1 package Function::Parameters;
10 our $VERSION = '0.05_02';
14 use B::Hooks::EndOfScope qw(on_scope_end);
18 sub _assert_valid_identifier {
19 my ($name, $with_dollar) = @_;
20 my $bonus = $with_dollar ? '\$' : '';
21 $name =~ /^${bonus}[^\W\d]\w*\z/
22 or confess qq{"$name" doesn't look like a valid identifier};
25 my @bare_arms = qw(function method);
27 function => { name => 'optional' },
28 method => { name => 'optional', shift => '$self' },
34 @_ or @_ = ('fun', 'method');
35 if (@_ == 1 && ref($_[0]) eq 'HASH') {
36 @_ = map [$_, $_[0]{$_}], keys %{$_[0]}
46 : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
48 my ($name, $type) = @$item;
49 _assert_valid_identifier $name;
52 # use '||' instead of 'or' to preserve $type in the error message
53 $type = $type_map{$type}
54 || confess qq["$type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
56 $type->{name} ||= 'optional';
57 $type->{name} =~ /^(?:optional|required|prohibited)\z/
58 or confess qq["$type->{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
60 _assert_valid_identifier $type->{shift}, 1;
61 bytes::length($type->{shift}) < SHIFT_NAME_LIMIT
62 or confess qq["$type->{shift}" is longer than I can handle];
68 for my $kw (keys %spec) {
69 my $type = $spec{$kw};
71 $^H{HINTK_SHIFT_ . $kw} = $type->{shift} || '';
72 $^H{HINTK_NAME_ . $kw} =
73 $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED :
74 $type->{name} eq 'required' ? FLAG_NAME_REQUIRED :
77 $^H{+HINTK_KEYWORDS} .= "$kw ";
85 delete $^H{+HINTK_KEYWORDS};
90 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
107 Function::Parameters - subroutine definitions with parameter lists
111 use Function::Parameters;
113 fun foo($bar, $baz) {
117 fun mymap($fun, @args) :(&@) {
120 push @res, $fun->($_);
125 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
127 method set_name($name) {
128 $self->{name} = $name;
135 use Function::Parameters 'proc', 'meth';
137 my $f = proc ($x) { $x * 2 };
144 This module lets you use parameter lists in your subroutines. Thanks to
145 L<perlapi/PL_keyword_plugin> it works without source filters.
147 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
148 almost no experience with perl's internals. So while this module might
149 appear to work, it could also conceivably make your programs segfault.
150 Consider this module alpha quality.
154 To use this new functionality, you have to use C<fun> instead of C<sub> -
155 C<sub> continues to work as before. The syntax is almost the same as for
156 C<sub>, but after the subroutine name (or directly after C<fun> if you're
157 writing an anonymous sub) you can write a parameter list in parentheses. This
158 list consists of comma-separated variables.
160 The effect of C<fun foo($bar, $baz) {> is as if you'd written
161 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
162 copied into C<my> and initialized from L<@_|perlvar/"@_">.
164 In addition you can use C<method>, which understands the same syntax as C<fun>
165 but automatically creates a C<$self> variable for you. So by writing
166 C<method foo($bar, $baz) {> you get the same effect as
167 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
169 =head2 Customizing the generated keywords
171 You can customize the names of the keywords injected in your package. To do that
172 you pass a hash reference in the import list:
174 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
175 use Function::Parameters { proc => 'function' }; # -or-
176 use Function::Parameters { meth => 'method' };
178 The first line creates two keywords, C<proc> and C<meth> (for defining
179 functions and methods, respectively). The last two lines only create one
180 keyword. Generally the hash keys can be any identifiers you want while the
181 values have to be either C<function>, C<method>, or a hash reference (see
182 below). The difference between C<function> and C<method> is that C<method>s
183 automatically L<shift|perlfunc/shift> their first argument into C<$self>.
185 The following shortcuts are available:
187 use Function::Parameters;
189 use Function::Parameters { fun => 'function', method => 'method' };
195 use Function::Parameters 'foo';
197 use Function::Parameters { 'foo' => 'function' };
203 use Function::Parameters 'foo', 'bar';
205 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
207 You can customize things even more by passing a hashref instead of C<function>
208 or C<method>. This hash can have the following keys:
214 Valid values: C<optional> (default), C<required> (all uses of this keyword must
215 specify a function name), and C<prohibited> (all uses of this keyword must not
216 specify a function name). This means a C<< name => 'prohibited' >> keyword can
217 only be used for defining anonymous functions.
221 Valid values: strings that look like a scalar variable. Any function created by
222 this keyword will automatically L<shift|perlfunc/shift> its first argument into
223 a local variable with the name specified here.
227 Plain C<function> is equivalent to C<< { name => 'optional' } >>, and plain
228 C<method> is equivalent to C<< { name => 'optional', shift => '$self'} >>.
230 =head2 Other advanced stuff
232 Normally, Perl subroutines are not in scope in their own body, meaning the
233 parser doesn't know the name C<foo> or its prototype while processing
234 C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
235 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
236 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
237 a I<foo() called too early to check prototype> warning. This module attempts
238 to fix all of this by adding a subroutine declaration before the definition,
239 so the parser knows the name (and possibly prototype) while it processes the
240 body. Thus C<fun foo($x) :($) { $x }> really turns into
241 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
243 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
244 put them after the parameter list with their usual syntax.
246 Syntactically, these new parameter lists live in the spot normally occupied
247 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
248 specifying it as the first attribute (this is syntactically unambiguous
249 because normal attributes have to start with a letter).
251 If you want to wrap L<Function::Parameters>, you just have to call its
252 C<import> method. It always applies to the file that is currently being parsed
253 and its effects are lexical (i.e. it works like L<warnings> or L<strict>);
255 package Some::Wrapper;
256 use Function::Parameters ();
258 Function::Parameters->import;
259 # or Function::Parameters->import(@other_import_args);
264 Lukas Mai, C<< <l.mai at web.de> >>
266 =head1 COPYRIGHT & LICENSE
268 Copyright 2010, 2011, 2012 Lukas Mai.
270 This program is free software; you can redistribute it and/or modify it
271 under the terms of either: the GNU General Public License as published
272 by the Free Software Foundation; or the Artistic License.
274 See http://dev.perl.org/licenses/ for more information.