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1 | package Function::Parameters; |
2 | |
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3 | use v5.14.0; |
4 | |
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5 | use strict; |
6 | use warnings; |
7 | |
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8 | use Carp qw(confess); |
9 | |
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10 | use XSLoader; |
11 | BEGIN { |
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12 | our $VERSION = '0.06'; |
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13 | XSLoader::load; |
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14 | } |
15 | |
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16 | sub _assert_valid_identifier { |
17 | my ($name, $with_dollar) = @_; |
18 | my $bonus = $with_dollar ? '\$' : ''; |
19 | $name =~ /^${bonus}[^\W\d]\w*\z/ |
20 | or confess qq{"$name" doesn't look like a valid identifier}; |
21 | } |
22 | |
b72eb6ee |
23 | sub _assert_valid_attributes { |
24 | my ($attrs) = @_; |
25 | $attrs =~ /^\s*:\s*[^\W\d]\w*\s*(?:(?:\s|:\s*)[^\W\d]\w*\s*)*(?:\(|\z)/ |
26 | or confess qq{"$attrs" doesn't look like valid attributes}; |
27 | } |
28 | |
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29 | my @bare_arms = qw(function method); |
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30 | my %type_map = ( |
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31 | function => { |
32 | name => 'optional', |
33 | default_arguments => 1, |
34 | check_argument_count => 0, |
35 | }, |
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36 | method => { |
37 | name => 'optional', |
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38 | default_arguments => 1, |
39 | check_argument_count => 0, |
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40 | attrs => ':method', |
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41 | shift => '$self', |
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42 | }, |
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43 | classmethod => { |
44 | name => 'optional', |
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45 | default_arguments => 1, |
46 | check_argument_count => 0, |
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47 | attributes => ':method', |
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48 | shift => '$class', |
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49 | }, |
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50 | ); |
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51 | |
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52 | sub import { |
53 | my $class = shift; |
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54 | |
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55 | @_ or @_ = { |
56 | fun => 'function', |
57 | method => 'method', |
58 | }; |
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59 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
60 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]} |
61 | or return; |
62 | } |
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63 | |
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64 | my %spec; |
65 | |
66 | my $bare = 0; |
67 | for my $proto (@_) { |
68 | my $item = ref $proto |
69 | ? $proto |
70 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
71 | ; |
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72 | my ($name, $proto_type) = @$item; |
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73 | _assert_valid_identifier $name; |
74 | |
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75 | unless (ref $proto_type) { |
76 | # use '||' instead of 'or' to preserve $proto_type in the error message |
77 | $proto_type = $type_map{$proto_type} |
78 | || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
2d5cf47a |
79 | } |
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80 | |
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81 | my %type = %$proto_type; |
82 | my %clean; |
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83 | |
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84 | $clean{name} = delete $type{name} || 'optional'; |
85 | $clean{name} =~ /^(?:optional|required|prohibited)\z/ |
86 | or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
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87 | |
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88 | $clean{shift} = delete $type{shift} || ''; |
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89 | _assert_valid_identifier $clean{shift}, 1 if $clean{shift}; |
90 | |
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91 | $clean{attrs} = join ' ', map delete $type{$_} || (), qw(attributes attrs); |
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92 | _assert_valid_attributes $clean{attrs} if $clean{attrs}; |
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93 | |
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94 | $clean{default_arguments} = |
95 | exists $type{default_arguments} |
96 | ? !!delete $type{default_arguments} |
97 | : 1 |
98 | ; |
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99 | $clean{check_argument_count} = !!delete $type{check_argument_count}; |
100 | |
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101 | %type and confess "Invalid keyword property: @{[keys %type]}"; |
102 | |
103 | $spec{$name} = \%clean; |
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104 | } |
105 | |
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106 | for my $kw (keys %spec) { |
107 | my $type = $spec{$kw}; |
108 | |
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109 | my $flags = |
110 | $type->{name} eq 'prohibited' ? FLAG_ANON_OK : |
111 | $type->{name} eq 'required' ? FLAG_NAME_OK : |
112 | FLAG_ANON_OK | FLAG_NAME_OK |
113 | ; |
114 | $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments}; |
115 | $flags |= FLAG_CHECK_NARGS if $type->{check_argument_count}; |
116 | $^H{HINTK_FLAGS_ . $kw} = $flags; |
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117 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift}; |
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118 | $^H{HINTK_ATTRS_ . $kw} = $type->{attrs}; |
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119 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
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120 | } |
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121 | } |
122 | |
db81d362 |
123 | sub unimport { |
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124 | my $class = shift; |
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125 | |
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126 | if (!@_) { |
127 | delete $^H{+HINTK_KEYWORDS}; |
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128 | return; |
129 | } |
130 | |
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131 | for my $kw (@_) { |
132 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
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133 | } |
134 | } |
135 | |
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136 | |
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137 | 'ok' |
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138 | |
139 | __END__ |
140 | |
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141 | =encoding UTF-8 |
142 | |
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143 | =head1 NAME |
144 | |
145 | Function::Parameters - subroutine definitions with parameter lists |
146 | |
147 | =head1 SYNOPSIS |
148 | |
149 | use Function::Parameters; |
150 | |
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151 | # simple function |
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152 | fun foo($bar, $baz) { |
153 | return $bar + $baz; |
154 | } |
155 | |
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156 | # function with prototype |
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157 | fun mymap($fun, @args) :(&@) { |
158 | my @res; |
159 | for (@args) { |
160 | push @res, $fun->($_); |
161 | } |
162 | @res |
163 | } |
164 | |
165 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
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166 | |
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167 | # method with implicit $self |
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168 | method set_name($name) { |
169 | $self->{name} = $name; |
170 | } |
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171 | |
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172 | # function with default arguments |
173 | fun search($haystack, $needle = qr/^(?!)/, $offset = 0) { |
174 | ... |
175 | } |
176 | |
177 | # method with default arguments |
178 | method skip($amount = 1) { |
179 | $self->{position} += $amount; |
180 | } |
181 | |
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182 | =cut |
183 | |
184 | =pod |
185 | |
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186 | # use different keywords |
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187 | use Function::Parameters { |
188 | proc => 'function', |
189 | meth => 'method', |
190 | }; |
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191 | |
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192 | my $f = proc ($x) { $x * 2 }; |
193 | meth get_age() { |
194 | return $self->{age}; |
195 | } |
196 | |
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197 | =head1 DESCRIPTION |
198 | |
199 | This module lets you use parameter lists in your subroutines. Thanks to |
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200 | L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters. |
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201 | |
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202 | WARNING: This is my first attempt at writing L<XS code|perlxs> and I have |
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203 | almost no experience with perl's internals. So while this module might |
204 | appear to work, it could also conceivably make your programs segfault. |
205 | Consider this module alpha quality. |
206 | |
207 | =head2 Basic stuff |
208 | |
209 | To use this new functionality, you have to use C<fun> instead of C<sub> - |
210 | C<sub> continues to work as before. The syntax is almost the same as for |
211 | C<sub>, but after the subroutine name (or directly after C<fun> if you're |
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212 | writing an anonymous sub) you can write a parameter list in parentheses. This |
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213 | list consists of comma-separated variables. |
214 | |
215 | The effect of C<fun foo($bar, $baz) {> is as if you'd written |
216 | C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply |
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217 | copied into L<my|perlfunc/my-EXPR> and initialized from L<@_|perlvar/"@_">. |
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218 | |
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219 | In addition you can use C<method>, which understands the same syntax as C<fun> |
220 | but automatically creates a C<$self> variable for you. So by writing |
221 | C<method foo($bar, $baz) {> you get the same effect as |
222 | C<sub foo { my $self = shift; my ($bar, $baz) = @_; >. |
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223 | |
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224 | =head2 Customizing the generated keywords |
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225 | |
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226 | You can customize the names of the keywords injected into your scope. To do |
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227 | that you pass a reference to a hash mapping keywords to types in the import |
228 | list: |
229 | |
230 | use Function::Parameters { |
231 | KEYWORD1 => TYPE1, |
232 | KEYWORD2 => TYPE2, |
233 | ... |
234 | }; |
235 | |
236 | Or more concretely: |
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237 | |
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238 | use Function::Parameters { proc => 'function', meth => 'method' }; # -or- |
239 | use Function::Parameters { proc => 'function' }; # -or- |
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240 | use Function::Parameters { meth => 'method' }; # etc. |
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241 | |
242 | The first line creates two keywords, C<proc> and C<meth> (for defining |
243 | functions and methods, respectively). The last two lines only create one |
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244 | keyword. Generally the hash keys (keywords) can be any identifiers you want |
245 | while the values (types) have to be either C<'function'>, C<'method'>, |
246 | C<'classmethod'>, or a hash reference (see below). The main difference between |
247 | C<'function'> and C<'method'> is that C<'method'>s automatically |
248 | L<shift|perlfunc/shift> their first argument into C<$self> (C<'classmethod'>s |
249 | are similar but shift into C<$class>). |
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250 | |
251 | The following shortcuts are available: |
252 | |
253 | use Function::Parameters; |
254 | # is equivalent to # |
255 | use Function::Parameters { fun => 'function', method => 'method' }; |
256 | |
257 | =cut |
258 | |
259 | =pod |
260 | |
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261 | The following shortcuts are deprecated and may be removed from a future version |
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262 | of this module: |
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263 | |
264 | # DEPRECATED |
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265 | use Function::Parameters 'foo'; |
266 | # is equivalent to # |
267 | use Function::Parameters { 'foo' => 'function' }; |
268 | |
269 | =cut |
270 | |
271 | =pod |
272 | |
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273 | # DEPRECATED |
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274 | use Function::Parameters 'foo', 'bar'; |
275 | # is equivalent to # |
276 | use Function::Parameters { 'foo' => 'function', 'bar' => 'method' }; |
277 | |
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278 | That is, if you want to pass arguments to L<Function::Parameters>, use a |
279 | hashref, not a list of strings. |
280 | |
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281 | You can customize the properties of the generated keywords even more by passing |
282 | a hashref instead of a string. This hash can have the following keys: |
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283 | |
284 | =over |
285 | |
286 | =item C<name> |
287 | |
288 | Valid values: C<optional> (default), C<required> (all uses of this keyword must |
289 | specify a function name), and C<prohibited> (all uses of this keyword must not |
290 | specify a function name). This means a C<< name => 'prohibited' >> keyword can |
291 | only be used for defining anonymous functions. |
292 | |
293 | =item C<shift> |
294 | |
295 | Valid values: strings that look like a scalar variable. Any function created by |
296 | this keyword will automatically L<shift|perlfunc/shift> its first argument into |
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297 | a local variable whose name is specified here. |
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298 | |
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299 | =item C<attributes>, C<attrs> |
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300 | |
301 | Valid values: strings that are valid source code for attributes. Any value |
302 | specified here will be inserted as a subroutine attribute in the generated |
303 | code. Thus: |
304 | |
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305 | use Function::Parameters { sub_l => { attributes => ':lvalue' } }; |
273c6544 |
306 | sub_l foo() { |
307 | ... |
308 | } |
309 | |
310 | turns into |
311 | |
312 | sub foo :lvalue { |
313 | ... |
314 | } |
315 | |
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316 | It is recommended that you use C<attributes> in new code but C<attrs> is also |
317 | accepted for now. |
318 | |
319 | =item C<default_arguments> |
320 | |
321 | Valid values: booleans. This property is on by default, so you have to pass |
322 | C<< default_arguments => 0 >> to turn it off. If it is disabled, using C<=> in |
323 | a parameter list causes a syntax error. Otherwise it lets you specify |
324 | default arguments directly in the parameter list: |
325 | |
326 | fun foo($x, $y = 42, $z = []) { |
327 | ... |
328 | } |
329 | |
330 | turns into |
331 | |
332 | sub foo { |
333 | my ($x, $y, $z) = @_; |
334 | $y = 42 if @_ < 2; |
335 | $z = [] if @_ < 3; |
336 | ... |
337 | } |
338 | |
339 | except that none of the parameters are in scope in the expressions that specify |
340 | default values. Thus: |
341 | |
342 | my $var = "outer"; |
343 | |
344 | fun foo($var, $wat = $var) { |
345 | # $wat will default to "outer", not to what was passed |
346 | # as the first argument! |
347 | ... |
348 | } |
349 | |
350 | This may change in a future version of this module. |
351 | |
352 | =item C<check_argument_count> |
353 | |
354 | Valid values: booleans. This property is off by default. If it is enabled, the |
355 | generated code will include checks to make sure the number of passed arguments |
356 | is correct (and otherwise throw an exception via L<Carp::croak|Carp>): |
357 | |
358 | fun foo($x, $y = 42, $z = []) { |
359 | ... |
360 | } |
361 | |
362 | turns into |
363 | |
364 | sub foo { |
365 | Carp::croak "Not enough arguments for fun foo" if @_ < 1; |
366 | Carp::croak "Too many arguments for fun foo" if @_ > 3; |
367 | my ($x, $y, $z) = @_; |
368 | $y = 42 if @_ < 2; |
369 | $z = [] if @_ < 3; |
370 | ... |
371 | } |
372 | |
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373 | =back |
374 | |
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375 | Plain C<'function'> is equivalent to: |
376 | |
377 | { |
378 | name => 'optional', |
379 | default_arguments => 1, |
380 | check_argument_count => 0, |
381 | } |
382 | |
383 | (These are all default values so C<'function'> is also equivalent to C<{}>.) |
384 | |
385 | C<'method'> is equivalent to: |
386 | |
387 | { |
388 | name => 'optional', |
389 | default_arguments => 1, |
390 | check_argument_count => 0, |
391 | attributes => ':method', |
392 | shift => '$self', |
393 | } |
394 | |
395 | C<'classmethod'> is equivalent to: |
396 | |
397 | { |
398 | name => 'optional', |
399 | default_arguments => 1, |
400 | check_argument_count => 0, |
401 | attributes => ':method', |
402 | shift => '$class', |
403 | } |
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404 | |
63a24d7c |
405 | =head2 Syntax and generated code |
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406 | |
407 | Normally, Perl subroutines are not in scope in their own body, meaning the |
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408 | parser doesn't know the name C<foo> or its prototype while processing the body |
409 | of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as |
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410 | C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the |
411 | interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger |
412 | a I<foo() called too early to check prototype> warning. This module attempts |
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413 | to fix all of this by adding a subroutine declaration before the function body, |
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414 | so the parser knows the name (and possibly prototype) while it processes the |
415 | body. Thus C<fun foo($x) :($) { $x }> really turns into |
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416 | C<sub foo ($) { sub foo ($); my ($x) = @_; $x }>. |
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417 | |
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418 | If you need L<subroutine attributes|perlsub/Subroutine-Attributes>, you can |
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419 | put them after the parameter list with their usual syntax. |
420 | |
421 | Syntactically, these new parameter lists live in the spot normally occupied |
422 | by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by |
423 | specifying it as the first attribute (this is syntactically unambiguous |
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424 | because normal attributes have to start with a letter while a prototype starts |
425 | with C<(>). |
426 | |
698e861c |
427 | As an example, the following declaration uses every available feature |
428 | (subroutine name, parameter list, default arguments, prototype, default |
429 | attributes, attributes, argument count checks, and implicit C<$self>): |
63a24d7c |
430 | |
698e861c |
431 | method foo($x, $y, $z = sqrt 5) :($$$;$) :lvalue :Banana(2 + 2) { |
63a24d7c |
432 | ... |
433 | } |
434 | |
435 | And here's what it turns into: |
436 | |
698e861c |
437 | sub foo ($$$;$) :method :lvalue :Banana(2 + 2) { |
438 | sub foo ($$$;$); |
439 | Carp::croak "Not enough arguments for method foo" if @_ < 2; |
440 | Carp::croak "Too many arguments for method foo" if @_ > 4; |
441 | my $self = shift; |
442 | my ($x, $y, $z) = @_; |
443 | $z = sqrt 5 if @_ < 3; |
63a24d7c |
444 | ... |
445 | } |
446 | |
447 | Another example: |
448 | |
449 | my $coderef = fun ($p, $q) :(;$$) |
450 | :lvalue |
451 | :Gazebo((>:O)) { |
452 | ... |
453 | }; |
454 | |
455 | And the generated code: |
456 | |
698e861c |
457 | my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { |
458 | # vvv only if check_argument_count is enabled vvv |
459 | Carp::croak "Not enough arguments for fun (anon)" if @_ < 2; |
460 | Carp::croak "Too many arguments for fun (anon)" if @_ > 2; |
461 | my ($p, $q) = @_; |
63a24d7c |
462 | ... |
463 | }; |
464 | |
465 | =head2 Wrapping Function::Parameters |
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466 | |
db81d362 |
467 | If you want to wrap L<Function::Parameters>, you just have to call its |
468 | C<import> method. It always applies to the file that is currently being parsed |
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469 | and its effects are L<lexical|perlpragma> (i.e. it works like L<warnings> or |
470 | L<strict>). |
63a24d7c |
471 | |
472 | package Some::Wrapper; |
473 | use Function::Parameters (); |
474 | sub import { |
475 | Function::Parameters->import; |
698e861c |
476 | # or Function::Parameters->import(@custom_import_args); |
63a24d7c |
477 | } |
eeb7df5f |
478 | |
7a63380c |
479 | =head1 AUTHOR |
480 | |
481 | Lukas Mai, C<< <l.mai at web.de> >> |
482 | |
483 | =head1 COPYRIGHT & LICENSE |
484 | |
db81d362 |
485 | Copyright 2010, 2011, 2012 Lukas Mai. |
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486 | |
487 | This program is free software; you can redistribute it and/or modify it |
488 | under the terms of either: the GNU General Public License as published |
489 | by the Free Software Foundation; or the Artistic License. |
490 | |
491 | See http://dev.perl.org/licenses/ for more information. |
492 | |
493 | =cut |