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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 XSLoader; |
9 | BEGIN { |
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10 | our $VERSION = '0.05_02'; |
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11 | XSLoader::load; |
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12 | } |
13 | |
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14 | use Carp qw(confess); |
15 | use bytes (); |
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16 | |
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17 | sub _assert_valid_identifier { |
18 | my ($name, $with_dollar) = @_; |
19 | my $bonus = $with_dollar ? '\$' : ''; |
20 | $name =~ /^${bonus}[^\W\d]\w*\z/ |
21 | or confess qq{"$name" doesn't look like a valid identifier}; |
22 | } |
23 | |
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24 | my @bare_arms = qw(function method); |
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25 | my %type_map = ( |
26 | function => { name => 'optional' }, |
27 | method => { name => 'optional', shift => '$self' }, |
28 | ); |
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29 | |
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30 | sub import { |
31 | my $class = shift; |
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32 | |
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33 | @_ or @_ = ('fun', 'method'); |
34 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
35 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]} |
36 | or return; |
37 | } |
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38 | |
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39 | my %spec; |
40 | |
41 | my $bare = 0; |
42 | for my $proto (@_) { |
43 | my $item = ref $proto |
44 | ? $proto |
45 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
46 | ; |
47 | my ($name, $type) = @$item; |
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48 | _assert_valid_identifier $name; |
49 | |
50 | unless (ref $type) { |
51 | # use '||' instead of 'or' to preserve $type in the error message |
52 | $type = $type_map{$type} |
53 | || confess qq["$type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
54 | } |
55 | $type->{name} ||= 'optional'; |
56 | $type->{name} =~ /^(?:optional|required|prohibited)\z/ |
57 | or confess qq["$type->{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
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58 | if ($type->{shift}) { |
59 | _assert_valid_identifier $type->{shift}, 1; |
60 | bytes::length($type->{shift}) < SHIFT_NAME_LIMIT |
61 | or confess qq["$type->{shift}" is longer than I can handle]; |
62 | } |
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63 | |
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64 | $spec{$name} = $type; |
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65 | } |
66 | |
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67 | for my $kw (keys %spec) { |
68 | my $type = $spec{$kw}; |
69 | |
70 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift} || ''; |
71 | $^H{HINTK_NAME_ . $kw} = |
72 | $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED : |
73 | $type->{name} eq 'required' ? FLAG_NAME_REQUIRED : |
74 | FLAG_NAME_OPTIONAL |
75 | ; |
76 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
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77 | } |
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78 | } |
79 | |
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80 | sub unimport { |
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81 | my $class = shift; |
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82 | |
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83 | if (!@_) { |
84 | delete $^H{+HINTK_KEYWORDS}; |
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85 | return; |
86 | } |
87 | |
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88 | for my $kw (@_) { |
89 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
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90 | } |
91 | } |
92 | |
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93 | |
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94 | 'ok' |
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95 | |
96 | __END__ |
97 | |
98 | =head1 NAME |
99 | |
100 | Function::Parameters - subroutine definitions with parameter lists |
101 | |
102 | =head1 SYNOPSIS |
103 | |
104 | use Function::Parameters; |
105 | |
106 | fun foo($bar, $baz) { |
107 | return $bar + $baz; |
108 | } |
109 | |
110 | fun mymap($fun, @args) :(&@) { |
111 | my @res; |
112 | for (@args) { |
113 | push @res, $fun->($_); |
114 | } |
115 | @res |
116 | } |
117 | |
118 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
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119 | |
120 | method set_name($name) { |
121 | $self->{name} = $name; |
122 | } |
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123 | |
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124 | =cut |
125 | |
126 | =pod |
127 | |
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128 | use Function::Parameters { |
129 | proc => 'function', |
130 | meth => 'method', |
131 | }; |
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132 | |
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133 | my $f = proc ($x) { $x * 2 }; |
134 | meth get_age() { |
135 | return $self->{age}; |
136 | } |
137 | |
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138 | =head1 DESCRIPTION |
139 | |
140 | This module lets you use parameter lists in your subroutines. Thanks to |
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141 | L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters. |
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142 | |
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143 | WARNING: This is my first attempt at writing L<XS code|perlxs> and I have |
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144 | almost no experience with perl's internals. So while this module might |
145 | appear to work, it could also conceivably make your programs segfault. |
146 | Consider this module alpha quality. |
147 | |
148 | =head2 Basic stuff |
149 | |
150 | To use this new functionality, you have to use C<fun> instead of C<sub> - |
151 | C<sub> continues to work as before. The syntax is almost the same as for |
152 | C<sub>, but after the subroutine name (or directly after C<fun> if you're |
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153 | writing an anonymous sub) you can write a parameter list in parentheses. This |
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154 | list consists of comma-separated variables. |
155 | |
156 | The effect of C<fun foo($bar, $baz) {> is as if you'd written |
157 | C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply |
158 | copied into C<my> and initialized from L<@_|perlvar/"@_">. |
159 | |
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160 | In addition you can use C<method>, which understands the same syntax as C<fun> |
161 | but automatically creates a C<$self> variable for you. So by writing |
162 | C<method foo($bar, $baz) {> you get the same effect as |
163 | C<sub foo { my $self = shift; my ($bar, $baz) = @_; >. |
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164 | |
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165 | =head2 Customizing the generated keywords |
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166 | |
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167 | You can customize the names of the keywords injected into your scope. To do |
168 | that you pass a hash reference in the import list: |
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169 | |
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170 | use Function::Parameters { proc => 'function', meth => 'method' }; # -or- |
171 | use Function::Parameters { proc => 'function' }; # -or- |
172 | use Function::Parameters { meth => 'method' }; |
173 | |
174 | The first line creates two keywords, C<proc> and C<meth> (for defining |
175 | functions and methods, respectively). The last two lines only create one |
176 | keyword. Generally the hash keys can be any identifiers you want while the |
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177 | values have to be either C<function>, C<method>, or a hash reference (see |
178 | below). The difference between C<function> and C<method> is that C<method>s |
179 | automatically L<shift|perlfunc/shift> their first argument into C<$self>. |
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180 | |
181 | The following shortcuts are available: |
182 | |
183 | use Function::Parameters; |
184 | # is equivalent to # |
185 | use Function::Parameters { fun => 'function', method => 'method' }; |
186 | |
187 | =cut |
188 | |
189 | =pod |
190 | |
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191 | The following shortcuts are deprecated and may be removed from a future version |
192 | of the module: |
193 | |
194 | # DEPRECATED |
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195 | use Function::Parameters 'foo'; |
196 | # is equivalent to # |
197 | use Function::Parameters { 'foo' => 'function' }; |
198 | |
199 | =cut |
200 | |
201 | =pod |
202 | |
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203 | # DEPRECATED |
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204 | use Function::Parameters 'foo', 'bar'; |
205 | # is equivalent to # |
206 | use Function::Parameters { 'foo' => 'function', 'bar' => 'method' }; |
207 | |
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208 | That is, if you want to pass arguments to L<Function::Parameters>, use a |
209 | hashref, not a list of strings. |
210 | |
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211 | You can customize things even more by passing a hashref instead of C<function> |
212 | or C<method>. This hash can have the following keys: |
213 | |
214 | =over |
215 | |
216 | =item C<name> |
217 | |
218 | Valid values: C<optional> (default), C<required> (all uses of this keyword must |
219 | specify a function name), and C<prohibited> (all uses of this keyword must not |
220 | specify a function name). This means a C<< name => 'prohibited' >> keyword can |
221 | only be used for defining anonymous functions. |
222 | |
223 | =item C<shift> |
224 | |
225 | Valid values: strings that look like a scalar variable. Any function created by |
226 | this keyword will automatically L<shift|perlfunc/shift> its first argument into |
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227 | a local variable whose name is specified here. |
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228 | |
229 | =back |
230 | |
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231 | Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, and plain |
232 | C<'method'> is equivalent to C<< { name => 'optional', shift => '$self' } >>. |
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233 | |
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234 | =head2 Syntax and generated code |
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235 | |
236 | Normally, Perl subroutines are not in scope in their own body, meaning the |
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237 | parser doesn't know the name C<foo> or its prototype while processing the body |
238 | of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as |
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239 | C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the |
240 | interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger |
241 | a I<foo() called too early to check prototype> warning. This module attempts |
242 | to fix all of this by adding a subroutine declaration before the definition, |
243 | so the parser knows the name (and possibly prototype) while it processes the |
244 | body. Thus C<fun foo($x) :($) { $x }> really turns into |
245 | C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>. |
246 | |
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247 | If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can |
248 | put them after the parameter list with their usual syntax. |
249 | |
250 | Syntactically, these new parameter lists live in the spot normally occupied |
251 | by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by |
252 | specifying it as the first attribute (this is syntactically unambiguous |
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253 | because normal attributes have to start with a letter while a prototype starts |
254 | with C<(>). |
255 | |
256 | As an example, the following declaration uses every feature available |
257 | (subroutine name, parameter list, prototype, attributes, and implicit |
258 | C<$self>): |
259 | |
260 | method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) { |
261 | ... |
262 | } |
263 | |
264 | And here's what it turns into: |
265 | |
266 | sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_; |
267 | ... |
268 | } |
269 | |
270 | Another example: |
271 | |
272 | my $coderef = fun ($p, $q) :(;$$) |
273 | :lvalue |
274 | :Gazebo((>:O)) { |
275 | ... |
276 | }; |
277 | |
278 | And the generated code: |
279 | |
280 | my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_; |
281 | ... |
282 | }; |
283 | |
284 | =head2 Wrapping Function::Parameters |
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285 | |
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286 | If you want to wrap L<Function::Parameters>, you just have to call its |
287 | C<import> method. It always applies to the file that is currently being parsed |
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288 | and its effects are lexical (i.e. it works like L<warnings> or L<strict>): |
289 | |
290 | package Some::Wrapper; |
291 | use Function::Parameters (); |
292 | sub import { |
293 | Function::Parameters->import; |
294 | # or Function::Parameters->import(@other_import_args); |
295 | } |
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296 | |
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297 | =head1 AUTHOR |
298 | |
299 | Lukas Mai, C<< <l.mai at web.de> >> |
300 | |
301 | =head1 COPYRIGHT & LICENSE |
302 | |
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303 | Copyright 2010, 2011, 2012 Lukas Mai. |
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304 | |
305 | This program is free software; you can redistribute it and/or modify it |
306 | under the terms of either: the GNU General Public License as published |
307 | by the Free Software Foundation; or the Artistic License. |
308 | |
309 | See http://dev.perl.org/licenses/ for more information. |
310 | |
311 | =cut |