File | /usr/local/lib/perl5/5.10.1/attributes.pm |
Statements Executed | 18 |
Statement Execution Time | 454µs |
Calls | P | F | Exclusive Time |
Inclusive Time |
Subroutine |
---|---|---|---|---|---|
1 | 1 | 1 | 22µs | 28µs | import | attributes::
1 | 1 | 1 | 19µs | 22µs | BEGIN@9 | attributes::
1 | 1 | 1 | 9µs | 15µs | BEGIN@29 | attributes::
1 | 1 | 2 | 6µs | 6µs | bootstrap (xsub) | attributes::
1 | 1 | 2 | 1µs | 1µs | _modify_attrs (xsub) | attributes::
1 | 1 | 2 | 800ns | 800ns | reftype (xsub) | attributes::
0 | 0 | 0 | 0s | 0s | carp | attributes::
0 | 0 | 0 | 0s | 0s | croak | attributes::
0 | 0 | 0 | 0s | 0s | get | attributes::
0 | 0 | 0 | 0s | 0s | require_version | attributes::
Line | State ments |
Time on line |
Calls | Time in subs |
Code |
---|---|---|---|---|---|
1 | package attributes; | ||||
2 | |||||
3 | 1 | 300ns | our $VERSION = 0.09; | ||
4 | |||||
5 | 1 | 1µs | @EXPORT_OK = qw(get reftype); | ||
6 | 1 | 100ns | @EXPORT = (); | ||
7 | 1 | 2µs | %EXPORT_TAGS = (ALL => [@EXPORT, @EXPORT_OK]); | ||
8 | |||||
9 | 3 | 67µs | 2 | 25µs | # spent 22µs (19+3) within attributes::BEGIN@9 which was called
# once (19µs+3µs) by DynaLoader::BEGIN@97 at line 9 # spent 22µs making 1 call to attributes::BEGIN@9
# spent 3µs making 1 call to strict::import |
10 | |||||
11 | sub croak { | ||||
12 | require Carp; | ||||
13 | goto &Carp::croak; | ||||
14 | } | ||||
15 | |||||
16 | sub carp { | ||||
17 | require Carp; | ||||
18 | goto &Carp::carp; | ||||
19 | } | ||||
20 | |||||
21 | ## forward declaration(s) rather than wrapping the bootstrap call in BEGIN{} | ||||
22 | #sub reftype ($) ; | ||||
23 | #sub _fetch_attrs ($) ; | ||||
24 | #sub _guess_stash ($) ; | ||||
25 | #sub _modify_attrs ; | ||||
26 | # | ||||
27 | # The extra trips through newATTRSUB in the interpreter wipe out any savings | ||||
28 | # from avoiding the BEGIN block. Just do the bootstrap now. | ||||
29 | 1 | 347µs | 2 | 22µs | # spent 15µs (9+6) within attributes::BEGIN@29 which was called
# once (9µs+6µs) by DynaLoader::BEGIN@97 at line 29 # spent 15µs making 1 call to attributes::BEGIN@29
# spent 6µs making 1 call to attributes::bootstrap |
30 | |||||
31 | # spent 28µs (22+6) within attributes::import which was called
# once (22µs+6µs) by DynaLoader::BEGIN@97 at line 97 of XSLoader.pm | ||||
32 | 8 | 24µs | @_ > 2 && ref $_[2] or do { | ||
33 | require Exporter; | ||||
34 | goto &Exporter::import; | ||||
35 | }; | ||||
36 | my (undef,$home_stash,$svref,@attrs) = @_; | ||||
37 | |||||
38 | my $svtype = uc reftype($svref); # spent 800ns making 1 call to attributes::reftype | ||||
39 | my $pkgmeth; | ||||
40 | $pkgmeth = UNIVERSAL::can($home_stash, "MODIFY_${svtype}_ATTRIBUTES") # spent 4µs making 1 call to UNIVERSAL::can | ||||
41 | if defined $home_stash && $home_stash ne ''; | ||||
42 | my @badattrs; | ||||
43 | 1 | 5µs | if ($pkgmeth) { | ||
44 | my @pkgattrs = _modify_attrs($svref, @attrs); | ||||
45 | @badattrs = $pkgmeth->($home_stash, $svref, @pkgattrs); | ||||
46 | if (!@badattrs && @pkgattrs) { | ||||
47 | require warnings; | ||||
48 | return unless warnings::enabled('reserved'); | ||||
49 | @pkgattrs = grep { m/\A[[:lower:]]+(?:\z|\()/ } @pkgattrs; | ||||
50 | if (@pkgattrs) { | ||||
51 | for my $attr (@pkgattrs) { | ||||
52 | $attr =~ s/\(.+\z//s; | ||||
53 | } | ||||
54 | my $s = ((@pkgattrs == 1) ? '' : 's'); | ||||
55 | carp "$svtype package attribute$s " . | ||||
56 | "may clash with future reserved word$s: " . | ||||
57 | join(' : ' , @pkgattrs); | ||||
58 | } | ||||
59 | } | ||||
60 | } | ||||
61 | else { | ||||
62 | @badattrs = _modify_attrs($svref, @attrs); # spent 1µs making 1 call to attributes::_modify_attrs | ||||
63 | } | ||||
64 | if (@badattrs) { | ||||
65 | croak "Invalid $svtype attribute" . | ||||
66 | (( @badattrs == 1 ) ? '' : 's') . | ||||
67 | ": " . | ||||
68 | join(' : ', @badattrs); | ||||
69 | } | ||||
70 | } | ||||
71 | |||||
72 | sub get ($) { | ||||
73 | @_ == 1 && ref $_[0] or | ||||
74 | croak 'Usage: '.__PACKAGE__.'::get $ref'; | ||||
75 | my $svref = shift; | ||||
76 | my $svtype = uc reftype $svref; | ||||
77 | my $stash = _guess_stash $svref; | ||||
78 | $stash = caller unless defined $stash; | ||||
79 | my $pkgmeth; | ||||
80 | $pkgmeth = UNIVERSAL::can($stash, "FETCH_${svtype}_ATTRIBUTES") | ||||
81 | if defined $stash && $stash ne ''; | ||||
82 | return $pkgmeth ? | ||||
83 | (_fetch_attrs($svref), $pkgmeth->($stash, $svref)) : | ||||
84 | (_fetch_attrs($svref)) | ||||
85 | ; | ||||
86 | } | ||||
87 | |||||
88 | sub require_version { goto &UNIVERSAL::VERSION } | ||||
89 | |||||
90 | 1 | 7µs | 1; | ||
91 | __END__ | ||||
92 | #The POD goes here | ||||
93 | |||||
94 | =head1 NAME | ||||
95 | |||||
96 | attributes - get/set subroutine or variable attributes | ||||
97 | |||||
98 | =head1 SYNOPSIS | ||||
99 | |||||
100 | sub foo : method ; | ||||
101 | my ($x,@y,%z) : Bent = 1; | ||||
102 | my $s = sub : method { ... }; | ||||
103 | |||||
104 | use attributes (); # optional, to get subroutine declarations | ||||
105 | my @attrlist = attributes::get(\&foo); | ||||
106 | |||||
107 | use attributes 'get'; # import the attributes::get subroutine | ||||
108 | my @attrlist = get \&foo; | ||||
109 | |||||
110 | =head1 DESCRIPTION | ||||
111 | |||||
112 | Subroutine declarations and definitions may optionally have attribute lists | ||||
113 | associated with them. (Variable C<my> declarations also may, but see the | ||||
114 | warning below.) Perl handles these declarations by passing some information | ||||
115 | about the call site and the thing being declared along with the attribute | ||||
116 | list to this module. In particular, the first example above is equivalent to | ||||
117 | the following: | ||||
118 | |||||
119 | use attributes __PACKAGE__, \&foo, 'method'; | ||||
120 | |||||
121 | The second example in the synopsis does something equivalent to this: | ||||
122 | |||||
123 | use attributes (); | ||||
124 | my ($x,@y,%z); | ||||
125 | attributes::->import(__PACKAGE__, \$x, 'Bent'); | ||||
126 | attributes::->import(__PACKAGE__, \@y, 'Bent'); | ||||
127 | attributes::->import(__PACKAGE__, \%z, 'Bent'); | ||||
128 | ($x,@y,%z) = 1; | ||||
129 | |||||
130 | Yes, that's a lot of expansion. | ||||
131 | |||||
132 | B<WARNING>: attribute declarations for variables are still evolving. | ||||
133 | The semantics and interfaces of such declarations could change in | ||||
134 | future versions. They are present for purposes of experimentation | ||||
135 | with what the semantics ought to be. Do not rely on the current | ||||
136 | implementation of this feature. | ||||
137 | |||||
138 | There are only a few attributes currently handled by Perl itself (or | ||||
139 | directly by this module, depending on how you look at it.) However, | ||||
140 | package-specific attributes are allowed by an extension mechanism. | ||||
141 | (See L<"Package-specific Attribute Handling"> below.) | ||||
142 | |||||
143 | The setting of subroutine attributes happens at compile time. | ||||
144 | Variable attributes in C<our> declarations are also applied at compile time. | ||||
145 | However, C<my> variables get their attributes applied at run-time. | ||||
146 | This means that you have to I<reach> the run-time component of the C<my> | ||||
147 | before those attributes will get applied. For example: | ||||
148 | |||||
149 | my $x : Bent = 42 if 0; | ||||
150 | |||||
151 | will neither assign 42 to $x I<nor> will it apply the C<Bent> attribute | ||||
152 | to the variable. | ||||
153 | |||||
154 | An attempt to set an unrecognized attribute is a fatal error. (The | ||||
155 | error is trappable, but it still stops the compilation within that | ||||
156 | C<eval>.) Setting an attribute with a name that's all lowercase | ||||
157 | letters that's not a built-in attribute (such as "foo") will result in | ||||
158 | a warning with B<-w> or C<use warnings 'reserved'>. | ||||
159 | |||||
160 | =head2 What C<import> does | ||||
161 | |||||
162 | In the description it is mentioned that | ||||
163 | |||||
164 | sub foo : method; | ||||
165 | |||||
166 | is equivalent to | ||||
167 | |||||
168 | use attributes __PACKAGE__, \&foo, 'method'; | ||||
169 | |||||
170 | As you might know this calls the C<import> function of C<attributes> at compile | ||||
171 | time with these parameters: 'attributes', the caller's package name, the reference | ||||
172 | to the code and 'method'. | ||||
173 | |||||
174 | attributes->import( __PACKAGE__, \&foo, 'method' ); | ||||
175 | |||||
176 | So you want to know what C<import> actually does? | ||||
177 | |||||
178 | First of all C<import> gets the type of the third parameter ('CODE' in this case). | ||||
179 | C<attributes.pm> checks if there is a subroutine called C<< MODIFY_<reftype>_ATTRIBUTES >> | ||||
180 | in the caller's namespace (here: 'main'). In this case a subroutine C<MODIFY_CODE_ATTRIBUTES> is | ||||
181 | required. Then this method is called to check if you have used a "bad attribute". | ||||
182 | The subroutine call in this example would look like | ||||
183 | |||||
184 | MODIFY_CODE_ATTRIBUTES( 'main', \&foo, 'method' ); | ||||
185 | |||||
186 | C<< MODIFY_<reftype>_ATTRIBUTES >> has to return a list of all "bad attributes". | ||||
187 | If there are any bad attributes C<import> croaks. | ||||
188 | |||||
189 | (See L<"Package-specific Attribute Handling"> below.) | ||||
190 | |||||
191 | =head2 Built-in Attributes | ||||
192 | |||||
193 | The following are the built-in attributes for subroutines: | ||||
194 | |||||
195 | =over 4 | ||||
196 | |||||
197 | =item locked | ||||
198 | |||||
199 | B<5.005 threads only! The use of the "locked" attribute currently | ||||
200 | only makes sense if you are using the deprecated "Perl 5.005 threads" | ||||
201 | implementation of threads.> | ||||
202 | |||||
203 | Setting this attribute is only meaningful when the subroutine or | ||||
204 | method is to be called by multiple threads. When set on a method | ||||
205 | subroutine (i.e., one marked with the B<method> attribute below), | ||||
206 | Perl ensures that any invocation of it implicitly locks its first | ||||
207 | argument before execution. When set on a non-method subroutine, | ||||
208 | Perl ensures that a lock is taken on the subroutine itself before | ||||
209 | execution. The semantics of the lock are exactly those of one | ||||
210 | explicitly taken with the C<lock> operator immediately after the | ||||
211 | subroutine is entered. | ||||
212 | |||||
213 | =item method | ||||
214 | |||||
215 | Indicates that the referenced subroutine is a method. | ||||
216 | This has a meaning when taken together with the B<locked> attribute, | ||||
217 | as described there. It also means that a subroutine so marked | ||||
218 | will not trigger the "Ambiguous call resolved as CORE::%s" warning. | ||||
219 | |||||
220 | =item lvalue | ||||
221 | |||||
222 | Indicates that the referenced subroutine is a valid lvalue and can | ||||
223 | be assigned to. The subroutine must return a modifiable value such | ||||
224 | as a scalar variable, as described in L<perlsub>. | ||||
225 | |||||
226 | =back | ||||
227 | |||||
228 | For global variables there is C<unique> attribute: see L<perlfunc/our>. | ||||
229 | |||||
230 | =head2 Available Subroutines | ||||
231 | |||||
232 | The following subroutines are available for general use once this module | ||||
233 | has been loaded: | ||||
234 | |||||
235 | =over 4 | ||||
236 | |||||
237 | =item get | ||||
238 | |||||
239 | This routine expects a single parameter--a reference to a | ||||
240 | subroutine or variable. It returns a list of attributes, which may be | ||||
241 | empty. If passed invalid arguments, it uses die() (via L<Carp::croak|Carp>) | ||||
242 | to raise a fatal exception. If it can find an appropriate package name | ||||
243 | for a class method lookup, it will include the results from a | ||||
244 | C<FETCH_I<type>_ATTRIBUTES> call in its return list, as described in | ||||
245 | L<"Package-specific Attribute Handling"> below. | ||||
246 | Otherwise, only L<built-in attributes|"Built-in Attributes"> will be returned. | ||||
247 | |||||
248 | =item reftype | ||||
249 | |||||
250 | This routine expects a single parameter--a reference to a subroutine or | ||||
251 | variable. It returns the built-in type of the referenced variable, | ||||
252 | ignoring any package into which it might have been blessed. | ||||
253 | This can be useful for determining the I<type> value which forms part of | ||||
254 | the method names described in L<"Package-specific Attribute Handling"> below. | ||||
255 | |||||
256 | =back | ||||
257 | |||||
258 | Note that these routines are I<not> exported by default. | ||||
259 | |||||
260 | =head2 Package-specific Attribute Handling | ||||
261 | |||||
262 | B<WARNING>: the mechanisms described here are still experimental. Do not | ||||
263 | rely on the current implementation. In particular, there is no provision | ||||
264 | for applying package attributes to 'cloned' copies of subroutines used as | ||||
265 | closures. (See L<perlref/"Making References"> for information on closures.) | ||||
266 | Package-specific attribute handling may change incompatibly in a future | ||||
267 | release. | ||||
268 | |||||
269 | When an attribute list is present in a declaration, a check is made to see | ||||
270 | whether an attribute 'modify' handler is present in the appropriate package | ||||
271 | (or its @ISA inheritance tree). Similarly, when C<attributes::get> is | ||||
272 | called on a valid reference, a check is made for an appropriate attribute | ||||
273 | 'fetch' handler. See L<"EXAMPLES"> to see how the "appropriate package" | ||||
274 | determination works. | ||||
275 | |||||
276 | The handler names are based on the underlying type of the variable being | ||||
277 | declared or of the reference passed. Because these attributes are | ||||
278 | associated with subroutine or variable declarations, this deliberately | ||||
279 | ignores any possibility of being blessed into some package. Thus, a | ||||
280 | subroutine declaration uses "CODE" as its I<type>, and even a blessed | ||||
281 | hash reference uses "HASH" as its I<type>. | ||||
282 | |||||
283 | The class methods invoked for modifying and fetching are these: | ||||
284 | |||||
285 | =over 4 | ||||
286 | |||||
287 | =item FETCH_I<type>_ATTRIBUTES | ||||
288 | |||||
289 | This method is called with two arguments: the relevant package name, | ||||
290 | and a reference to a variable or subroutine for which package-defined | ||||
291 | attributes are desired. The expected return value is a list of | ||||
292 | associated attributes. This list may be empty. | ||||
293 | |||||
294 | =item MODIFY_I<type>_ATTRIBUTES | ||||
295 | |||||
296 | This method is called with two fixed arguments, followed by the list of | ||||
297 | attributes from the relevant declaration. The two fixed arguments are | ||||
298 | the relevant package name and a reference to the declared subroutine or | ||||
299 | variable. The expected return value is a list of attributes which were | ||||
300 | not recognized by this handler. Note that this allows for a derived class | ||||
301 | to delegate a call to its base class, and then only examine the attributes | ||||
302 | which the base class didn't already handle for it. | ||||
303 | |||||
304 | The call to this method is currently made I<during> the processing of the | ||||
305 | declaration. In particular, this means that a subroutine reference will | ||||
306 | probably be for an undefined subroutine, even if this declaration is | ||||
307 | actually part of the definition. | ||||
308 | |||||
309 | =back | ||||
310 | |||||
311 | Calling C<attributes::get()> from within the scope of a null package | ||||
312 | declaration C<package ;> for an unblessed variable reference will | ||||
313 | not provide any starting package name for the 'fetch' method lookup. | ||||
314 | Thus, this circumstance will not result in a method call for package-defined | ||||
315 | attributes. A named subroutine knows to which symbol table entry it belongs | ||||
316 | (or originally belonged), and it will use the corresponding package. | ||||
317 | An anonymous subroutine knows the package name into which it was compiled | ||||
318 | (unless it was also compiled with a null package declaration), and so it | ||||
319 | will use that package name. | ||||
320 | |||||
321 | =head2 Syntax of Attribute Lists | ||||
322 | |||||
323 | An attribute list is a sequence of attribute specifications, separated by | ||||
324 | whitespace or a colon (with optional whitespace). | ||||
325 | Each attribute specification is a simple | ||||
326 | name, optionally followed by a parenthesised parameter list. | ||||
327 | If such a parameter list is present, it is scanned past as for the rules | ||||
328 | for the C<q()> operator. (See L<perlop/"Quote and Quote-like Operators">.) | ||||
329 | The parameter list is passed as it was found, however, and not as per C<q()>. | ||||
330 | |||||
331 | Some examples of syntactically valid attribute lists: | ||||
332 | |||||
333 | switch(10,foo(7,3)) : expensive | ||||
334 | Ugly('\(") :Bad | ||||
335 | _5x5 | ||||
336 | locked method | ||||
337 | |||||
338 | Some examples of syntactically invalid attribute lists (with annotation): | ||||
339 | |||||
340 | switch(10,foo() # ()-string not balanced | ||||
341 | Ugly('(') # ()-string not balanced | ||||
342 | 5x5 # "5x5" not a valid identifier | ||||
343 | Y2::north # "Y2::north" not a simple identifier | ||||
344 | foo + bar # "+" neither a colon nor whitespace | ||||
345 | |||||
346 | =head1 EXPORTS | ||||
347 | |||||
348 | =head2 Default exports | ||||
349 | |||||
350 | None. | ||||
351 | |||||
352 | =head2 Available exports | ||||
353 | |||||
354 | The routines C<get> and C<reftype> are exportable. | ||||
355 | |||||
356 | =head2 Export tags defined | ||||
357 | |||||
358 | The C<:ALL> tag will get all of the above exports. | ||||
359 | |||||
360 | =head1 EXAMPLES | ||||
361 | |||||
362 | Here are some samples of syntactically valid declarations, with annotation | ||||
363 | as to how they resolve internally into C<use attributes> invocations by | ||||
364 | perl. These examples are primarily useful to see how the "appropriate | ||||
365 | package" is found for the possible method lookups for package-defined | ||||
366 | attributes. | ||||
367 | |||||
368 | =over 4 | ||||
369 | |||||
370 | =item 1. | ||||
371 | |||||
372 | Code: | ||||
373 | |||||
374 | package Canine; | ||||
375 | package Dog; | ||||
376 | my Canine $spot : Watchful ; | ||||
377 | |||||
378 | Effect: | ||||
379 | |||||
380 | use attributes (); | ||||
381 | attributes::->import(Canine => \$spot, "Watchful"); | ||||
382 | |||||
383 | =item 2. | ||||
384 | |||||
385 | Code: | ||||
386 | |||||
387 | package Felis; | ||||
388 | my $cat : Nervous; | ||||
389 | |||||
390 | Effect: | ||||
391 | |||||
392 | use attributes (); | ||||
393 | attributes::->import(Felis => \$cat, "Nervous"); | ||||
394 | |||||
395 | =item 3. | ||||
396 | |||||
397 | Code: | ||||
398 | |||||
399 | package X; | ||||
400 | sub foo : locked ; | ||||
401 | |||||
402 | Effect: | ||||
403 | |||||
404 | use attributes X => \&foo, "locked"; | ||||
405 | |||||
406 | =item 4. | ||||
407 | |||||
408 | Code: | ||||
409 | |||||
410 | package X; | ||||
411 | sub Y::x : locked { 1 } | ||||
412 | |||||
413 | Effect: | ||||
414 | |||||
415 | use attributes Y => \&Y::x, "locked"; | ||||
416 | |||||
417 | =item 5. | ||||
418 | |||||
419 | Code: | ||||
420 | |||||
421 | package X; | ||||
422 | sub foo { 1 } | ||||
423 | |||||
424 | package Y; | ||||
425 | BEGIN { *bar = \&X::foo; } | ||||
426 | |||||
427 | package Z; | ||||
428 | sub Y::bar : locked ; | ||||
429 | |||||
430 | Effect: | ||||
431 | |||||
432 | use attributes X => \&X::foo, "locked"; | ||||
433 | |||||
434 | =back | ||||
435 | |||||
436 | This last example is purely for purposes of completeness. You should not | ||||
437 | be trying to mess with the attributes of something in a package that's | ||||
438 | not your own. | ||||
439 | |||||
440 | =head1 MORE EXAMPLES | ||||
441 | |||||
442 | =over 4 | ||||
443 | |||||
444 | =item 1. | ||||
445 | |||||
446 | sub MODIFY_CODE_ATTRIBUTES { | ||||
447 | my ($class,$code,@attrs) = @_; | ||||
448 | |||||
449 | my $allowed = 'MyAttribute'; | ||||
450 | my @bad = grep { $_ ne $allowed } @attrs; | ||||
451 | |||||
452 | return @bad; | ||||
453 | } | ||||
454 | |||||
455 | sub foo : MyAttribute { | ||||
456 | print "foo\n"; | ||||
457 | } | ||||
458 | |||||
459 | This example runs. At compile time C<MODIFY_CODE_ATTRIBUTES> is called. In that | ||||
460 | subroutine, we check if any attribute is disallowed and we return a list of | ||||
461 | these "bad attributes". | ||||
462 | |||||
463 | As we return an empty list, everything is fine. | ||||
464 | |||||
465 | =item 2. | ||||
466 | |||||
467 | sub MODIFY_CODE_ATTRIBUTES { | ||||
468 | my ($class,$code,@attrs) = @_; | ||||
469 | |||||
470 | my $allowed = 'MyAttribute'; | ||||
471 | my @bad = grep{ $_ ne $allowed }@attrs; | ||||
472 | |||||
473 | return @bad; | ||||
474 | } | ||||
475 | |||||
476 | sub foo : MyAttribute Test { | ||||
477 | print "foo\n"; | ||||
478 | } | ||||
479 | |||||
480 | This example is aborted at compile time as we use the attribute "Test" which | ||||
481 | isn't allowed. C<MODIFY_CODE_ATTRIBUTES> returns a list that contains a single | ||||
482 | element ('Test'). | ||||
483 | |||||
484 | =back | ||||
485 | |||||
486 | =head1 SEE ALSO | ||||
487 | |||||
488 | L<perlsub/"Private Variables via my()"> and | ||||
489 | L<perlsub/"Subroutine Attributes"> for details on the basic declarations; | ||||
490 | L<attrs> for the obsolescent form of subroutine attribute specification | ||||
491 | which this module replaces; | ||||
492 | L<perlfunc/use> for details on the normal invocation mechanism. | ||||
493 | |||||
494 | =cut | ||||
495 | |||||
# spent 1µs within attributes::_modify_attrs which was called
# once (1µs+0s) by attributes::import at line 62 of attributes.pm | |||||
# spent 6µs within attributes::bootstrap which was called
# once (6µs+0s) by attributes::BEGIN@29 at line 29 of attributes.pm | |||||
# spent 800ns within attributes::reftype which was called
# once (800ns+0s) by attributes::import at line 38 of attributes.pm |