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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{"$name" doesn't look like a valid identifier}; |
21 | } |
22 | |
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23 | sub _assert_valid_attributes { |
24 | my ($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 | attrs => ':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 ${\join ', ', sort keys %type_map})]; |
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79 | } |
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80 | |
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81 | my %type = %$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 | |
91 | $clean{attrs} = delete $type{attrs} || ''; |
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 | |
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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 | |
151 | fun foo($bar, $baz) { |
152 | return $bar + $baz; |
153 | } |
154 | |
155 | fun mymap($fun, @args) :(&@) { |
156 | my @res; |
157 | for (@args) { |
158 | push @res, $fun->($_); |
159 | } |
160 | @res |
161 | } |
162 | |
163 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
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164 | |
165 | method set_name($name) { |
166 | $self->{name} = $name; |
167 | } |
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168 | |
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169 | =cut |
170 | |
171 | =pod |
172 | |
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173 | use Function::Parameters { |
174 | proc => 'function', |
175 | meth => 'method', |
176 | }; |
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177 | |
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178 | my $f = proc ($x) { $x * 2 }; |
179 | meth get_age() { |
180 | return $self->{age}; |
181 | } |
182 | |
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183 | =head1 DESCRIPTION |
184 | |
185 | This module lets you use parameter lists in your subroutines. Thanks to |
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186 | L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters. |
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187 | |
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188 | WARNING: This is my first attempt at writing L<XS code|perlxs> and I have |
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189 | almost no experience with perl's internals. So while this module might |
190 | appear to work, it could also conceivably make your programs segfault. |
191 | Consider this module alpha quality. |
192 | |
193 | =head2 Basic stuff |
194 | |
195 | To use this new functionality, you have to use C<fun> instead of C<sub> - |
196 | C<sub> continues to work as before. The syntax is almost the same as for |
197 | C<sub>, but after the subroutine name (or directly after C<fun> if you're |
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198 | writing an anonymous sub) you can write a parameter list in parentheses. This |
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199 | list consists of comma-separated variables. |
200 | |
201 | The effect of C<fun foo($bar, $baz) {> is as if you'd written |
202 | C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply |
203 | copied into C<my> and initialized from L<@_|perlvar/"@_">. |
204 | |
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205 | In addition you can use C<method>, which understands the same syntax as C<fun> |
206 | but automatically creates a C<$self> variable for you. So by writing |
207 | C<method foo($bar, $baz) {> you get the same effect as |
208 | C<sub foo { my $self = shift; my ($bar, $baz) = @_; >. |
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209 | |
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210 | =head2 Customizing the generated keywords |
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211 | |
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212 | You can customize the names of the keywords injected into your scope. To do |
213 | that you pass a hash reference in the import list: |
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214 | |
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215 | use Function::Parameters { proc => 'function', meth => 'method' }; # -or- |
216 | use Function::Parameters { proc => 'function' }; # -or- |
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217 | use Function::Parameters { meth => 'method' }; # etc. |
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218 | |
219 | The first line creates two keywords, C<proc> and C<meth> (for defining |
220 | functions and methods, respectively). The last two lines only create one |
221 | keyword. Generally the hash keys can be any identifiers you want while the |
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222 | values have to be either C<function>, C<method>, C<classmethod> or a hash |
223 | reference (see below). The difference between C<function> and C<method> is that |
224 | C<method>s automatically L<shift|perlfunc/shift> their first argument into |
225 | C<$self> (C<classmethod>s are similar but shift into C<$class>). |
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226 | |
227 | The following shortcuts are available: |
228 | |
229 | use Function::Parameters; |
230 | # is equivalent to # |
231 | use Function::Parameters { fun => 'function', method => 'method' }; |
232 | |
233 | =cut |
234 | |
235 | =pod |
236 | |
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237 | The following shortcuts are deprecated and may be removed from a future version |
238 | of the module: |
239 | |
240 | # DEPRECATED |
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241 | use Function::Parameters 'foo'; |
242 | # is equivalent to # |
243 | use Function::Parameters { 'foo' => 'function' }; |
244 | |
245 | =cut |
246 | |
247 | =pod |
248 | |
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249 | # DEPRECATED |
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250 | use Function::Parameters 'foo', 'bar'; |
251 | # is equivalent to # |
252 | use Function::Parameters { 'foo' => 'function', 'bar' => 'method' }; |
253 | |
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254 | That is, if you want to pass arguments to L<Function::Parameters>, use a |
255 | hashref, not a list of strings. |
256 | |
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257 | You can customize things even more by passing a hashref instead of C<function> |
258 | or C<method>. This hash can have the following keys: |
259 | |
260 | =over |
261 | |
262 | =item C<name> |
263 | |
264 | Valid values: C<optional> (default), C<required> (all uses of this keyword must |
265 | specify a function name), and C<prohibited> (all uses of this keyword must not |
266 | specify a function name). This means a C<< name => 'prohibited' >> keyword can |
267 | only be used for defining anonymous functions. |
268 | |
269 | =item C<shift> |
270 | |
271 | Valid values: strings that look like a scalar variable. Any function created by |
272 | this keyword will automatically L<shift|perlfunc/shift> its first argument into |
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273 | a local variable whose name is specified here. |
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274 | |
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275 | =item C<attrs> |
276 | |
277 | Valid values: strings that are valid source code for attributes. Any value |
278 | specified here will be inserted as a subroutine attribute in the generated |
279 | code. Thus: |
280 | |
281 | use Function::Parameters { sub_l => { attrs => ':lvalue' } }; |
282 | sub_l foo() { |
283 | ... |
284 | } |
285 | |
286 | turns into |
287 | |
288 | sub foo :lvalue { |
289 | ... |
290 | } |
291 | |
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292 | =back |
293 | |
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294 | Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, plain |
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295 | C<'method'> is equivalent to |
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296 | C<< { name => 'optional', shift => '$self', attrs => ':method' } >>, and plain |
297 | C<'classmethod'> is equivalent to |
298 | C<< { name => 'optional', shift => '$class', attrs => ':method' } >>. |
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299 | |
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300 | =head2 Syntax and generated code |
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301 | |
302 | Normally, Perl subroutines are not in scope in their own body, meaning the |
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303 | parser doesn't know the name C<foo> or its prototype while processing the body |
304 | of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as |
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305 | C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the |
306 | interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger |
307 | a I<foo() called too early to check prototype> warning. This module attempts |
308 | to fix all of this by adding a subroutine declaration before the definition, |
309 | so the parser knows the name (and possibly prototype) while it processes the |
310 | body. Thus C<fun foo($x) :($) { $x }> really turns into |
311 | C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>. |
312 | |
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313 | If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can |
314 | put them after the parameter list with their usual syntax. |
315 | |
316 | Syntactically, these new parameter lists live in the spot normally occupied |
317 | by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by |
318 | specifying it as the first attribute (this is syntactically unambiguous |
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319 | because normal attributes have to start with a letter while a prototype starts |
320 | with C<(>). |
321 | |
322 | As an example, the following declaration uses every feature available |
323 | (subroutine name, parameter list, prototype, attributes, and implicit |
324 | C<$self>): |
325 | |
326 | method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) { |
327 | ... |
328 | } |
329 | |
330 | And here's what it turns into: |
331 | |
332 | sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_; |
333 | ... |
334 | } |
335 | |
336 | Another example: |
337 | |
338 | my $coderef = fun ($p, $q) :(;$$) |
339 | :lvalue |
340 | :Gazebo((>:O)) { |
341 | ... |
342 | }; |
343 | |
344 | And the generated code: |
345 | |
346 | my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_; |
347 | ... |
348 | }; |
349 | |
350 | =head2 Wrapping Function::Parameters |
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351 | |
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352 | If you want to wrap L<Function::Parameters>, you just have to call its |
353 | C<import> method. It always applies to the file that is currently being parsed |
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354 | and its effects are lexical (i.e. it works like L<warnings> or L<strict>): |
355 | |
356 | package Some::Wrapper; |
357 | use Function::Parameters (); |
358 | sub import { |
359 | Function::Parameters->import; |
360 | # or Function::Parameters->import(@other_import_args); |
361 | } |
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362 | |
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363 | =head1 AUTHOR |
364 | |
365 | Lukas Mai, C<< <l.mai at web.de> >> |
366 | |
367 | =head1 COPYRIGHT & LICENSE |
368 | |
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369 | Copyright 2010, 2011, 2012 Lukas Mai. |
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370 | |
371 | This program is free software; you can redistribute it and/or modify it |
372 | under the terms of either: the GNU General Public License as published |
373 | by the Free Software Foundation; or the Artistic License. |
374 | |
375 | See http://dev.perl.org/licenses/ for more information. |
376 | |
377 | =cut |