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 { |
096dbcec |
11 | our $VERSION = '1.0003'; |
db81d362 |
12 | XSLoader::load; |
7a63380c |
13 | } |
14 | |
2d5cf47a |
15 | sub _assert_valid_identifier { |
16 | my ($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{"$attrs" doesn't look like valid attributes}; |
26 | } |
27 | |
125c067e |
28 | my @bare_arms = qw(function method); |
2d5cf47a |
29 | my %type_map = ( |
63915d26 |
30 | function => { |
31 | name => 'optional', |
32 | default_arguments => 1, |
33 | check_argument_count => 0, |
e158cf8f |
34 | named_parameters => 1, |
51a483f8 |
35 | types => 1, |
63915d26 |
36 | }, |
7947f7ce |
37 | method => { |
38 | name => 'optional', |
63915d26 |
39 | default_arguments => 1, |
40 | check_argument_count => 0, |
e158cf8f |
41 | named_parameters => 1, |
51a483f8 |
42 | types => 1, |
7947f7ce |
43 | attrs => ':method', |
63915d26 |
44 | shift => '$self', |
d8e5d540 |
45 | invocant => 1, |
7947f7ce |
46 | }, |
a23979e1 |
47 | classmethod => { |
48 | name => 'optional', |
63915d26 |
49 | default_arguments => 1, |
50 | check_argument_count => 0, |
e158cf8f |
51 | named_parameters => 1, |
51a483f8 |
52 | types => 1, |
698e861c |
53 | attributes => ':method', |
63915d26 |
54 | shift => '$class', |
d8e5d540 |
55 | invocant => 1, |
a23979e1 |
56 | }, |
2d5cf47a |
57 | ); |
7817d698 |
58 | for my $k (keys %type_map) { |
59 | $type_map{$k . '_strict'} = { |
60 | %{$type_map{$k}}, |
61 | check_argument_count => 1, |
62 | }; |
63 | } |
c9a39f6b |
64 | |
db81d362 |
65 | sub import { |
66 | my $class = shift; |
7a63380c |
67 | |
fcaf7811 |
68 | if (!@_) { |
69 | @_ = { |
70 | fun => 'function', |
71 | method => 'method', |
72 | }; |
73 | } |
74 | if (@_ == 1 && $_[0] eq ':strict') { |
75 | @_ = { |
76 | fun => 'function_strict', |
77 | method => 'method_strict', |
78 | }; |
79 | } |
125c067e |
80 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
fcaf7811 |
81 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]}; |
125c067e |
82 | } |
7a63380c |
83 | |
125c067e |
84 | my %spec; |
85 | |
86 | my $bare = 0; |
87 | for my $proto (@_) { |
88 | my $item = ref $proto |
89 | ? $proto |
90 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
91 | ; |
ae6e00b5 |
92 | my ($name, $proto_type) = @$item; |
2d5cf47a |
93 | _assert_valid_identifier $name; |
94 | |
ae6e00b5 |
95 | unless (ref $proto_type) { |
96 | # use '||' instead of 'or' to preserve $proto_type in the error message |
97 | $proto_type = $type_map{$proto_type} |
98 | || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
2d5cf47a |
99 | } |
b72eb6ee |
100 | |
ae6e00b5 |
101 | my %type = %$proto_type; |
102 | my %clean; |
10acc8b1 |
103 | |
ae6e00b5 |
104 | $clean{name} = delete $type{name} || 'optional'; |
105 | $clean{name} =~ /^(?:optional|required|prohibited)\z/ |
106 | or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
10acc8b1 |
107 | |
ae6e00b5 |
108 | $clean{shift} = delete $type{shift} || ''; |
10acc8b1 |
109 | _assert_valid_identifier $clean{shift}, 1 if $clean{shift}; |
110 | |
698e861c |
111 | $clean{attrs} = join ' ', map delete $type{$_} || (), qw(attributes attrs); |
10acc8b1 |
112 | _assert_valid_attributes $clean{attrs} if $clean{attrs}; |
125c067e |
113 | |
59f51b8b |
114 | $clean{default_arguments} = |
115 | exists $type{default_arguments} |
116 | ? !!delete $type{default_arguments} |
117 | : 1 |
118 | ; |
63915d26 |
119 | $clean{check_argument_count} = !!delete $type{check_argument_count}; |
d8e5d540 |
120 | $clean{invocant} = !!delete $type{invocant}; |
e158cf8f |
121 | $clean{named_parameters} = !!delete $type{named_parameters}; |
51a483f8 |
122 | $clean{types} = !!delete $type{types}; |
63915d26 |
123 | |
ae6e00b5 |
124 | %type and confess "Invalid keyword property: @{[keys %type]}"; |
125 | |
126 | $spec{$name} = \%clean; |
125c067e |
127 | } |
128 | |
db81d362 |
129 | for my $kw (keys %spec) { |
130 | my $type = $spec{$kw}; |
131 | |
63915d26 |
132 | my $flags = |
133 | $type->{name} eq 'prohibited' ? FLAG_ANON_OK : |
134 | $type->{name} eq 'required' ? FLAG_NAME_OK : |
135 | FLAG_ANON_OK | FLAG_NAME_OK |
136 | ; |
137 | $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments}; |
51a483f8 |
138 | $flags |= FLAG_CHECK_NARGS | FLAG_CHECK_TARGS if $type->{check_argument_count}; |
d8e5d540 |
139 | $flags |= FLAG_INVOCANT if $type->{invocant}; |
e158cf8f |
140 | $flags |= FLAG_NAMED_PARAMS if $type->{named_parameters}; |
51a483f8 |
141 | $flags |= FLAG_TYPES_OK if $type->{types}; |
63915d26 |
142 | $^H{HINTK_FLAGS_ . $kw} = $flags; |
ae6e00b5 |
143 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift}; |
10acc8b1 |
144 | $^H{HINTK_ATTRS_ . $kw} = $type->{attrs}; |
db81d362 |
145 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
125c067e |
146 | } |
eeb7df5f |
147 | } |
148 | |
db81d362 |
149 | sub unimport { |
eeb7df5f |
150 | my $class = shift; |
125c067e |
151 | |
db81d362 |
152 | if (!@_) { |
153 | delete $^H{+HINTK_KEYWORDS}; |
125c067e |
154 | return; |
155 | } |
156 | |
db81d362 |
157 | for my $kw (@_) { |
158 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
125c067e |
159 | } |
160 | } |
161 | |
db81d362 |
162 | |
53c979f0 |
163 | our %metadata; |
164 | |
165 | sub _register_info { |
166 | my ( |
167 | $key, |
168 | $declarator, |
169 | $invocant, |
51a483f8 |
170 | $invocant_type, |
53c979f0 |
171 | $positional_required, |
172 | $positional_optional, |
173 | $named_required, |
174 | $named_optional, |
175 | $slurpy, |
51a483f8 |
176 | $slurpy_type, |
53c979f0 |
177 | ) = @_; |
178 | |
51a483f8 |
179 | my $info = { |
180 | declarator => $declarator, |
181 | invocant => defined $invocant ? [$invocant, $invocant_type] : undef, |
182 | slurpy => defined $slurpy ? [$slurpy , $slurpy_type ] : undef, |
183 | positional_required => $positional_required, |
184 | positional_optional => $positional_optional, |
185 | named_required => $named_required, |
186 | named_optional => $named_optional, |
187 | }; |
188 | |
189 | $metadata{$key} = $info; |
190 | } |
191 | |
192 | sub _mkparam1 { |
193 | my ($pair) = @_; |
194 | my ($v, $t) = @{$pair || []} or return undef; |
195 | Function::Parameters::Param->new( |
196 | name => $v, |
197 | type => $t, |
198 | ) |
199 | } |
200 | |
201 | sub _mkparams { |
202 | my @r; |
203 | while (my ($v, $t) = splice @_, 0, 2) { |
204 | push @r, Function::Parameters::Param->new( |
205 | name => $v, |
206 | type => $t, |
207 | ); |
208 | } |
209 | \@r |
53c979f0 |
210 | } |
211 | |
212 | sub info { |
213 | my ($func) = @_; |
214 | my $key = _cv_root $func or return undef; |
51a483f8 |
215 | my $info = $metadata{$key} or return undef; |
53c979f0 |
216 | require Function::Parameters::Info; |
217 | Function::Parameters::Info->new( |
51a483f8 |
218 | keyword => $info->{declarator}, |
219 | invocant => _mkparam1($info->{invocant}), |
220 | slurpy => _mkparam1($info->{slurpy}), |
221 | (map +("_$_" => _mkparams @{$info->{$_}}), glob '{positional,named}_{required,optional}') |
53c979f0 |
222 | ) |
223 | } |
224 | |
125c067e |
225 | 'ok' |
7a63380c |
226 | |
227 | __END__ |
228 | |
f2541b7d |
229 | =encoding UTF-8 |
230 | |
7a63380c |
231 | =head1 NAME |
232 | |
233 | Function::Parameters - subroutine definitions with parameter lists |
234 | |
235 | =head1 SYNOPSIS |
236 | |
81203272 |
237 | use Function::Parameters qw(:strict); |
7a63380c |
238 | |
698e861c |
239 | # simple function |
7a63380c |
240 | fun foo($bar, $baz) { |
241 | return $bar + $baz; |
242 | } |
243 | |
698e861c |
244 | # function with prototype |
d71d548b |
245 | fun mymap($fun, @args) |
246 | :(&@) |
247 | { |
7a63380c |
248 | my @res; |
249 | for (@args) { |
250 | push @res, $fun->($_); |
251 | } |
252 | @res |
253 | } |
254 | |
255 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
125c067e |
256 | |
698e861c |
257 | # method with implicit $self |
125c067e |
258 | method set_name($name) { |
259 | $self->{name} = $name; |
260 | } |
d8e5d540 |
261 | |
262 | # method with explicit invocant |
263 | method new($class: %init) { |
264 | return bless { %init }, $class; |
265 | } |
266 | |
81203272 |
267 | # function with optional parameters |
698e861c |
268 | fun search($haystack, $needle = qr/^(?!)/, $offset = 0) { |
269 | ... |
270 | } |
d8e5d540 |
271 | |
81203272 |
272 | # method with named parameters |
273 | method resize(:$width, :$height) { |
274 | $self->{width} = $width; |
275 | $self->{height} = $height; |
698e861c |
276 | } |
8dbfd12d |
277 | |
81203272 |
278 | $obj->resize(height => 4, width => 5); |
8dbfd12d |
279 | |
81203272 |
280 | # function with named optional parameters |
281 | fun search($haystack, :$needle = qr/^(?!)/, :$offset = 0) { |
282 | ... |
283 | } |
8dbfd12d |
284 | |
81203272 |
285 | my $results = search $text, offset => 200; |
8dbfd12d |
286 | |
81203272 |
287 | =head1 DESCRIPTION |
8dbfd12d |
288 | |
81203272 |
289 | This module extends Perl with keywords that let you define functions with |
290 | parameter lists. It uses Perl's L<keyword plugin|perlapi/PL_keyword_plugin> |
291 | API, so it works reliably and doesn't require a source filter. |
292 | |
293 | =head2 Basics |
294 | |
295 | The anatomy of a function (as recognized by this module): |
296 | |
297 | =over |
8dbfd12d |
298 | |
81203272 |
299 | =item 1. |
300 | |
301 | The keyword introducing the function. |
302 | |
303 | =item 2. |
304 | |
305 | The function name (optional). |
306 | |
307 | =item 3. |
308 | |
309 | The parameter list (optional). |
310 | |
311 | =item 4. |
312 | |
313 | The prototype (optional). |
314 | |
315 | =item 5. |
316 | |
317 | The attribute list (optional). |
318 | |
319 | =item 6. |
320 | |
321 | The function body. |
322 | |
323 | =back |
324 | |
325 | Example: |
326 | |
327 | # (1) (2) (3) (4) (5) (6) |
328 | fun foo ($x, $y) :($$) :lvalue { ... } |
c9a39f6b |
329 | |
81203272 |
330 | # (1) (6) |
331 | my $f = fun { ... }; |
125c067e |
332 | |
81203272 |
333 | In the following section I'm going to describe all parts in order from simplest to most complex. |
7a63380c |
334 | |
81203272 |
335 | =head3 Body |
7a63380c |
336 | |
81203272 |
337 | This is just a normal block of statements, as with L<C<sub>|perlsub>. No surprises here. |
7a63380c |
338 | |
81203272 |
339 | =head3 Name |
7a63380c |
340 | |
81203272 |
341 | If present, it specifies the name of the function being defined. As with |
342 | L<C<sub>|perlsub>, if a name is present, the whole declaration is syntactically |
343 | a statement and its effects are performed at compile time (i.e. at runtime you |
344 | can call functions whose definitions only occur later in the file). If no name |
345 | is present, the declaration is an expression that evaluates to a reference to |
346 | the function in question. No surprises here either. |
7a63380c |
347 | |
81203272 |
348 | =head3 Attributes |
7a63380c |
349 | |
81203272 |
350 | Attributes are relatively unusual in Perl code, but if you want them, they work |
351 | exactly the same as with L<C<sub>|perlsub/Subroutine-Attributes>. |
c9a39f6b |
352 | |
81203272 |
353 | =head3 Prototype |
698e861c |
354 | |
81203272 |
355 | As with L<C<sub>|perlsub/Prototypes>, a prototype, if present, contains hints as to how |
356 | the compiler should parse calls to this function. This means prototypes have no |
357 | effect if the function call is compiled before the function declaration has |
358 | been seen by the compiler or if the function to call is only determined at |
359 | runtime (e.g. because it's called as a method or through a reference). |
698e861c |
360 | |
81203272 |
361 | With L<C<sub>|perlsub>, a prototype comes directly after the function name (if |
362 | any). C<Function::Parameters> reserves this spot for the |
363 | L<parameter list|/"Parameter list">. To specify a prototype, put it as the |
364 | first attribute (e.g. C<fun foo :(&$$)>). This is syntactically unambiguous |
365 | because normal L<attributes|/Attributes> need a name after the colon. |
7a63380c |
366 | |
81203272 |
367 | =head3 Parameter list |
125c067e |
368 | |
81203272 |
369 | The parameter list is a list of variables enclosed in parentheses, except it's |
370 | actually a bit more complicated than that. A parameter list can include the |
371 | following 6 parts, all of which are optional: |
125c067e |
372 | |
81203272 |
373 | =over |
125c067e |
374 | |
81203272 |
375 | =item 1. Invocant |
125c067e |
376 | |
81203272 |
377 | This is a scalar variable followed by a colon (C<:>) and no comma. If an |
378 | invocant is present in the parameter list, the first element of |
379 | L<C<@_>|perlvar/@ARG> is automatically L<C<shift>ed|perlfunc/shift> off and |
380 | placed in this variable. This is intended for methods: |
125c067e |
381 | |
81203272 |
382 | method new($class: %init) { |
383 | return bless { %init }, $class; |
384 | } |
385 | |
386 | method throw($self:) { |
387 | die $self; |
388 | } |
125c067e |
389 | |
81203272 |
390 | =item 2. Required positional parameters |
fcaf7811 |
391 | |
81203272 |
392 | The most common kind of parameter. This is simply a comma-separated list of |
393 | scalars, which are filled from left to right with the arguments that the caller |
394 | passed in: |
fcaf7811 |
395 | |
81203272 |
396 | fun add($x, $y) { |
397 | return $x + $y; |
398 | } |
399 | |
400 | say add(2, 3); # "5" |
401 | |
402 | =item 3. Optional positional parameters |
403 | |
404 | Parameters can be marked as optional by putting an equals sign (C<=>) and an |
405 | expression (the "default argument") after them. If no corresponding argument is |
406 | passed in by the caller, the default argument will be used to initialize the |
407 | parameter: |
408 | |
409 | fun scale($base, $factor = 2) { |
410 | return $base * $factor; |
411 | } |
412 | |
413 | say scale(3, 5); # "15" |
414 | say scale(3); # "6" |
415 | |
416 | The default argument is I<not> cached. Every time a function is called with |
417 | some optional arguments missing, the corresponding default arguments are |
418 | evaluated from left to right. This makes no difference for a value like C<2> |
419 | but it is important for expressions with side effects, such as reference |
420 | constructors (C<[]>, C<{}>) or function calls. |
421 | |
422 | Default arguments see not only the surrounding lexical scope of their function |
423 | but also any preceding parameters. This allows the creation of dynamic defaults |
424 | based on previous arguments: |
425 | |
426 | method set_name($self: $nick = $self->default_nick, $real_name = $nick) { |
427 | $self->{nick} = $nick; |
428 | $self->{real_name} = $real_name; |
429 | } |
430 | |
431 | $obj->set_name("simplicio"); # same as: $obj->set_name("simplicio", "simplicio"); |
63a24d7c |
432 | |
81203272 |
433 | Because default arguments are actually evaluated as part of the function body, |
434 | you can also do silly things like this: |
435 | |
436 | fun foo($n = return "nope") { |
437 | "you gave me $n" |
438 | } |
439 | |
440 | say foo(2 + 2); # "you gave me 4" |
441 | say foo(); # "nope" |
442 | |
443 | =item 4. Required named parameters |
444 | |
445 | By putting a colon (C<:>) in front of a parameter you can make it named |
446 | instead of positional: |
447 | |
448 | fun rectangle(:$width, :$height) { |
449 | ... |
450 | } |
451 | |
452 | rectangle(width => 2, height => 5); |
453 | rectangle(height => 5, width => 2); # same thing! |
454 | |
455 | That is, the caller must specify a key name in addition to the value, but in |
456 | exchange the order of the arguments doesn't matter anymore. As with hash |
457 | initialization, you can specify the same key multiple times and the last |
458 | occurrence wins: |
459 | |
460 | rectangle(height => 1, width => 2, height => 2, height => 5; |
461 | # same as: rectangle(width => 2, height => 5); |
462 | |
463 | You can combine positional and named parameters as long as the positional |
464 | parameters come first: |
465 | |
466 | fun named_rectangle($name, :$width, :$height) { |
467 | ... |
468 | } |
469 | |
470 | named_rectangle("Avocado", width => 0.5, height => 1.2); |
471 | |
472 | =item 5. Optional named parameters |
473 | |
474 | As with positional parameters, you can make named parameters optional by |
475 | specifying a default argument after an equals sign (C<=>): |
476 | |
477 | fun rectangle(:$width, :$height, :$color = "chartreuse") { |
478 | ... |
479 | } |
480 | |
481 | rectangle(height => 10, width => 5); |
482 | # same as: rectangle(height => 10, width => 5, color => "chartreuse"); |
125c067e |
483 | |
484 | =cut |
485 | |
486 | =pod |
81203272 |
487 | |
488 | fun get($url, :$cookie_jar = HTTP::Cookies->new(), :$referrer = $url) { |
489 | ... |
490 | } |
125c067e |
491 | |
81203272 |
492 | my $data = get "http://www.example.com/", referrer => undef; # overrides $referrer = $url |
125c067e |
493 | |
81203272 |
494 | The above example shows that passing any value (even C<undef>) will override |
495 | the default argument. |
63a24d7c |
496 | |
81203272 |
497 | =item 6. Slurpy parameter |
ce052c57 |
498 | |
81203272 |
499 | Finally you can put an array or hash in the parameter list, which will gobble |
500 | up the remaining arguments (if any): |
ce052c57 |
501 | |
81203272 |
502 | fun foo($x, $y, @rest) { ... } |
503 | |
504 | foo "a", "b"; # $x = "a", $y = "b", @rest = () |
505 | foo "a", "b", "c"; # $x = "a", $y = "b", @rest = ("c") |
506 | foo "a", "b", "c", "d"; # $x = "a", $y = "b", @rest = ("c", "d") |
ce052c57 |
507 | |
81203272 |
508 | If you combine this with named parameters, the slurpy parameter will end up |
509 | containing all unrecognized keys: |
ce052c57 |
510 | |
81203272 |
511 | fun bar(:$size, @whatev) { ... } |
512 | |
513 | bar weight => 20, size => 2, location => [0, -3]; |
514 | # $size = 2, @whatev = ('weight', 20, 'location', [0, -3]) |
ce052c57 |
515 | |
81203272 |
516 | =back |
ce052c57 |
517 | |
81203272 |
518 | Apart from the L<C<shift>|perlfunc/shift> performed by the L<invocant|/"1. |
519 | Invocant">, all of the above leave L<C<@_>|perlvar/@ARG> unchanged; and if you |
520 | don't specify a parameter list at all, L<C<@_>|perlvar/@ARG> is all you get. |
d8e5d540 |
521 | |
81203272 |
522 | =head3 Keyword |
d8e5d540 |
523 | |
81203272 |
524 | The keywords provided by C<Function::Parameters> are customizable. Since |
525 | C<Function::Parameters> is actually a L<pragma|perlpragma>, the provided |
526 | keywords have lexical scope. The following import variants can be used: |
d8e5d540 |
527 | |
81203272 |
528 | =over |
273c6544 |
529 | |
81203272 |
530 | =item C<use Function::Parameters ':strict'> |
273c6544 |
531 | |
81203272 |
532 | Provides the keywords C<fun> and C<method> (described below) and enables |
533 | argument checks so that calling a function and omitting a required argument (or |
534 | passing too many arguments) will throw an error. |
273c6544 |
535 | |
81203272 |
536 | =item C<use Function::Parameters> |
273c6544 |
537 | |
81203272 |
538 | Provides the keywords C<fun> and C<method> (described below) and enables |
539 | "lax" mode: Omitting a required argument sets it to C<undef> while excess |
540 | arguments are silently ignored. |
273c6544 |
541 | |
81203272 |
542 | =item C<< use Function::Parameters { KEYWORD1 => TYPE1, KEYWORD2 => TYPE2, ... } >> |
698e861c |
543 | |
81203272 |
544 | Provides completely custom keywords as described by their types. A "type" is |
545 | either a string (one of the predefined types C<function>, C<method>, |
546 | C<classmethod>, C<function_strict>, C<method_strict>, C<classmethod_strict>) or |
547 | a reference to a hash with the following keys: |
698e861c |
548 | |
81203272 |
549 | =over |
698e861c |
550 | |
81203272 |
551 | =item C<name> |
698e861c |
552 | |
81203272 |
553 | Valid values: C<optional> (default), C<required> (all functions defined with |
554 | this keyword must have a name), and C<prohibited> (functions defined with this |
555 | keyword must be anonymous). |
698e861c |
556 | |
81203272 |
557 | =item C<shift> |
698e861c |
558 | |
81203272 |
559 | Valid values: strings that look like scalar variables. This lets you specify a |
560 | default L<invocant|/"1. Invocant">, i.e. a function defined with this keyword |
561 | that doesn't have an explicit invocant in its parameter list will automatically |
562 | L<C<shift>|perlfunc/shift> its first argument into the variable specified here. |
698e861c |
563 | |
81203272 |
564 | =item C<invocant> |
698e861c |
565 | |
81203272 |
566 | Valid values: booleans. If you set this to a true value, the keyword will |
567 | accept L<invocants|/"1. Invocant"> in parameter lists; otherwise specifying |
568 | an invocant in a function defined with this keyword is a syntax error. |
698e861c |
569 | |
81203272 |
570 | =item C<attributes> |
698e861c |
571 | |
81203272 |
572 | Valid values: strings containing (source code for) attributes. This causes any |
573 | function defined with this keyword to have the specified |
574 | L<attributes|attributes> (in addition to any attributes specified in the |
575 | function definition itself). |
698e861c |
576 | |
81203272 |
577 | =item C<default_arguments> |
698e861c |
578 | |
81203272 |
579 | Valid values: booleans. This property is on by default; use |
580 | C<< default_arguments => 0 >> to turn it off. This controls whether optional |
581 | parameters are allowed. If it is turned off, using C<=> in parameter lists is |
582 | a syntax error. |
698e861c |
583 | |
81203272 |
584 | =item C<check_argument_count> |
698e861c |
585 | |
81203272 |
586 | Valid values: booleans. If turned on, functions defined with this keyword will |
587 | automatically check that they have been passed all required arguments and no |
588 | excess arguments. If this check fails, an exception will by thrown via |
589 | L<C<Carp::croak>|Carp>. |
698e861c |
590 | |
ce052c57 |
591 | =back |
592 | |
81203272 |
593 | The predefined type C<function> is equivalent to: |
698e861c |
594 | |
595 | { |
596 | name => 'optional', |
81203272 |
597 | invocant => 0, |
698e861c |
598 | default_arguments => 1, |
599 | check_argument_count => 0, |
600 | } |
601 | |
81203272 |
602 | These are all default values, so C<function> is also equivalent to C<{}>. |
698e861c |
603 | |
81203272 |
604 | C<method> is equivalent to: |
698e861c |
605 | |
606 | { |
607 | name => 'optional', |
698e861c |
608 | shift => '$self', |
d8e5d540 |
609 | invocant => 1, |
81203272 |
610 | attributes => ':method', |
611 | default_arguments => 1, |
612 | check_argument_count => 0, |
698e861c |
613 | } |
614 | |
7817d698 |
615 | |
81203272 |
616 | C<classmethod> is equivalent to: |
698e861c |
617 | |
618 | { |
619 | name => 'optional', |
698e861c |
620 | shift => '$class', |
d8e5d540 |
621 | invocant => 1, |
81203272 |
622 | attributes => ':method', |
623 | default_arguments => 1, |
624 | check_argument_count => 0, |
698e861c |
625 | } |
ce052c57 |
626 | |
81203272 |
627 | C<function_strict>, C<method_strict>, and |
628 | C<classmethod_strict> are like C<function>, C<method>, and |
629 | C<classmethod>, respectively, but with C<< check_argument_count => 1 >>. |
63a24d7c |
630 | |
81203272 |
631 | =back |
63a24d7c |
632 | |
81203272 |
633 | Plain C<use Function::Parameters> is equivalent to |
634 | C<< use Function::Parameters { fun => 'function', method => 'method' } >>. |
63a24d7c |
635 | |
81203272 |
636 | C<use Function::Parameters qw(:strict)> is equivalent to |
637 | C<< use Function::Parameters { fun => 'function_strict', method => 'method_strict' } >>. |
63a24d7c |
638 | |
ebdc721b |
639 | =head2 Introspection |
640 | |
641 | You can ask a function at runtime what parameters it has. This functionality is |
642 | available through the function C<Function::Parameters::info> (which is not |
643 | exported, so you have to call it by its full name). It takes a reference to a |
644 | function, and returns either C<undef> (if it knows nothing about the function) |
645 | or a L<Function::Parameters::Info> object describing the parameter list. |
646 | |
af04c6f1 |
647 | Note: This feature is implemented using L<Moo>, so you'll need to have L<Moo> |
648 | installed if you want to call C<Function::Parameters::info>. |
649 | |
ebdc721b |
650 | See L<Function::Parameters::Info> for examples. |
651 | |
81203272 |
652 | =head2 Wrapping C<Function::Parameters> |
125c067e |
653 | |
81203272 |
654 | If you want to write a wrapper around C<Function::Parameters>, you only have to |
655 | call its C<import> method. Due to its L<pragma|perlpragma> nature it always |
656 | affects the file that is currently being compiled. |
63a24d7c |
657 | |
658 | package Some::Wrapper; |
659 | use Function::Parameters (); |
660 | sub import { |
661 | Function::Parameters->import; |
698e861c |
662 | # or Function::Parameters->import(@custom_import_args); |
63a24d7c |
663 | } |
eeb7df5f |
664 | |
0175ff9a |
665 | =head2 Experimental feature: Types |
666 | |
667 | An experimental feature is now available: You can annotate parameters with |
668 | L<Moose types|Moose::Manual::Types>. That is, before each parameter you can put |
669 | a type specification consisting of identifiers (C<Foo>), unions (C<... | ...>), |
670 | and parametric types (C<...[...]>). Example: |
671 | |
672 | fun foo(Int $n, ArrayRef[String | CodeRef] $cb) { ... } |
673 | |
674 | If you do this, L<Moose> will be loaded automatically (if that hasn't happened |
675 | yet). These specifications are parsed and validated using |
676 | L<C<Moose::Util::TypeConstraints::find_or_parse_type_constraint>|Moose::Util::TypeConstraints/find_or_parse_type_constraint>. |
677 | |
678 | If you are in "lax" mode, nothing further happens and the types are ignored. If |
679 | you are in "strict" mode, C<Function::Parameters> generates code to make sure |
680 | any values passed in conform to the type (via |
d54d249f |
681 | L<< C<< $constraint->check($value) >>|Moose::Meta::TypeConstraint/$constraint->check($value) >>). |
0175ff9a |
682 | |
683 | In addition, these type constraints are inspectable through the |
684 | L<Function::Parameters::Info> object returned by |
685 | L<C<Function::Parameters::info>|/Introspection>. |
686 | |
687 | =head2 Experimental experimental feature: Type expressions |
688 | |
689 | An even more experimental feature is the ability to specify arbitrary |
690 | expressions as types. The syntax for this is like the literal types described |
691 | above, but with an expression wrapped in parentheses (C<( EXPR )>). Example: |
692 | |
693 | fun foo(('Int') $n, ($othertype) $x) { ... } |
694 | |
695 | Every type expression must return either a string (which is resolved as for |
696 | literal types), or a L<type constraint object|Moose::Meta::TypeConstraint> |
697 | (providing C<check> and C<get_message> methods). |
698 | |
699 | Note that these expressions are evaluated (once) at parse time (similar to |
700 | C<BEGIN> blocks), so make sure that any variables you use are set and any |
701 | functions you call are defined at parse time. |
702 | |
81203272 |
703 | =head2 How it works |
704 | |
705 | The module is actually written in L<C|perlxs> and uses |
706 | L<C<PL_keyword_plugin>|perlapi/PL_keyword_plugin> to generate opcodes directly. |
707 | However, you can run L<C<perl -MO=Deparse ...>|B::Deparse> on your code to see |
708 | what happens under the hood. In the simplest case (no argument checks, possibly |
709 | an L<invocant|/"1. Invocant">, required positional/slurpy parameters only), the |
710 | generated code corresponds to: |
711 | |
712 | fun foo($x, $y, @z) { ... } |
713 | # ... turns into ... |
714 | sub foo { my ($x, $y, @z) = @_; sub foo; ... } |
715 | |
716 | method bar($x, $y, @z) { ... } |
717 | # ... turns into ... |
718 | sub bar :method { my $self = shift; my ($x, $y, @z) = @_; sub bar; ... } |
719 | |
0175ff9a |
720 | =head1 SUPPORT AND DOCUMENTATION |
721 | |
722 | After installing, you can find documentation for this module with the |
723 | perldoc command. |
724 | |
725 | perldoc Function::Parameters |
726 | |
727 | You can also look for information at: |
728 | |
729 | =over |
730 | |
731 | =item MetaCPAN |
732 | |
733 | L<https://metacpan.org/module/Function%3A%3AParameters> |
734 | |
735 | =item RT, CPAN's request tracker |
736 | |
737 | L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Function-Parameters> |
738 | |
739 | =item AnnoCPAN, Annotated CPAN documentation |
740 | |
741 | L<http://annocpan.org/dist/Function-Parameters> |
742 | |
743 | =item CPAN Ratings |
744 | |
745 | L<http://cpanratings.perl.org/d/Function-Parameters> |
746 | |
747 | =item Search CPAN |
748 | |
749 | L<http://search.cpan.org/dist/Function-Parameters/> |
750 | |
751 | =back |
752 | |
ebdc721b |
753 | =head1 SEE ALSO |
754 | |
755 | L<Function::Parameters::Info> |
756 | |
7a63380c |
757 | =head1 AUTHOR |
758 | |
759 | Lukas Mai, C<< <l.mai at web.de> >> |
760 | |
761 | =head1 COPYRIGHT & LICENSE |
762 | |
db81d362 |
763 | Copyright 2010, 2011, 2012 Lukas Mai. |
7a63380c |
764 | |
765 | This program is free software; you can redistribute it and/or modify it |
766 | under the terms of either: the GNU General Public License as published |
767 | by the Free Software Foundation; or the Artistic License. |
768 | |
769 | See http://dev.perl.org/licenses/ for more information. |
770 | |
771 | =cut |