | Threads tests need L<threads> and L<threads::shared>. | ||||
| 616 | |||||
| 617 | =head1 SEE ALSO | ||||
| 618 | |||||
| 619 | L<perlguts> and L<perlapi> for internal information about magic. | ||||
| 620 | |||||
| 621 | L<perltie> and L<overload> for other ways of enhancing objects. | ||||
| 622 | |||||
| 623 | =head1 AUTHOR | ||||
| 624 | |||||
| 625 | Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>. | ||||
| 626 | |||||
| 627 | You can contact me by mail or on C<irc.perl.org> (vincent). | ||||
| 628 | |||||
| 629 | =head1 BUGS | ||||
| 630 | |||||
| 631 | 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. | ||||
| 632 | |||||
| 633 | =head1 SUPPORT | ||||
| 634 | |||||
| 635 | You can find documentation for this module with the perldoc command. | ||||
| 636 | |||||
| 637 | perldoc Variable::Magic | ||||
| 638 | |||||
| 639 | Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Variable-Magic>. | ||||
| 640 | |||||
| 641 | =head1 COPYRIGHT & LICENSE | ||||
| 642 | |||||
| 643 | Copyright 2007,2008,2009,2010 Vincent Pit, all rights reserved. | ||||
| 644 | |||||
| 645 | This program is free software; you can redistribute it and/or modify it | ||||
| 646 | under the same terms as Perl itself. | ||||
| 647 | |||||
| 648 | =cut | ||||
| 649 | |||||
| 650 | 1 | 7µs | 1; # End of Variable::Magic | ||
# spent 9µs within Variable::Magic::_wizard which was called:
# once (9µs+0s) by Variable::Magic::wizard at line 313 | |||||
# spent 98µs (69+28) within Variable::Magic::cast which was called 7 times, avg 14µs/call:
# 7 times (69µs+28µs) by B::Hooks::EndOfScope::on_scope_end at line 37 of B/Hooks/EndOfScope.pm, avg 14µs/call | |||||
# spent 16µs within Variable::Magic::getdata which was called 7 times, avg 2µs/call:
# 7 times (16µs+0s) by B::Hooks::EndOfScope::on_scope_end at line 33 of B/Hooks/EndOfScope.pm, avg 2µs/call |