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1 | package Function::Parameters; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | |
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6 | use XSLoader; |
7 | BEGIN { |
8 | our $VERSION = '0.05_01'; |
9 | XSLoader::load; |
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10 | } |
11 | |
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12 | use B::Hooks::EndOfScope qw(on_scope_end); |
13 | use Carp qw(confess); |
14 | use bytes (); |
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15 | |
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16 | sub _assert_valid_identifier { |
17 | my ($name, $with_dollar) = @_; |
18 | my $bonus = $with_dollar ? '\$' : ''; |
19 | $name =~ /^${bonus}[^\W\d]\w*\z/ |
20 | or confess qq{"$name" doesn't look like a valid identifier}; |
21 | } |
22 | |
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23 | my @bare_arms = qw(function method); |
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24 | my %type_map = ( |
25 | function => { name => 'optional' }, |
26 | method => { name => 'optional', shift => '$self' }, |
27 | ); |
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28 | |
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29 | sub import { |
30 | my $class = shift; |
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31 | |
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32 | @_ or @_ = ('fun', 'method'); |
33 | if (@_ == 1 && ref($_[0]) eq 'HASH') { |
34 | @_ = map [$_, $_[0]{$_}], keys %{$_[0]} |
35 | or return; |
36 | } |
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37 | |
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38 | my %spec; |
39 | |
40 | my $bare = 0; |
41 | for my $proto (@_) { |
42 | my $item = ref $proto |
43 | ? $proto |
44 | : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})] |
45 | ; |
46 | my ($name, $type) = @$item; |
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47 | _assert_valid_identifier $name; |
48 | |
49 | unless (ref $type) { |
50 | # use '||' instead of 'or' to preserve $type in the error message |
51 | $type = $type_map{$type} |
52 | || confess qq["$type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})]; |
53 | } |
54 | $type->{name} ||= 'optional'; |
55 | $type->{name} =~ /^(?:optional|required|prohibited)\z/ |
56 | or confess qq["$type->{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)]; |
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57 | if ($type->{shift}) { |
58 | _assert_valid_identifier $type->{shift}, 1; |
59 | bytes::length($type->{shift}) < SHIFT_NAME_LIMIT |
60 | or confess qq["$type->{shift}" is longer than I can handle]; |
61 | } |
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62 | |
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63 | $spec{$name} = $type; |
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64 | } |
65 | |
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66 | for my $kw (keys %spec) { |
67 | my $type = $spec{$kw}; |
68 | |
69 | $^H{HINTK_SHIFT_ . $kw} = $type->{shift} || ''; |
70 | $^H{HINTK_NAME_ . $kw} = |
71 | $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED : |
72 | $type->{name} eq 'required' ? FLAG_NAME_REQUIRED : |
73 | FLAG_NAME_OPTIONAL |
74 | ; |
75 | $^H{+HINTK_KEYWORDS} .= "$kw "; |
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76 | } |
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77 | } |
78 | |
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79 | sub unimport { |
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80 | my $class = shift; |
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81 | |
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82 | if (!@_) { |
83 | delete $^H{+HINTK_KEYWORDS}; |
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84 | return; |
85 | } |
86 | |
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87 | for my $kw (@_) { |
88 | $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g; |
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89 | } |
90 | } |
91 | |
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92 | sub _fini { |
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93 | on_scope_end { |
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94 | xs_fini; |
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95 | }; |
96 | } |
97 | |
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98 | |
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99 | 'ok' |
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100 | |
101 | __END__ |
102 | |
103 | =head1 NAME |
104 | |
105 | Function::Parameters - subroutine definitions with parameter lists |
106 | |
107 | =head1 SYNOPSIS |
108 | |
109 | use Function::Parameters; |
110 | |
111 | fun foo($bar, $baz) { |
112 | return $bar + $baz; |
113 | } |
114 | |
115 | fun mymap($fun, @args) :(&@) { |
116 | my @res; |
117 | for (@args) { |
118 | push @res, $fun->($_); |
119 | } |
120 | @res |
121 | } |
122 | |
123 | print "$_\n" for mymap { $_ * 2 } 1 .. 4; |
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124 | |
125 | method set_name($name) { |
126 | $self->{name} = $name; |
127 | } |
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128 | |
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129 | =cut |
130 | |
131 | =pod |
132 | |
133 | use Function::Parameters 'proc', 'meth'; |
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134 | |
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135 | my $f = proc ($x) { $x * 2 }; |
136 | meth get_age() { |
137 | return $self->{age}; |
138 | } |
139 | |
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140 | =head1 DESCRIPTION |
141 | |
142 | This module lets you use parameter lists in your subroutines. Thanks to |
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143 | L<perlapi/PL_keyword_plugin> it works without source filters. |
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144 | |
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145 | WARNING: This is my first attempt at writing L<XS code|perlxs> and I have |
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146 | almost no experience with perl's internals. So while this module might |
147 | appear to work, it could also conceivably make your programs segfault. |
148 | Consider this module alpha quality. |
149 | |
150 | =head2 Basic stuff |
151 | |
152 | To use this new functionality, you have to use C<fun> instead of C<sub> - |
153 | C<sub> continues to work as before. The syntax is almost the same as for |
154 | C<sub>, but after the subroutine name (or directly after C<fun> if you're |
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155 | writing an anonymous sub) you can write a parameter list in parentheses. This |
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156 | list consists of comma-separated variables. |
157 | |
158 | The effect of C<fun foo($bar, $baz) {> is as if you'd written |
159 | C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply |
160 | copied into C<my> and initialized from L<@_|perlvar/"@_">. |
161 | |
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162 | In addition you can use C<method>, which understands the same syntax as C<fun> |
163 | but automatically creates a C<$self> variable for you. So by writing |
164 | C<method foo($bar, $baz) {> you get the same effect as |
165 | C<sub foo { my $self = shift; my ($bar, $baz) = @_; >. |
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166 | |
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167 | =head2 Customizing the generated keywords |
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168 | |
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169 | You can customize the names of the keywords injected in your package. To do that |
170 | you pass a hash reference in the import list: |
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171 | |
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172 | use Function::Parameters { proc => 'function', meth => 'method' }; # -or- |
173 | use Function::Parameters { proc => 'function' }; # -or- |
174 | use Function::Parameters { meth => 'method' }; |
175 | |
176 | The first line creates two keywords, C<proc> and C<meth> (for defining |
177 | functions and methods, respectively). The last two lines only create one |
178 | keyword. Generally the hash keys can be any identifiers you want while the |
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179 | values have to be either C<function>, C<method>, or a hash reference (see |
180 | below). The difference between C<function> and C<method> is that C<method>s |
181 | automatically L<shift|perlfunc/shift> their first argument into C<$self>. |
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182 | |
183 | The following shortcuts are available: |
184 | |
185 | use Function::Parameters; |
186 | # is equivalent to # |
187 | use Function::Parameters { fun => 'function', method => 'method' }; |
188 | |
189 | =cut |
190 | |
191 | =pod |
192 | |
193 | use Function::Parameters 'foo'; |
194 | # is equivalent to # |
195 | use Function::Parameters { 'foo' => 'function' }; |
196 | |
197 | =cut |
198 | |
199 | =pod |
200 | |
201 | use Function::Parameters 'foo', 'bar'; |
202 | # is equivalent to # |
203 | use Function::Parameters { 'foo' => 'function', 'bar' => 'method' }; |
204 | |
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205 | You can customize things even more by passing a hashref instead of C<function> |
206 | or C<method>. This hash can have the following keys: |
207 | |
208 | =over |
209 | |
210 | =item C<name> |
211 | |
212 | Valid values: C<optional> (default), C<required> (all uses of this keyword must |
213 | specify a function name), and C<prohibited> (all uses of this keyword must not |
214 | specify a function name). This means a C<< name => 'prohibited' >> keyword can |
215 | only be used for defining anonymous functions. |
216 | |
217 | =item C<shift> |
218 | |
219 | Valid values: strings that look like a scalar variable. Any function created by |
220 | this keyword will automatically L<shift|perlfunc/shift> its first argument into |
221 | a local variable with the name specified here. |
222 | |
223 | =back |
224 | |
225 | Plain C<function> is equivalent to C<< { name => 'optional' } >>, and plain |
226 | C<method> is equivalent to C<< { name => 'optional', shift => '$self'} >>. |
227 | |
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228 | =head2 Other advanced stuff |
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229 | |
230 | Normally, Perl subroutines are not in scope in their own body, meaning the |
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231 | parser doesn't know the name C<foo> or its prototype while processing |
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232 | C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as |
233 | C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the |
234 | interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger |
235 | a I<foo() called too early to check prototype> warning. This module attempts |
236 | to fix all of this by adding a subroutine declaration before the definition, |
237 | so the parser knows the name (and possibly prototype) while it processes the |
238 | body. Thus C<fun foo($x) :($) { $x }> really turns into |
239 | C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>. |
240 | |
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241 | If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can |
242 | put them after the parameter list with their usual syntax. |
243 | |
244 | Syntactically, these new parameter lists live in the spot normally occupied |
245 | by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by |
246 | specifying it as the first attribute (this is syntactically unambiguous |
247 | because normal attributes have to start with a letter). |
248 | |
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249 | If you want to wrap L<Function::Parameters>, you just have to call its |
250 | C<import> method. It always applies to the file that is currently being parsed |
251 | and its effects are lexical (i.e. it works like L<warnings> or L<strict>); |
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252 | |
253 | package Some::Wrapper; |
254 | use Function::Parameters (); |
255 | sub import { |
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256 | Function::Parameters->import; |
257 | # or Function::Parameters->import(@other_import_args); |
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258 | } |
259 | |
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260 | =head1 AUTHOR |
261 | |
262 | Lukas Mai, C<< <l.mai at web.de> >> |
263 | |
264 | =head1 COPYRIGHT & LICENSE |
265 | |
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266 | Copyright 2010, 2011, 2012 Lukas Mai. |
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267 | |
268 | This program is free software; you can redistribute it and/or modify it |
269 | under the terms of either: the GNU General Public License as published |
270 | by the Free Software Foundation; or the Artistic License. |
271 | |
272 | See http://dev.perl.org/licenses/ for more information. |
273 | |
274 | =cut |