Commit | Line | Data |
7a63380c |
1 | package Function::Parameters; |
2 | |
7dd35535 |
3 | use v5.14.0; |
4 | |
7a63380c |
5 | use warnings; |
6 | |
63915d26 |
7 | use Carp qw(confess); |
8 | |
db81d362 |
9 | use XSLoader; |
10 | BEGIN { |
e1e43949 |
11 | our $VERSION = '1.00'; |
db81d362 |
12 | XSLoader::load; |
7a63380c |
13 | } |
14 | |
2d5cf47a |
15 | sub _assert_valid_identifier { |
16 | my ($name, $with_dollar) = @_; |
17 | my $bonus = $with_dollar ? '\$' : ''; |
18 | $name =~ /^${bonus}[^\W\d]\w*\z/ |
19 | or confess qq{"$name" doesn't look like a valid identifier}; |
20 | } |
21 | |
b72eb6ee |
22 | sub _assert_valid_attributes { |
23 | my ($attrs) = @_; |
24 | $attrs =~ /^\s*:\s*[^\W\d]\w*\s*(?:(?:\s|:\s*)[^\W\d]\w*\s*)*(?:\(|\z)/ |
25 | or confess qq{"$attrs" doesn't look like valid attributes}; |
26 | } |
27 | |
125c067e |
28 | my @bare_arms = qw(function method); |
2d5cf47a |
29 | my %type_map = ( |
63915d26 |
30 | function => { |
31 | name => 'optional', |
32 | default_arguments => 1, |
33 | check_argument_count => 0, |
e158cf8f |
34 | named_parameters => 1, |
63915d26 |
35 | }, |
7947f7ce |
36 | method => { |
37 | name => 'optional', |
63915d26 |
38 | default_arguments => 1, |
39 | check_argument_count => 0, |
e158cf8f |
40 | named_parameters => 1, |
7947f7ce |
41 | attrs => ':method', |
63915d26 |
42 | shift => '$self', |
d8e5d540 |
43 | invocant => 1, |
7947f7ce |
44 | }, |
a23979e1 |
45 | classmethod => { |
46 | name => 'optional', |
63915d26 |
47 | default_arguments => 1, |
48 | check_argument_count => 0, |
e158cf8f |
49 | named_parameters => 1, |
698e861c |
50 | attributes => ':method', |
63915d26 |
51 | shift => '$class', |
d8e5d540 |
52 | invocant => 1, |
a23979e1 |
53 | }, |
2d5cf47a |
54 | ); |
7817d698 |
55 | for my $k (keys %type_map) { |
56 | $type_map{$k . '_strict'} = { |
57 | %{$type_map{$k}}, |
58 | check_argument_count => 1, |
59 | }; |
60 | } |
c9a39f6b |
61 | |
db81d362 |
62 | sub import { |
63 | my $class = shift; |
7a63380c |
64 | |
fcaf7811 |
65 | if (!@_) { |
66 | @_ = { |
67 | fun => 'function', |
68 | method => 'method', |
69 | }; |
70 | } |
71 | if (@_ == 1 && $_[0] eq ':strict') { |
72 | @_ = { |
73 | fun => 'function_strict', |
74 | method => 'method_strict', |
75 | }; |
76 | } |
125c067e |
77 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
fcaf7811 |
78 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]}; |
125c067e |
79 | } |
7a63380c |
80 | |
125c067e |
81 | my %spec; |
82 | |
83 | my $bare = 0; |
84 | for my $proto (@_) { |
85 | my $item = ref $proto |
86 | ? $proto |
87 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
88 | ; |
ae6e00b5 |
89 | my ($name, $proto_type) = @$item; |
2d5cf47a |
90 | _assert_valid_identifier $name; |
91 | |
ae6e00b5 |
92 | unless (ref $proto_type) { |
93 | # use '||' instead of 'or' to preserve $proto_type in the error message |
94 | $proto_type = $type_map{$proto_type} |
95 | || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
2d5cf47a |
96 | } |
b72eb6ee |
97 | |
ae6e00b5 |
98 | my %type = %$proto_type; |
99 | my %clean; |
10acc8b1 |
100 | |
ae6e00b5 |
101 | $clean{name} = delete $type{name} || 'optional'; |
102 | $clean{name} =~ /^(?:optional|required|prohibited)\z/ |
103 | or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
10acc8b1 |
104 | |
ae6e00b5 |
105 | $clean{shift} = delete $type{shift} || ''; |
10acc8b1 |
106 | _assert_valid_identifier $clean{shift}, 1 if $clean{shift}; |
107 | |
698e861c |
108 | $clean{attrs} = join ' ', map delete $type{$_} || (), qw(attributes attrs); |
10acc8b1 |
109 | _assert_valid_attributes $clean{attrs} if $clean{attrs}; |
125c067e |
110 | |
59f51b8b |
111 | $clean{default_arguments} = |
112 | exists $type{default_arguments} |
113 | ? !!delete $type{default_arguments} |
114 | : 1 |
115 | ; |
63915d26 |
116 | $clean{check_argument_count} = !!delete $type{check_argument_count}; |
d8e5d540 |
117 | $clean{invocant} = !!delete $type{invocant}; |
e158cf8f |
118 | $clean{named_parameters} = !!delete $type{named_parameters}; |
63915d26 |
119 | |
ae6e00b5 |
120 | %type and confess "Invalid keyword property: @{[keys %type]}"; |
121 | |
122 | $spec{$name} = \%clean; |
125c067e |
123 | } |
124 | |
db81d362 |
125 | for my $kw (keys %spec) { |
126 | my $type = $spec{$kw}; |
127 | |
63915d26 |
128 | my $flags = |
129 | $type->{name} eq 'prohibited' ? FLAG_ANON_OK : |
130 | $type->{name} eq 'required' ? FLAG_NAME_OK : |
131 | FLAG_ANON_OK | FLAG_NAME_OK |
132 | ; |
133 | $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments}; |
134 | $flags |= FLAG_CHECK_NARGS if $type->{check_argument_count}; |
d8e5d540 |
135 | $flags |= FLAG_INVOCANT if $type->{invocant}; |
e158cf8f |
136 | $flags |= FLAG_NAMED_PARAMS if $type->{named_parameters}; |
63915d26 |
137 | $^H{HINTK_FLAGS_ . $kw} = $flags; |
ae6e00b5 |
138 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift}; |
10acc8b1 |
139 | $^H{HINTK_ATTRS_ . $kw} = $type->{attrs}; |
db81d362 |
140 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
125c067e |
141 | } |
eeb7df5f |
142 | } |
143 | |
db81d362 |
144 | sub unimport { |
eeb7df5f |
145 | my $class = shift; |
125c067e |
146 | |
db81d362 |
147 | if (!@_) { |
148 | delete $^H{+HINTK_KEYWORDS}; |
125c067e |
149 | return; |
150 | } |
151 | |
db81d362 |
152 | for my $kw (@_) { |
153 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
125c067e |
154 | } |
155 | } |
156 | |
db81d362 |
157 | |
53c979f0 |
158 | our %metadata; |
159 | |
160 | sub _register_info { |
161 | my ( |
162 | $key, |
163 | $declarator, |
164 | $invocant, |
165 | $positional_required, |
166 | $positional_optional, |
167 | $named_required, |
168 | $named_optional, |
169 | $slurpy, |
170 | ) = @_; |
171 | |
172 | my $blob = pack '(Z*)*', |
173 | $declarator, |
174 | $invocant // '', |
175 | join(' ', @$positional_required), |
176 | join(' ', @$positional_optional), |
177 | join(' ', @$named_required), |
178 | join(' ', @$named_optional), |
179 | $slurpy // '', |
180 | ; |
181 | |
182 | $metadata{$key} = $blob; |
183 | } |
184 | |
185 | sub info { |
186 | my ($func) = @_; |
187 | my $key = _cv_root $func or return undef; |
188 | my $blob = $metadata{$key} or return undef; |
189 | my @info = unpack '(Z*)*', $blob; |
190 | require Function::Parameters::Info; |
191 | Function::Parameters::Info->new( |
192 | keyword => $info[0], |
193 | invocant => $info[1] || undef, |
194 | _positional_required => [split ' ', $info[2]], |
195 | _positional_optional => [split ' ', $info[3]], |
196 | _named_required => [split ' ', $info[4]], |
197 | _named_optional => [split ' ', $info[5]], |
198 | slurpy => $info[6] || undef, |
199 | ) |
200 | } |
201 | |
125c067e |
202 | 'ok' |
7a63380c |
203 | |
204 | __END__ |
205 | |
f2541b7d |
206 | =encoding UTF-8 |
207 | |
7a63380c |
208 | =head1 NAME |
209 | |
210 | Function::Parameters - subroutine definitions with parameter lists |
211 | |
212 | =head1 SYNOPSIS |
213 | |
81203272 |
214 | use Function::Parameters qw(:strict); |
7a63380c |
215 | |
698e861c |
216 | # simple function |
7a63380c |
217 | fun foo($bar, $baz) { |
218 | return $bar + $baz; |
219 | } |
220 | |
698e861c |
221 | # function with prototype |
d71d548b |
222 | fun mymap($fun, @args) |
223 | :(&@) |
224 | { |
7a63380c |
225 | my @res; |
226 | for (@args) { |
227 | push @res, $fun->($_); |
228 | } |
229 | @res |
230 | } |
231 | |
232 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
125c067e |
233 | |
698e861c |
234 | # method with implicit $self |
125c067e |
235 | method set_name($name) { |
236 | $self->{name} = $name; |
237 | } |
d8e5d540 |
238 | |
239 | # method with explicit invocant |
240 | method new($class: %init) { |
241 | return bless { %init }, $class; |
242 | } |
243 | |
81203272 |
244 | # function with optional parameters |
698e861c |
245 | fun search($haystack, $needle = qr/^(?!)/, $offset = 0) { |
246 | ... |
247 | } |
d8e5d540 |
248 | |
81203272 |
249 | # method with named parameters |
250 | method resize(:$width, :$height) { |
251 | $self->{width} = $width; |
252 | $self->{height} = $height; |
698e861c |
253 | } |
8dbfd12d |
254 | |
81203272 |
255 | $obj->resize(height => 4, width => 5); |
8dbfd12d |
256 | |
81203272 |
257 | # function with named optional parameters |
258 | fun search($haystack, :$needle = qr/^(?!)/, :$offset = 0) { |
259 | ... |
260 | } |
8dbfd12d |
261 | |
81203272 |
262 | my $results = search $text, offset => 200; |
8dbfd12d |
263 | |
81203272 |
264 | =head1 DESCRIPTION |
8dbfd12d |
265 | |
81203272 |
266 | This module extends Perl with keywords that let you define functions with |
267 | parameter lists. It uses Perl's L<keyword plugin|perlapi/PL_keyword_plugin> |
268 | API, so it works reliably and doesn't require a source filter. |
269 | |
270 | =head2 Basics |
271 | |
272 | The anatomy of a function (as recognized by this module): |
273 | |
274 | =over |
8dbfd12d |
275 | |
81203272 |
276 | =item 1. |
277 | |
278 | The keyword introducing the function. |
279 | |
280 | =item 2. |
281 | |
282 | The function name (optional). |
283 | |
284 | =item 3. |
285 | |
286 | The parameter list (optional). |
287 | |
288 | =item 4. |
289 | |
290 | The prototype (optional). |
291 | |
292 | =item 5. |
293 | |
294 | The attribute list (optional). |
295 | |
296 | =item 6. |
297 | |
298 | The function body. |
299 | |
300 | =back |
301 | |
302 | Example: |
303 | |
304 | # (1) (2) (3) (4) (5) (6) |
305 | fun foo ($x, $y) :($$) :lvalue { ... } |
c9a39f6b |
306 | |
81203272 |
307 | # (1) (6) |
308 | my $f = fun { ... }; |
125c067e |
309 | |
81203272 |
310 | In the following section I'm going to describe all parts in order from simplest to most complex. |
7a63380c |
311 | |
81203272 |
312 | =head3 Body |
7a63380c |
313 | |
81203272 |
314 | This is just a normal block of statements, as with L<C<sub>|perlsub>. No surprises here. |
7a63380c |
315 | |
81203272 |
316 | =head3 Name |
7a63380c |
317 | |
81203272 |
318 | If present, it specifies the name of the function being defined. As with |
319 | L<C<sub>|perlsub>, if a name is present, the whole declaration is syntactically |
320 | a statement and its effects are performed at compile time (i.e. at runtime you |
321 | can call functions whose definitions only occur later in the file). If no name |
322 | is present, the declaration is an expression that evaluates to a reference to |
323 | the function in question. No surprises here either. |
7a63380c |
324 | |
81203272 |
325 | =head3 Attributes |
7a63380c |
326 | |
81203272 |
327 | Attributes are relatively unusual in Perl code, but if you want them, they work |
328 | exactly the same as with L<C<sub>|perlsub/Subroutine-Attributes>. |
c9a39f6b |
329 | |
81203272 |
330 | =head3 Prototype |
698e861c |
331 | |
81203272 |
332 | As with L<C<sub>|perlsub/Prototypes>, a prototype, if present, contains hints as to how |
333 | the compiler should parse calls to this function. This means prototypes have no |
334 | effect if the function call is compiled before the function declaration has |
335 | been seen by the compiler or if the function to call is only determined at |
336 | runtime (e.g. because it's called as a method or through a reference). |
698e861c |
337 | |
81203272 |
338 | With L<C<sub>|perlsub>, a prototype comes directly after the function name (if |
339 | any). C<Function::Parameters> reserves this spot for the |
340 | L<parameter list|/"Parameter list">. To specify a prototype, put it as the |
341 | first attribute (e.g. C<fun foo :(&$$)>). This is syntactically unambiguous |
342 | because normal L<attributes|/Attributes> need a name after the colon. |
7a63380c |
343 | |
81203272 |
344 | =head3 Parameter list |
125c067e |
345 | |
81203272 |
346 | The parameter list is a list of variables enclosed in parentheses, except it's |
347 | actually a bit more complicated than that. A parameter list can include the |
348 | following 6 parts, all of which are optional: |
125c067e |
349 | |
81203272 |
350 | =over |
125c067e |
351 | |
81203272 |
352 | =item 1. Invocant |
125c067e |
353 | |
81203272 |
354 | This is a scalar variable followed by a colon (C<:>) and no comma. If an |
355 | invocant is present in the parameter list, the first element of |
356 | L<C<@_>|perlvar/@ARG> is automatically L<C<shift>ed|perlfunc/shift> off and |
357 | placed in this variable. This is intended for methods: |
125c067e |
358 | |
81203272 |
359 | method new($class: %init) { |
360 | return bless { %init }, $class; |
361 | } |
362 | |
363 | method throw($self:) { |
364 | die $self; |
365 | } |
125c067e |
366 | |
81203272 |
367 | =item 2. Required positional parameters |
fcaf7811 |
368 | |
81203272 |
369 | The most common kind of parameter. This is simply a comma-separated list of |
370 | scalars, which are filled from left to right with the arguments that the caller |
371 | passed in: |
fcaf7811 |
372 | |
81203272 |
373 | fun add($x, $y) { |
374 | return $x + $y; |
375 | } |
376 | |
377 | say add(2, 3); # "5" |
378 | |
379 | =item 3. Optional positional parameters |
380 | |
381 | Parameters can be marked as optional by putting an equals sign (C<=>) and an |
382 | expression (the "default argument") after them. If no corresponding argument is |
383 | passed in by the caller, the default argument will be used to initialize the |
384 | parameter: |
385 | |
386 | fun scale($base, $factor = 2) { |
387 | return $base * $factor; |
388 | } |
389 | |
390 | say scale(3, 5); # "15" |
391 | say scale(3); # "6" |
392 | |
393 | The default argument is I<not> cached. Every time a function is called with |
394 | some optional arguments missing, the corresponding default arguments are |
395 | evaluated from left to right. This makes no difference for a value like C<2> |
396 | but it is important for expressions with side effects, such as reference |
397 | constructors (C<[]>, C<{}>) or function calls. |
398 | |
399 | Default arguments see not only the surrounding lexical scope of their function |
400 | but also any preceding parameters. This allows the creation of dynamic defaults |
401 | based on previous arguments: |
402 | |
403 | method set_name($self: $nick = $self->default_nick, $real_name = $nick) { |
404 | $self->{nick} = $nick; |
405 | $self->{real_name} = $real_name; |
406 | } |
407 | |
408 | $obj->set_name("simplicio"); # same as: $obj->set_name("simplicio", "simplicio"); |
63a24d7c |
409 | |
81203272 |
410 | Because default arguments are actually evaluated as part of the function body, |
411 | you can also do silly things like this: |
412 | |
413 | fun foo($n = return "nope") { |
414 | "you gave me $n" |
415 | } |
416 | |
417 | say foo(2 + 2); # "you gave me 4" |
418 | say foo(); # "nope" |
419 | |
420 | =item 4. Required named parameters |
421 | |
422 | By putting a colon (C<:>) in front of a parameter you can make it named |
423 | instead of positional: |
424 | |
425 | fun rectangle(:$width, :$height) { |
426 | ... |
427 | } |
428 | |
429 | rectangle(width => 2, height => 5); |
430 | rectangle(height => 5, width => 2); # same thing! |
431 | |
432 | That is, the caller must specify a key name in addition to the value, but in |
433 | exchange the order of the arguments doesn't matter anymore. As with hash |
434 | initialization, you can specify the same key multiple times and the last |
435 | occurrence wins: |
436 | |
437 | rectangle(height => 1, width => 2, height => 2, height => 5; |
438 | # same as: rectangle(width => 2, height => 5); |
439 | |
440 | You can combine positional and named parameters as long as the positional |
441 | parameters come first: |
442 | |
443 | fun named_rectangle($name, :$width, :$height) { |
444 | ... |
445 | } |
446 | |
447 | named_rectangle("Avocado", width => 0.5, height => 1.2); |
448 | |
449 | =item 5. Optional named parameters |
450 | |
451 | As with positional parameters, you can make named parameters optional by |
452 | specifying a default argument after an equals sign (C<=>): |
453 | |
454 | fun rectangle(:$width, :$height, :$color = "chartreuse") { |
455 | ... |
456 | } |
457 | |
458 | rectangle(height => 10, width => 5); |
459 | # same as: rectangle(height => 10, width => 5, color => "chartreuse"); |
125c067e |
460 | |
461 | =cut |
462 | |
463 | =pod |
81203272 |
464 | |
465 | fun get($url, :$cookie_jar = HTTP::Cookies->new(), :$referrer = $url) { |
466 | ... |
467 | } |
125c067e |
468 | |
81203272 |
469 | my $data = get "http://www.example.com/", referrer => undef; # overrides $referrer = $url |
125c067e |
470 | |
81203272 |
471 | The above example shows that passing any value (even C<undef>) will override |
472 | the default argument. |
63a24d7c |
473 | |
81203272 |
474 | =item 6. Slurpy parameter |
ce052c57 |
475 | |
81203272 |
476 | Finally you can put an array or hash in the parameter list, which will gobble |
477 | up the remaining arguments (if any): |
ce052c57 |
478 | |
81203272 |
479 | fun foo($x, $y, @rest) { ... } |
480 | |
481 | foo "a", "b"; # $x = "a", $y = "b", @rest = () |
482 | foo "a", "b", "c"; # $x = "a", $y = "b", @rest = ("c") |
483 | foo "a", "b", "c", "d"; # $x = "a", $y = "b", @rest = ("c", "d") |
ce052c57 |
484 | |
81203272 |
485 | If you combine this with named parameters, the slurpy parameter will end up |
486 | containing all unrecognized keys: |
ce052c57 |
487 | |
81203272 |
488 | fun bar(:$size, @whatev) { ... } |
489 | |
490 | bar weight => 20, size => 2, location => [0, -3]; |
491 | # $size = 2, @whatev = ('weight', 20, 'location', [0, -3]) |
ce052c57 |
492 | |
81203272 |
493 | =back |
ce052c57 |
494 | |
81203272 |
495 | Apart from the L<C<shift>|perlfunc/shift> performed by the L<invocant|/"1. |
496 | Invocant">, all of the above leave L<C<@_>|perlvar/@ARG> unchanged; and if you |
497 | don't specify a parameter list at all, L<C<@_>|perlvar/@ARG> is all you get. |
d8e5d540 |
498 | |
81203272 |
499 | =head3 Keyword |
d8e5d540 |
500 | |
81203272 |
501 | The keywords provided by C<Function::Parameters> are customizable. Since |
502 | C<Function::Parameters> is actually a L<pragma|perlpragma>, the provided |
503 | keywords have lexical scope. The following import variants can be used: |
d8e5d540 |
504 | |
81203272 |
505 | =over |
273c6544 |
506 | |
81203272 |
507 | =item C<use Function::Parameters ':strict'> |
273c6544 |
508 | |
81203272 |
509 | Provides the keywords C<fun> and C<method> (described below) and enables |
510 | argument checks so that calling a function and omitting a required argument (or |
511 | passing too many arguments) will throw an error. |
273c6544 |
512 | |
81203272 |
513 | =item C<use Function::Parameters> |
273c6544 |
514 | |
81203272 |
515 | Provides the keywords C<fun> and C<method> (described below) and enables |
516 | "lax" mode: Omitting a required argument sets it to C<undef> while excess |
517 | arguments are silently ignored. |
273c6544 |
518 | |
81203272 |
519 | =item C<< use Function::Parameters { KEYWORD1 => TYPE1, KEYWORD2 => TYPE2, ... } >> |
698e861c |
520 | |
81203272 |
521 | Provides completely custom keywords as described by their types. A "type" is |
522 | either a string (one of the predefined types C<function>, C<method>, |
523 | C<classmethod>, C<function_strict>, C<method_strict>, C<classmethod_strict>) or |
524 | a reference to a hash with the following keys: |
698e861c |
525 | |
81203272 |
526 | =over |
698e861c |
527 | |
81203272 |
528 | =item C<name> |
698e861c |
529 | |
81203272 |
530 | Valid values: C<optional> (default), C<required> (all functions defined with |
531 | this keyword must have a name), and C<prohibited> (functions defined with this |
532 | keyword must be anonymous). |
698e861c |
533 | |
81203272 |
534 | =item C<shift> |
698e861c |
535 | |
81203272 |
536 | Valid values: strings that look like scalar variables. This lets you specify a |
537 | default L<invocant|/"1. Invocant">, i.e. a function defined with this keyword |
538 | that doesn't have an explicit invocant in its parameter list will automatically |
539 | L<C<shift>|perlfunc/shift> its first argument into the variable specified here. |
698e861c |
540 | |
81203272 |
541 | =item C<invocant> |
698e861c |
542 | |
81203272 |
543 | Valid values: booleans. If you set this to a true value, the keyword will |
544 | accept L<invocants|/"1. Invocant"> in parameter lists; otherwise specifying |
545 | an invocant in a function defined with this keyword is a syntax error. |
698e861c |
546 | |
81203272 |
547 | =item C<attributes> |
698e861c |
548 | |
81203272 |
549 | Valid values: strings containing (source code for) attributes. This causes any |
550 | function defined with this keyword to have the specified |
551 | L<attributes|attributes> (in addition to any attributes specified in the |
552 | function definition itself). |
698e861c |
553 | |
81203272 |
554 | =item C<default_arguments> |
698e861c |
555 | |
81203272 |
556 | Valid values: booleans. This property is on by default; use |
557 | C<< default_arguments => 0 >> to turn it off. This controls whether optional |
558 | parameters are allowed. If it is turned off, using C<=> in parameter lists is |
559 | a syntax error. |
698e861c |
560 | |
81203272 |
561 | =item C<check_argument_count> |
698e861c |
562 | |
81203272 |
563 | Valid values: booleans. If turned on, functions defined with this keyword will |
564 | automatically check that they have been passed all required arguments and no |
565 | excess arguments. If this check fails, an exception will by thrown via |
566 | L<C<Carp::croak>|Carp>. |
698e861c |
567 | |
ce052c57 |
568 | =back |
569 | |
81203272 |
570 | The predefined type C<function> is equivalent to: |
698e861c |
571 | |
572 | { |
573 | name => 'optional', |
81203272 |
574 | invocant => 0, |
698e861c |
575 | default_arguments => 1, |
576 | check_argument_count => 0, |
577 | } |
578 | |
81203272 |
579 | These are all default values, so C<function> is also equivalent to C<{}>. |
698e861c |
580 | |
81203272 |
581 | C<method> is equivalent to: |
698e861c |
582 | |
583 | { |
584 | name => 'optional', |
698e861c |
585 | shift => '$self', |
d8e5d540 |
586 | invocant => 1, |
81203272 |
587 | attributes => ':method', |
588 | default_arguments => 1, |
589 | check_argument_count => 0, |
698e861c |
590 | } |
591 | |
7817d698 |
592 | |
81203272 |
593 | C<classmethod> is equivalent to: |
698e861c |
594 | |
595 | { |
596 | name => 'optional', |
698e861c |
597 | shift => '$class', |
d8e5d540 |
598 | invocant => 1, |
81203272 |
599 | attributes => ':method', |
600 | default_arguments => 1, |
601 | check_argument_count => 0, |
698e861c |
602 | } |
ce052c57 |
603 | |
81203272 |
604 | C<function_strict>, C<method_strict>, and |
605 | C<classmethod_strict> are like C<function>, C<method>, and |
606 | C<classmethod>, respectively, but with C<< check_argument_count => 1 >>. |
63a24d7c |
607 | |
81203272 |
608 | =back |
63a24d7c |
609 | |
81203272 |
610 | Plain C<use Function::Parameters> is equivalent to |
611 | C<< use Function::Parameters { fun => 'function', method => 'method' } >>. |
63a24d7c |
612 | |
81203272 |
613 | C<use Function::Parameters qw(:strict)> is equivalent to |
614 | C<< use Function::Parameters { fun => 'function_strict', method => 'method_strict' } >>. |
63a24d7c |
615 | |
ebdc721b |
616 | =head2 Introspection |
617 | |
618 | You can ask a function at runtime what parameters it has. This functionality is |
619 | available through the function C<Function::Parameters::info> (which is not |
620 | exported, so you have to call it by its full name). It takes a reference to a |
621 | function, and returns either C<undef> (if it knows nothing about the function) |
622 | or a L<Function::Parameters::Info> object describing the parameter list. |
623 | |
624 | See L<Function::Parameters::Info> for examples. |
625 | |
81203272 |
626 | =head2 Wrapping C<Function::Parameters> |
125c067e |
627 | |
81203272 |
628 | If you want to write a wrapper around C<Function::Parameters>, you only have to |
629 | call its C<import> method. Due to its L<pragma|perlpragma> nature it always |
630 | affects the file that is currently being compiled. |
63a24d7c |
631 | |
632 | package Some::Wrapper; |
633 | use Function::Parameters (); |
634 | sub import { |
635 | Function::Parameters->import; |
698e861c |
636 | # or Function::Parameters->import(@custom_import_args); |
63a24d7c |
637 | } |
eeb7df5f |
638 | |
81203272 |
639 | =head2 How it works |
640 | |
641 | The module is actually written in L<C|perlxs> and uses |
642 | L<C<PL_keyword_plugin>|perlapi/PL_keyword_plugin> to generate opcodes directly. |
643 | However, you can run L<C<perl -MO=Deparse ...>|B::Deparse> on your code to see |
644 | what happens under the hood. In the simplest case (no argument checks, possibly |
645 | an L<invocant|/"1. Invocant">, required positional/slurpy parameters only), the |
646 | generated code corresponds to: |
647 | |
648 | fun foo($x, $y, @z) { ... } |
649 | # ... turns into ... |
650 | sub foo { my ($x, $y, @z) = @_; sub foo; ... } |
651 | |
652 | method bar($x, $y, @z) { ... } |
653 | # ... turns into ... |
654 | sub bar :method { my $self = shift; my ($x, $y, @z) = @_; sub bar; ... } |
655 | |
ebdc721b |
656 | =head1 SEE ALSO |
657 | |
658 | L<Function::Parameters::Info> |
659 | |
7a63380c |
660 | =head1 AUTHOR |
661 | |
662 | Lukas Mai, C<< <l.mai at web.de> >> |
663 | |
664 | =head1 COPYRIGHT & LICENSE |
665 | |
db81d362 |
666 | Copyright 2010, 2011, 2012 Lukas Mai. |
7a63380c |
667 | |
668 | This program is free software; you can redistribute it and/or modify it |
669 | under the terms of either: the GNU General Public License as published |
670 | by the Free Software Foundation; or the Artistic License. |
671 | |
672 | See http://dev.perl.org/licenses/ for more information. |
673 | |
674 | =cut |