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 { |
e85d37cf |
11 | our $VERSION = '1.00_02'; |
12 | our $XS_VERSION = $VERSION; |
13 | $VERSION = eval $VERSION; |
db81d362 |
14 | XSLoader::load; |
7a63380c |
15 | } |
16 | |
2d5cf47a |
17 | sub _assert_valid_identifier { |
18 | my ($name, $with_dollar) = @_; |
19 | my $bonus = $with_dollar ? '\$' : ''; |
20 | $name =~ /^${bonus}[^\W\d]\w*\z/ |
21 | or confess qq{"$name" doesn't look like a valid identifier}; |
22 | } |
23 | |
b72eb6ee |
24 | sub _assert_valid_attributes { |
25 | my ($attrs) = @_; |
26 | $attrs =~ /^\s*:\s*[^\W\d]\w*\s*(?:(?:\s|:\s*)[^\W\d]\w*\s*)*(?:\(|\z)/ |
27 | or confess qq{"$attrs" doesn't look like valid attributes}; |
28 | } |
29 | |
125c067e |
30 | my @bare_arms = qw(function method); |
2d5cf47a |
31 | my %type_map = ( |
63915d26 |
32 | function => { |
33 | name => 'optional', |
34 | default_arguments => 1, |
35 | check_argument_count => 0, |
e158cf8f |
36 | named_parameters => 1, |
51a483f8 |
37 | types => 1, |
63915d26 |
38 | }, |
7947f7ce |
39 | method => { |
40 | name => 'optional', |
63915d26 |
41 | default_arguments => 1, |
42 | check_argument_count => 0, |
e158cf8f |
43 | named_parameters => 1, |
51a483f8 |
44 | types => 1, |
7947f7ce |
45 | attrs => ':method', |
63915d26 |
46 | shift => '$self', |
d8e5d540 |
47 | invocant => 1, |
7947f7ce |
48 | }, |
a23979e1 |
49 | classmethod => { |
50 | name => 'optional', |
63915d26 |
51 | default_arguments => 1, |
52 | check_argument_count => 0, |
e158cf8f |
53 | named_parameters => 1, |
51a483f8 |
54 | types => 1, |
698e861c |
55 | attributes => ':method', |
63915d26 |
56 | shift => '$class', |
d8e5d540 |
57 | invocant => 1, |
a23979e1 |
58 | }, |
2d5cf47a |
59 | ); |
7817d698 |
60 | for my $k (keys %type_map) { |
61 | $type_map{$k . '_strict'} = { |
62 | %{$type_map{$k}}, |
63 | check_argument_count => 1, |
64 | }; |
65 | } |
c9a39f6b |
66 | |
db81d362 |
67 | sub import { |
68 | my $class = shift; |
7a63380c |
69 | |
fcaf7811 |
70 | if (!@_) { |
71 | @_ = { |
72 | fun => 'function', |
73 | method => 'method', |
74 | }; |
75 | } |
76 | if (@_ == 1 && $_[0] eq ':strict') { |
77 | @_ = { |
78 | fun => 'function_strict', |
79 | method => 'method_strict', |
80 | }; |
81 | } |
125c067e |
82 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
fcaf7811 |
83 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]}; |
125c067e |
84 | } |
7a63380c |
85 | |
125c067e |
86 | my %spec; |
87 | |
88 | my $bare = 0; |
89 | for my $proto (@_) { |
90 | my $item = ref $proto |
91 | ? $proto |
92 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
93 | ; |
ae6e00b5 |
94 | my ($name, $proto_type) = @$item; |
2d5cf47a |
95 | _assert_valid_identifier $name; |
96 | |
ae6e00b5 |
97 | unless (ref $proto_type) { |
98 | # use '||' instead of 'or' to preserve $proto_type in the error message |
99 | $proto_type = $type_map{$proto_type} |
100 | || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
2d5cf47a |
101 | } |
b72eb6ee |
102 | |
ae6e00b5 |
103 | my %type = %$proto_type; |
104 | my %clean; |
10acc8b1 |
105 | |
ae6e00b5 |
106 | $clean{name} = delete $type{name} || 'optional'; |
107 | $clean{name} =~ /^(?:optional|required|prohibited)\z/ |
108 | or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
10acc8b1 |
109 | |
ae6e00b5 |
110 | $clean{shift} = delete $type{shift} || ''; |
10acc8b1 |
111 | _assert_valid_identifier $clean{shift}, 1 if $clean{shift}; |
112 | |
698e861c |
113 | $clean{attrs} = join ' ', map delete $type{$_} || (), qw(attributes attrs); |
10acc8b1 |
114 | _assert_valid_attributes $clean{attrs} if $clean{attrs}; |
125c067e |
115 | |
59f51b8b |
116 | $clean{default_arguments} = |
117 | exists $type{default_arguments} |
118 | ? !!delete $type{default_arguments} |
119 | : 1 |
120 | ; |
63915d26 |
121 | $clean{check_argument_count} = !!delete $type{check_argument_count}; |
d8e5d540 |
122 | $clean{invocant} = !!delete $type{invocant}; |
e158cf8f |
123 | $clean{named_parameters} = !!delete $type{named_parameters}; |
51a483f8 |
124 | $clean{types} = !!delete $type{types}; |
63915d26 |
125 | |
ae6e00b5 |
126 | %type and confess "Invalid keyword property: @{[keys %type]}"; |
127 | |
128 | $spec{$name} = \%clean; |
125c067e |
129 | } |
130 | |
db81d362 |
131 | for my $kw (keys %spec) { |
132 | my $type = $spec{$kw}; |
133 | |
63915d26 |
134 | my $flags = |
135 | $type->{name} eq 'prohibited' ? FLAG_ANON_OK : |
136 | $type->{name} eq 'required' ? FLAG_NAME_OK : |
137 | FLAG_ANON_OK | FLAG_NAME_OK |
138 | ; |
139 | $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments}; |
51a483f8 |
140 | $flags |= FLAG_CHECK_NARGS | FLAG_CHECK_TARGS if $type->{check_argument_count}; |
d8e5d540 |
141 | $flags |= FLAG_INVOCANT if $type->{invocant}; |
e158cf8f |
142 | $flags |= FLAG_NAMED_PARAMS if $type->{named_parameters}; |
51a483f8 |
143 | $flags |= FLAG_TYPES_OK if $type->{types}; |
63915d26 |
144 | $^H{HINTK_FLAGS_ . $kw} = $flags; |
ae6e00b5 |
145 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift}; |
10acc8b1 |
146 | $^H{HINTK_ATTRS_ . $kw} = $type->{attrs}; |
db81d362 |
147 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
125c067e |
148 | } |
eeb7df5f |
149 | } |
150 | |
db81d362 |
151 | sub unimport { |
eeb7df5f |
152 | my $class = shift; |
125c067e |
153 | |
db81d362 |
154 | if (!@_) { |
155 | delete $^H{+HINTK_KEYWORDS}; |
125c067e |
156 | return; |
157 | } |
158 | |
db81d362 |
159 | for my $kw (@_) { |
160 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
125c067e |
161 | } |
162 | } |
163 | |
db81d362 |
164 | |
53c979f0 |
165 | our %metadata; |
166 | |
167 | sub _register_info { |
168 | my ( |
169 | $key, |
170 | $declarator, |
171 | $invocant, |
51a483f8 |
172 | $invocant_type, |
53c979f0 |
173 | $positional_required, |
174 | $positional_optional, |
175 | $named_required, |
176 | $named_optional, |
177 | $slurpy, |
51a483f8 |
178 | $slurpy_type, |
53c979f0 |
179 | ) = @_; |
180 | |
51a483f8 |
181 | my $info = { |
182 | declarator => $declarator, |
183 | invocant => defined $invocant ? [$invocant, $invocant_type] : undef, |
184 | slurpy => defined $slurpy ? [$slurpy , $slurpy_type ] : undef, |
185 | positional_required => $positional_required, |
186 | positional_optional => $positional_optional, |
187 | named_required => $named_required, |
188 | named_optional => $named_optional, |
189 | }; |
190 | |
191 | $metadata{$key} = $info; |
192 | } |
193 | |
194 | sub _mkparam1 { |
195 | my ($pair) = @_; |
196 | my ($v, $t) = @{$pair || []} or return undef; |
197 | Function::Parameters::Param->new( |
198 | name => $v, |
199 | type => $t, |
200 | ) |
201 | } |
202 | |
203 | sub _mkparams { |
204 | my @r; |
205 | while (my ($v, $t) = splice @_, 0, 2) { |
206 | push @r, Function::Parameters::Param->new( |
207 | name => $v, |
208 | type => $t, |
209 | ); |
210 | } |
211 | \@r |
53c979f0 |
212 | } |
213 | |
214 | sub info { |
215 | my ($func) = @_; |
216 | my $key = _cv_root $func or return undef; |
51a483f8 |
217 | my $info = $metadata{$key} or return undef; |
53c979f0 |
218 | require Function::Parameters::Info; |
219 | Function::Parameters::Info->new( |
51a483f8 |
220 | keyword => $info->{declarator}, |
221 | invocant => _mkparam1($info->{invocant}), |
222 | slurpy => _mkparam1($info->{slurpy}), |
223 | (map +("_$_" => _mkparams @{$info->{$_}}), glob '{positional,named}_{required,optional}') |
53c979f0 |
224 | ) |
225 | } |
226 | |
125c067e |
227 | 'ok' |
7a63380c |
228 | |
229 | __END__ |
230 | |
f2541b7d |
231 | =encoding UTF-8 |
232 | |
7a63380c |
233 | =head1 NAME |
234 | |
235 | Function::Parameters - subroutine definitions with parameter lists |
236 | |
237 | =head1 SYNOPSIS |
238 | |
81203272 |
239 | use Function::Parameters qw(:strict); |
7a63380c |
240 | |
698e861c |
241 | # simple function |
7a63380c |
242 | fun foo($bar, $baz) { |
243 | return $bar + $baz; |
244 | } |
245 | |
698e861c |
246 | # function with prototype |
d71d548b |
247 | fun mymap($fun, @args) |
248 | :(&@) |
249 | { |
7a63380c |
250 | my @res; |
251 | for (@args) { |
252 | push @res, $fun->($_); |
253 | } |
254 | @res |
255 | } |
256 | |
257 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
125c067e |
258 | |
698e861c |
259 | # method with implicit $self |
125c067e |
260 | method set_name($name) { |
261 | $self->{name} = $name; |
262 | } |
d8e5d540 |
263 | |
264 | # method with explicit invocant |
265 | method new($class: %init) { |
266 | return bless { %init }, $class; |
267 | } |
268 | |
81203272 |
269 | # function with optional parameters |
698e861c |
270 | fun search($haystack, $needle = qr/^(?!)/, $offset = 0) { |
271 | ... |
272 | } |
d8e5d540 |
273 | |
81203272 |
274 | # method with named parameters |
275 | method resize(:$width, :$height) { |
276 | $self->{width} = $width; |
277 | $self->{height} = $height; |
698e861c |
278 | } |
8dbfd12d |
279 | |
81203272 |
280 | $obj->resize(height => 4, width => 5); |
8dbfd12d |
281 | |
81203272 |
282 | # function with named optional parameters |
283 | fun search($haystack, :$needle = qr/^(?!)/, :$offset = 0) { |
284 | ... |
285 | } |
8dbfd12d |
286 | |
81203272 |
287 | my $results = search $text, offset => 200; |
8dbfd12d |
288 | |
81203272 |
289 | =head1 DESCRIPTION |
8dbfd12d |
290 | |
81203272 |
291 | This module extends Perl with keywords that let you define functions with |
292 | parameter lists. It uses Perl's L<keyword plugin|perlapi/PL_keyword_plugin> |
293 | API, so it works reliably and doesn't require a source filter. |
294 | |
295 | =head2 Basics |
296 | |
297 | The anatomy of a function (as recognized by this module): |
298 | |
299 | =over |
8dbfd12d |
300 | |
81203272 |
301 | =item 1. |
302 | |
303 | The keyword introducing the function. |
304 | |
305 | =item 2. |
306 | |
307 | The function name (optional). |
308 | |
309 | =item 3. |
310 | |
311 | The parameter list (optional). |
312 | |
313 | =item 4. |
314 | |
315 | The prototype (optional). |
316 | |
317 | =item 5. |
318 | |
319 | The attribute list (optional). |
320 | |
321 | =item 6. |
322 | |
323 | The function body. |
324 | |
325 | =back |
326 | |
327 | Example: |
328 | |
329 | # (1) (2) (3) (4) (5) (6) |
330 | fun foo ($x, $y) :($$) :lvalue { ... } |
c9a39f6b |
331 | |
81203272 |
332 | # (1) (6) |
333 | my $f = fun { ... }; |
125c067e |
334 | |
81203272 |
335 | In the following section I'm going to describe all parts in order from simplest to most complex. |
7a63380c |
336 | |
81203272 |
337 | =head3 Body |
7a63380c |
338 | |
81203272 |
339 | This is just a normal block of statements, as with L<C<sub>|perlsub>. No surprises here. |
7a63380c |
340 | |
81203272 |
341 | =head3 Name |
7a63380c |
342 | |
81203272 |
343 | If present, it specifies the name of the function being defined. As with |
344 | L<C<sub>|perlsub>, if a name is present, the whole declaration is syntactically |
345 | a statement and its effects are performed at compile time (i.e. at runtime you |
346 | can call functions whose definitions only occur later in the file). If no name |
347 | is present, the declaration is an expression that evaluates to a reference to |
348 | the function in question. No surprises here either. |
7a63380c |
349 | |
81203272 |
350 | =head3 Attributes |
7a63380c |
351 | |
81203272 |
352 | Attributes are relatively unusual in Perl code, but if you want them, they work |
353 | exactly the same as with L<C<sub>|perlsub/Subroutine-Attributes>. |
c9a39f6b |
354 | |
81203272 |
355 | =head3 Prototype |
698e861c |
356 | |
81203272 |
357 | As with L<C<sub>|perlsub/Prototypes>, a prototype, if present, contains hints as to how |
358 | the compiler should parse calls to this function. This means prototypes have no |
359 | effect if the function call is compiled before the function declaration has |
360 | been seen by the compiler or if the function to call is only determined at |
361 | runtime (e.g. because it's called as a method or through a reference). |
698e861c |
362 | |
81203272 |
363 | With L<C<sub>|perlsub>, a prototype comes directly after the function name (if |
364 | any). C<Function::Parameters> reserves this spot for the |
365 | L<parameter list|/"Parameter list">. To specify a prototype, put it as the |
366 | first attribute (e.g. C<fun foo :(&$$)>). This is syntactically unambiguous |
367 | because normal L<attributes|/Attributes> need a name after the colon. |
7a63380c |
368 | |
81203272 |
369 | =head3 Parameter list |
125c067e |
370 | |
81203272 |
371 | The parameter list is a list of variables enclosed in parentheses, except it's |
372 | actually a bit more complicated than that. A parameter list can include the |
373 | following 6 parts, all of which are optional: |
125c067e |
374 | |
81203272 |
375 | =over |
125c067e |
376 | |
81203272 |
377 | =item 1. Invocant |
125c067e |
378 | |
81203272 |
379 | This is a scalar variable followed by a colon (C<:>) and no comma. If an |
380 | invocant is present in the parameter list, the first element of |
381 | L<C<@_>|perlvar/@ARG> is automatically L<C<shift>ed|perlfunc/shift> off and |
382 | placed in this variable. This is intended for methods: |
125c067e |
383 | |
81203272 |
384 | method new($class: %init) { |
385 | return bless { %init }, $class; |
386 | } |
387 | |
388 | method throw($self:) { |
389 | die $self; |
390 | } |
125c067e |
391 | |
81203272 |
392 | =item 2. Required positional parameters |
fcaf7811 |
393 | |
81203272 |
394 | The most common kind of parameter. This is simply a comma-separated list of |
395 | scalars, which are filled from left to right with the arguments that the caller |
396 | passed in: |
fcaf7811 |
397 | |
81203272 |
398 | fun add($x, $y) { |
399 | return $x + $y; |
400 | } |
401 | |
402 | say add(2, 3); # "5" |
403 | |
404 | =item 3. Optional positional parameters |
405 | |
406 | Parameters can be marked as optional by putting an equals sign (C<=>) and an |
407 | expression (the "default argument") after them. If no corresponding argument is |
408 | passed in by the caller, the default argument will be used to initialize the |
409 | parameter: |
410 | |
411 | fun scale($base, $factor = 2) { |
412 | return $base * $factor; |
413 | } |
414 | |
415 | say scale(3, 5); # "15" |
416 | say scale(3); # "6" |
417 | |
418 | The default argument is I<not> cached. Every time a function is called with |
419 | some optional arguments missing, the corresponding default arguments are |
420 | evaluated from left to right. This makes no difference for a value like C<2> |
421 | but it is important for expressions with side effects, such as reference |
422 | constructors (C<[]>, C<{}>) or function calls. |
423 | |
424 | Default arguments see not only the surrounding lexical scope of their function |
425 | but also any preceding parameters. This allows the creation of dynamic defaults |
426 | based on previous arguments: |
427 | |
428 | method set_name($self: $nick = $self->default_nick, $real_name = $nick) { |
429 | $self->{nick} = $nick; |
430 | $self->{real_name} = $real_name; |
431 | } |
432 | |
433 | $obj->set_name("simplicio"); # same as: $obj->set_name("simplicio", "simplicio"); |
63a24d7c |
434 | |
81203272 |
435 | Because default arguments are actually evaluated as part of the function body, |
436 | you can also do silly things like this: |
437 | |
438 | fun foo($n = return "nope") { |
439 | "you gave me $n" |
440 | } |
441 | |
442 | say foo(2 + 2); # "you gave me 4" |
443 | say foo(); # "nope" |
444 | |
445 | =item 4. Required named parameters |
446 | |
447 | By putting a colon (C<:>) in front of a parameter you can make it named |
448 | instead of positional: |
449 | |
450 | fun rectangle(:$width, :$height) { |
451 | ... |
452 | } |
453 | |
454 | rectangle(width => 2, height => 5); |
455 | rectangle(height => 5, width => 2); # same thing! |
456 | |
457 | That is, the caller must specify a key name in addition to the value, but in |
458 | exchange the order of the arguments doesn't matter anymore. As with hash |
459 | initialization, you can specify the same key multiple times and the last |
460 | occurrence wins: |
461 | |
462 | rectangle(height => 1, width => 2, height => 2, height => 5; |
463 | # same as: rectangle(width => 2, height => 5); |
464 | |
465 | You can combine positional and named parameters as long as the positional |
466 | parameters come first: |
467 | |
468 | fun named_rectangle($name, :$width, :$height) { |
469 | ... |
470 | } |
471 | |
472 | named_rectangle("Avocado", width => 0.5, height => 1.2); |
473 | |
474 | =item 5. Optional named parameters |
475 | |
476 | As with positional parameters, you can make named parameters optional by |
477 | specifying a default argument after an equals sign (C<=>): |
478 | |
479 | fun rectangle(:$width, :$height, :$color = "chartreuse") { |
480 | ... |
481 | } |
482 | |
483 | rectangle(height => 10, width => 5); |
484 | # same as: rectangle(height => 10, width => 5, color => "chartreuse"); |
125c067e |
485 | |
486 | =cut |
487 | |
488 | =pod |
81203272 |
489 | |
490 | fun get($url, :$cookie_jar = HTTP::Cookies->new(), :$referrer = $url) { |
491 | ... |
492 | } |
125c067e |
493 | |
81203272 |
494 | my $data = get "http://www.example.com/", referrer => undef; # overrides $referrer = $url |
125c067e |
495 | |
81203272 |
496 | The above example shows that passing any value (even C<undef>) will override |
497 | the default argument. |
63a24d7c |
498 | |
81203272 |
499 | =item 6. Slurpy parameter |
ce052c57 |
500 | |
81203272 |
501 | Finally you can put an array or hash in the parameter list, which will gobble |
502 | up the remaining arguments (if any): |
ce052c57 |
503 | |
81203272 |
504 | fun foo($x, $y, @rest) { ... } |
505 | |
506 | foo "a", "b"; # $x = "a", $y = "b", @rest = () |
507 | foo "a", "b", "c"; # $x = "a", $y = "b", @rest = ("c") |
508 | foo "a", "b", "c", "d"; # $x = "a", $y = "b", @rest = ("c", "d") |
ce052c57 |
509 | |
81203272 |
510 | If you combine this with named parameters, the slurpy parameter will end up |
511 | containing all unrecognized keys: |
ce052c57 |
512 | |
81203272 |
513 | fun bar(:$size, @whatev) { ... } |
514 | |
515 | bar weight => 20, size => 2, location => [0, -3]; |
516 | # $size = 2, @whatev = ('weight', 20, 'location', [0, -3]) |
ce052c57 |
517 | |
81203272 |
518 | =back |
ce052c57 |
519 | |
81203272 |
520 | Apart from the L<C<shift>|perlfunc/shift> performed by the L<invocant|/"1. |
521 | Invocant">, all of the above leave L<C<@_>|perlvar/@ARG> unchanged; and if you |
522 | don't specify a parameter list at all, L<C<@_>|perlvar/@ARG> is all you get. |
d8e5d540 |
523 | |
81203272 |
524 | =head3 Keyword |
d8e5d540 |
525 | |
81203272 |
526 | The keywords provided by C<Function::Parameters> are customizable. Since |
527 | C<Function::Parameters> is actually a L<pragma|perlpragma>, the provided |
528 | keywords have lexical scope. The following import variants can be used: |
d8e5d540 |
529 | |
81203272 |
530 | =over |
273c6544 |
531 | |
81203272 |
532 | =item C<use Function::Parameters ':strict'> |
273c6544 |
533 | |
81203272 |
534 | Provides the keywords C<fun> and C<method> (described below) and enables |
535 | argument checks so that calling a function and omitting a required argument (or |
536 | passing too many arguments) will throw an error. |
273c6544 |
537 | |
81203272 |
538 | =item C<use Function::Parameters> |
273c6544 |
539 | |
81203272 |
540 | Provides the keywords C<fun> and C<method> (described below) and enables |
541 | "lax" mode: Omitting a required argument sets it to C<undef> while excess |
542 | arguments are silently ignored. |
273c6544 |
543 | |
81203272 |
544 | =item C<< use Function::Parameters { KEYWORD1 => TYPE1, KEYWORD2 => TYPE2, ... } >> |
698e861c |
545 | |
81203272 |
546 | Provides completely custom keywords as described by their types. A "type" is |
547 | either a string (one of the predefined types C<function>, C<method>, |
548 | C<classmethod>, C<function_strict>, C<method_strict>, C<classmethod_strict>) or |
549 | a reference to a hash with the following keys: |
698e861c |
550 | |
81203272 |
551 | =over |
698e861c |
552 | |
81203272 |
553 | =item C<name> |
698e861c |
554 | |
81203272 |
555 | Valid values: C<optional> (default), C<required> (all functions defined with |
556 | this keyword must have a name), and C<prohibited> (functions defined with this |
557 | keyword must be anonymous). |
698e861c |
558 | |
81203272 |
559 | =item C<shift> |
698e861c |
560 | |
81203272 |
561 | Valid values: strings that look like scalar variables. This lets you specify a |
562 | default L<invocant|/"1. Invocant">, i.e. a function defined with this keyword |
563 | that doesn't have an explicit invocant in its parameter list will automatically |
564 | L<C<shift>|perlfunc/shift> its first argument into the variable specified here. |
698e861c |
565 | |
81203272 |
566 | =item C<invocant> |
698e861c |
567 | |
81203272 |
568 | Valid values: booleans. If you set this to a true value, the keyword will |
569 | accept L<invocants|/"1. Invocant"> in parameter lists; otherwise specifying |
570 | an invocant in a function defined with this keyword is a syntax error. |
698e861c |
571 | |
81203272 |
572 | =item C<attributes> |
698e861c |
573 | |
81203272 |
574 | Valid values: strings containing (source code for) attributes. This causes any |
575 | function defined with this keyword to have the specified |
576 | L<attributes|attributes> (in addition to any attributes specified in the |
577 | function definition itself). |
698e861c |
578 | |
81203272 |
579 | =item C<default_arguments> |
698e861c |
580 | |
81203272 |
581 | Valid values: booleans. This property is on by default; use |
582 | C<< default_arguments => 0 >> to turn it off. This controls whether optional |
583 | parameters are allowed. If it is turned off, using C<=> in parameter lists is |
584 | a syntax error. |
698e861c |
585 | |
81203272 |
586 | =item C<check_argument_count> |
698e861c |
587 | |
81203272 |
588 | Valid values: booleans. If turned on, functions defined with this keyword will |
589 | automatically check that they have been passed all required arguments and no |
590 | excess arguments. If this check fails, an exception will by thrown via |
591 | L<C<Carp::croak>|Carp>. |
698e861c |
592 | |
ce052c57 |
593 | =back |
594 | |
81203272 |
595 | The predefined type C<function> is equivalent to: |
698e861c |
596 | |
597 | { |
598 | name => 'optional', |
81203272 |
599 | invocant => 0, |
698e861c |
600 | default_arguments => 1, |
601 | check_argument_count => 0, |
602 | } |
603 | |
81203272 |
604 | These are all default values, so C<function> is also equivalent to C<{}>. |
698e861c |
605 | |
81203272 |
606 | C<method> is equivalent to: |
698e861c |
607 | |
608 | { |
609 | name => 'optional', |
698e861c |
610 | shift => '$self', |
d8e5d540 |
611 | invocant => 1, |
81203272 |
612 | attributes => ':method', |
613 | default_arguments => 1, |
614 | check_argument_count => 0, |
698e861c |
615 | } |
616 | |
7817d698 |
617 | |
81203272 |
618 | C<classmethod> is equivalent to: |
698e861c |
619 | |
620 | { |
621 | name => 'optional', |
698e861c |
622 | shift => '$class', |
d8e5d540 |
623 | invocant => 1, |
81203272 |
624 | attributes => ':method', |
625 | default_arguments => 1, |
626 | check_argument_count => 0, |
698e861c |
627 | } |
ce052c57 |
628 | |
81203272 |
629 | C<function_strict>, C<method_strict>, and |
630 | C<classmethod_strict> are like C<function>, C<method>, and |
631 | C<classmethod>, respectively, but with C<< check_argument_count => 1 >>. |
63a24d7c |
632 | |
81203272 |
633 | =back |
63a24d7c |
634 | |
81203272 |
635 | Plain C<use Function::Parameters> is equivalent to |
636 | C<< use Function::Parameters { fun => 'function', method => 'method' } >>. |
63a24d7c |
637 | |
81203272 |
638 | C<use Function::Parameters qw(:strict)> is equivalent to |
639 | C<< use Function::Parameters { fun => 'function_strict', method => 'method_strict' } >>. |
63a24d7c |
640 | |
ebdc721b |
641 | =head2 Introspection |
642 | |
643 | You can ask a function at runtime what parameters it has. This functionality is |
644 | available through the function C<Function::Parameters::info> (which is not |
645 | exported, so you have to call it by its full name). It takes a reference to a |
646 | function, and returns either C<undef> (if it knows nothing about the function) |
647 | or a L<Function::Parameters::Info> object describing the parameter list. |
648 | |
649 | See L<Function::Parameters::Info> for examples. |
650 | |
81203272 |
651 | =head2 Wrapping C<Function::Parameters> |
125c067e |
652 | |
81203272 |
653 | If you want to write a wrapper around C<Function::Parameters>, you only have to |
654 | call its C<import> method. Due to its L<pragma|perlpragma> nature it always |
655 | affects the file that is currently being compiled. |
63a24d7c |
656 | |
657 | package Some::Wrapper; |
658 | use Function::Parameters (); |
659 | sub import { |
660 | Function::Parameters->import; |
698e861c |
661 | # or Function::Parameters->import(@custom_import_args); |
63a24d7c |
662 | } |
eeb7df5f |
663 | |
0175ff9a |
664 | =head2 Experimental feature: Types |
665 | |
666 | An experimental feature is now available: You can annotate parameters with |
667 | L<Moose types|Moose::Manual::Types>. That is, before each parameter you can put |
668 | a type specification consisting of identifiers (C<Foo>), unions (C<... | ...>), |
669 | and parametric types (C<...[...]>). Example: |
670 | |
671 | fun foo(Int $n, ArrayRef[String | CodeRef] $cb) { ... } |
672 | |
673 | If you do this, L<Moose> will be loaded automatically (if that hasn't happened |
674 | yet). These specifications are parsed and validated using |
675 | L<C<Moose::Util::TypeConstraints::find_or_parse_type_constraint>|Moose::Util::TypeConstraints/find_or_parse_type_constraint>. |
676 | |
677 | If you are in "lax" mode, nothing further happens and the types are ignored. If |
678 | you are in "strict" mode, C<Function::Parameters> generates code to make sure |
679 | any values passed in conform to the type (via |
d54d249f |
680 | L<< C<< $constraint->check($value) >>|Moose::Meta::TypeConstraint/$constraint->check($value) >>). |
0175ff9a |
681 | |
682 | In addition, these type constraints are inspectable through the |
683 | L<Function::Parameters::Info> object returned by |
684 | L<C<Function::Parameters::info>|/Introspection>. |
685 | |
686 | =head2 Experimental experimental feature: Type expressions |
687 | |
688 | An even more experimental feature is the ability to specify arbitrary |
689 | expressions as types. The syntax for this is like the literal types described |
690 | above, but with an expression wrapped in parentheses (C<( EXPR )>). Example: |
691 | |
692 | fun foo(('Int') $n, ($othertype) $x) { ... } |
693 | |
694 | Every type expression must return either a string (which is resolved as for |
695 | literal types), or a L<type constraint object|Moose::Meta::TypeConstraint> |
696 | (providing C<check> and C<get_message> methods). |
697 | |
698 | Note that these expressions are evaluated (once) at parse time (similar to |
699 | C<BEGIN> blocks), so make sure that any variables you use are set and any |
700 | functions you call are defined at parse time. |
701 | |
81203272 |
702 | =head2 How it works |
703 | |
704 | The module is actually written in L<C|perlxs> and uses |
705 | L<C<PL_keyword_plugin>|perlapi/PL_keyword_plugin> to generate opcodes directly. |
706 | However, you can run L<C<perl -MO=Deparse ...>|B::Deparse> on your code to see |
707 | what happens under the hood. In the simplest case (no argument checks, possibly |
708 | an L<invocant|/"1. Invocant">, required positional/slurpy parameters only), the |
709 | generated code corresponds to: |
710 | |
711 | fun foo($x, $y, @z) { ... } |
712 | # ... turns into ... |
713 | sub foo { my ($x, $y, @z) = @_; sub foo; ... } |
714 | |
715 | method bar($x, $y, @z) { ... } |
716 | # ... turns into ... |
717 | sub bar :method { my $self = shift; my ($x, $y, @z) = @_; sub bar; ... } |
718 | |
0175ff9a |
719 | =head1 SUPPORT AND DOCUMENTATION |
720 | |
721 | After installing, you can find documentation for this module with the |
722 | perldoc command. |
723 | |
724 | perldoc Function::Parameters |
725 | |
726 | You can also look for information at: |
727 | |
728 | =over |
729 | |
730 | =item MetaCPAN |
731 | |
732 | L<https://metacpan.org/module/Function%3A%3AParameters> |
733 | |
734 | =item RT, CPAN's request tracker |
735 | |
736 | L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Function-Parameters> |
737 | |
738 | =item AnnoCPAN, Annotated CPAN documentation |
739 | |
740 | L<http://annocpan.org/dist/Function-Parameters> |
741 | |
742 | =item CPAN Ratings |
743 | |
744 | L<http://cpanratings.perl.org/d/Function-Parameters> |
745 | |
746 | =item Search CPAN |
747 | |
748 | L<http://search.cpan.org/dist/Function-Parameters/> |
749 | |
750 | =back |
751 | |
ebdc721b |
752 | =head1 SEE ALSO |
753 | |
754 | L<Function::Parameters::Info> |
755 | |
7a63380c |
756 | =head1 AUTHOR |
757 | |
758 | Lukas Mai, C<< <l.mai at web.de> >> |
759 | |
760 | =head1 COPYRIGHT & LICENSE |
761 | |
db81d362 |
762 | Copyright 2010, 2011, 2012 Lukas Mai. |
7a63380c |
763 | |
764 | This program is free software; you can redistribute it and/or modify it |
765 | under the terms of either: the GNU General Public License as published |
766 | by the Free Software Foundation; or the Artistic License. |
767 | |
768 | See http://dev.perl.org/licenses/ for more information. |
769 | |
770 | =cut |