1 package Function::Parameters;
10 our $VERSION = '0.05_03';
16 sub _assert_valid_identifier {
17 my ($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};
23 sub _assert_valid_attributes {
25 $attrs =~ /^\s*:\s*[^\W\d]\w*\s*(?:(?:\s|:\s*)[^\W\d]\w*\s*)*(?:\(|\z)/
26 or confess qq{"$attrs" doesn't look like valid attributes};
29 my @bare_arms = qw(function method);
31 function => { name => 'optional' },
51 if (@_ == 1 && ref($_[0]) eq 'HASH') {
52 @_ = map [$_, $_[0]{$_}], keys %{$_[0]}
62 : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
64 my ($name, $type) = @$item;
65 _assert_valid_identifier $name;
68 # use '||' instead of 'or' to preserve $type in the error message
69 $type = $type_map{$type}
70 || confess qq["$type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
72 $type->{name} ||= 'optional';
73 $type->{name} =~ /^(?:optional|required|prohibited)\z/
74 or confess qq["$type->{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
76 $type->{shift} and _assert_valid_identifier $type->{shift}, 1;
77 $type->{attrs} and _assert_valid_attributes $type->{attrs};
82 for my $kw (keys %spec) {
83 my $type = $spec{$kw};
85 $^H{HINTK_SHIFT_ . $kw} = $type->{shift} || '';
86 $^H{HINTK_ATTRS_ . $kw} = $type->{attrs} || '';
87 $^H{HINTK_NAME_ . $kw} =
88 $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED :
89 $type->{name} eq 'required' ? FLAG_NAME_REQUIRED :
92 $^H{+HINTK_KEYWORDS} .= "$kw ";
100 delete $^H{+HINTK_KEYWORDS};
105 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
116 Function::Parameters - subroutine definitions with parameter lists
120 use Function::Parameters;
122 fun foo($bar, $baz) {
126 fun mymap($fun, @args) :(&@) {
129 push @res, $fun->($_);
134 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
136 method set_name($name) {
137 $self->{name} = $name;
144 use Function::Parameters {
149 my $f = proc ($x) { $x * 2 };
156 This module lets you use parameter lists in your subroutines. Thanks to
157 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
159 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
160 almost no experience with perl's internals. So while this module might
161 appear to work, it could also conceivably make your programs segfault.
162 Consider this module alpha quality.
166 To use this new functionality, you have to use C<fun> instead of C<sub> -
167 C<sub> continues to work as before. The syntax is almost the same as for
168 C<sub>, but after the subroutine name (or directly after C<fun> if you're
169 writing an anonymous sub) you can write a parameter list in parentheses. This
170 list consists of comma-separated variables.
172 The effect of C<fun foo($bar, $baz) {> is as if you'd written
173 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
174 copied into C<my> and initialized from L<@_|perlvar/"@_">.
176 In addition you can use C<method>, which understands the same syntax as C<fun>
177 but automatically creates a C<$self> variable for you. So by writing
178 C<method foo($bar, $baz) {> you get the same effect as
179 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
181 =head2 Customizing the generated keywords
183 You can customize the names of the keywords injected into your scope. To do
184 that you pass a hash reference in the import list:
186 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
187 use Function::Parameters { proc => 'function' }; # -or-
188 use Function::Parameters { meth => 'method' }; # etc.
190 The first line creates two keywords, C<proc> and C<meth> (for defining
191 functions and methods, respectively). The last two lines only create one
192 keyword. Generally the hash keys can be any identifiers you want while the
193 values have to be either C<function>, C<method>, C<classmethod> or a hash
194 reference (see below). The difference between C<function> and C<method> is that
195 C<method>s automatically L<shift|perlfunc/shift> their first argument into
196 C<$self> (C<classmethod>s are similar but shift into C<$class>).
198 The following shortcuts are available:
200 use Function::Parameters;
202 use Function::Parameters { fun => 'function', method => 'method' };
208 The following shortcuts are deprecated and may be removed from a future version
212 use Function::Parameters 'foo';
214 use Function::Parameters { 'foo' => 'function' };
221 use Function::Parameters 'foo', 'bar';
223 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
225 That is, if you want to pass arguments to L<Function::Parameters>, use a
226 hashref, not a list of strings.
228 You can customize things even more by passing a hashref instead of C<function>
229 or C<method>. This hash can have the following keys:
235 Valid values: C<optional> (default), C<required> (all uses of this keyword must
236 specify a function name), and C<prohibited> (all uses of this keyword must not
237 specify a function name). This means a C<< name => 'prohibited' >> keyword can
238 only be used for defining anonymous functions.
242 Valid values: strings that look like a scalar variable. Any function created by
243 this keyword will automatically L<shift|perlfunc/shift> its first argument into
244 a local variable whose name is specified here.
248 Valid values: strings that are valid source code for attributes. Any value
249 specified here will be inserted as a subroutine attribute in the generated
252 use Function::Parameters { sub_l => { attrs => ':lvalue' } };
265 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, plain
266 C<'method'> is equivalent to
267 C<< { name => 'optional', shift => '$self', attrs => ':method' } >>, and plain
268 C<'classmethod'> is equivalent to
269 C<< { name => 'optional', shift => '$class', attrs => ':method' } >>.
271 =head2 Syntax and generated code
273 Normally, Perl subroutines are not in scope in their own body, meaning the
274 parser doesn't know the name C<foo> or its prototype while processing the body
275 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
276 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
277 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
278 a I<foo() called too early to check prototype> warning. This module attempts
279 to fix all of this by adding a subroutine declaration before the definition,
280 so the parser knows the name (and possibly prototype) while it processes the
281 body. Thus C<fun foo($x) :($) { $x }> really turns into
282 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
284 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
285 put them after the parameter list with their usual syntax.
287 Syntactically, these new parameter lists live in the spot normally occupied
288 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
289 specifying it as the first attribute (this is syntactically unambiguous
290 because normal attributes have to start with a letter while a prototype starts
293 As an example, the following declaration uses every feature available
294 (subroutine name, parameter list, prototype, attributes, and implicit
297 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
301 And here's what it turns into:
303 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
309 my $coderef = fun ($p, $q) :(;$$)
315 And the generated code:
317 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
321 =head2 Wrapping Function::Parameters
323 If you want to wrap L<Function::Parameters>, you just have to call its
324 C<import> method. It always applies to the file that is currently being parsed
325 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
327 package Some::Wrapper;
328 use Function::Parameters ();
330 Function::Parameters->import;
331 # or Function::Parameters->import(@other_import_args);
336 Lukas Mai, C<< <l.mai at web.de> >>
338 =head1 COPYRIGHT & LICENSE
340 Copyright 2010, 2011, 2012 Lukas Mai.
342 This program is free software; you can redistribute it and/or modify it
343 under the terms of either: the GNU General Public License as published
344 by the Free Software Foundation; or the Artistic License.
346 See http://dev.perl.org/licenses/ for more information.