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, $proto_type) = @$item;
65 _assert_valid_identifier $name;
67 unless (ref $proto_type) {
68 # use '||' instead of 'or' to preserve $proto_type in the error message
69 $proto_type = $type_map{$proto_type}
70 || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
73 my %type = %$proto_type;
76 $clean{name} = delete $type{name} || 'optional';
77 $clean{name} =~ /^(?:optional|required|prohibited)\z/
78 or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
80 $clean{shift} = delete $type{shift} || '';
81 _assert_valid_identifier $clean{shift}, 1 if $clean{shift};
83 $clean{attrs} = delete $type{attrs} || '';
84 _assert_valid_attributes $clean{attrs} if $clean{attrs};
86 %type and confess "Invalid keyword property: @{[keys %type]}";
88 $spec{$name} = \%clean;
91 for my $kw (keys %spec) {
92 my $type = $spec{$kw};
94 $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
95 $^H{HINTK_ATTRS_ . $kw} = $type->{attrs};
96 $^H{HINTK_NAME_ . $kw} =
97 $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED :
98 $type->{name} eq 'required' ? FLAG_NAME_REQUIRED :
101 $^H{+HINTK_KEYWORDS} .= "$kw ";
109 delete $^H{+HINTK_KEYWORDS};
114 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
125 Function::Parameters - subroutine definitions with parameter lists
129 use Function::Parameters;
131 fun foo($bar, $baz) {
135 fun mymap($fun, @args) :(&@) {
138 push @res, $fun->($_);
143 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
145 method set_name($name) {
146 $self->{name} = $name;
153 use Function::Parameters {
158 my $f = proc ($x) { $x * 2 };
165 This module lets you use parameter lists in your subroutines. Thanks to
166 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
168 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
169 almost no experience with perl's internals. So while this module might
170 appear to work, it could also conceivably make your programs segfault.
171 Consider this module alpha quality.
175 To use this new functionality, you have to use C<fun> instead of C<sub> -
176 C<sub> continues to work as before. The syntax is almost the same as for
177 C<sub>, but after the subroutine name (or directly after C<fun> if you're
178 writing an anonymous sub) you can write a parameter list in parentheses. This
179 list consists of comma-separated variables.
181 The effect of C<fun foo($bar, $baz) {> is as if you'd written
182 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
183 copied into C<my> and initialized from L<@_|perlvar/"@_">.
185 In addition you can use C<method>, which understands the same syntax as C<fun>
186 but automatically creates a C<$self> variable for you. So by writing
187 C<method foo($bar, $baz) {> you get the same effect as
188 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
190 =head2 Customizing the generated keywords
192 You can customize the names of the keywords injected into your scope. To do
193 that you pass a hash reference in the import list:
195 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
196 use Function::Parameters { proc => 'function' }; # -or-
197 use Function::Parameters { meth => 'method' }; # etc.
199 The first line creates two keywords, C<proc> and C<meth> (for defining
200 functions and methods, respectively). The last two lines only create one
201 keyword. Generally the hash keys can be any identifiers you want while the
202 values have to be either C<function>, C<method>, C<classmethod> or a hash
203 reference (see below). The difference between C<function> and C<method> is that
204 C<method>s automatically L<shift|perlfunc/shift> their first argument into
205 C<$self> (C<classmethod>s are similar but shift into C<$class>).
207 The following shortcuts are available:
209 use Function::Parameters;
211 use Function::Parameters { fun => 'function', method => 'method' };
217 The following shortcuts are deprecated and may be removed from a future version
221 use Function::Parameters 'foo';
223 use Function::Parameters { 'foo' => 'function' };
230 use Function::Parameters 'foo', 'bar';
232 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
234 That is, if you want to pass arguments to L<Function::Parameters>, use a
235 hashref, not a list of strings.
237 You can customize things even more by passing a hashref instead of C<function>
238 or C<method>. This hash can have the following keys:
244 Valid values: C<optional> (default), C<required> (all uses of this keyword must
245 specify a function name), and C<prohibited> (all uses of this keyword must not
246 specify a function name). This means a C<< name => 'prohibited' >> keyword can
247 only be used for defining anonymous functions.
251 Valid values: strings that look like a scalar variable. Any function created by
252 this keyword will automatically L<shift|perlfunc/shift> its first argument into
253 a local variable whose name is specified here.
257 Valid values: strings that are valid source code for attributes. Any value
258 specified here will be inserted as a subroutine attribute in the generated
261 use Function::Parameters { sub_l => { attrs => ':lvalue' } };
274 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, plain
275 C<'method'> is equivalent to
276 C<< { name => 'optional', shift => '$self', attrs => ':method' } >>, and plain
277 C<'classmethod'> is equivalent to
278 C<< { name => 'optional', shift => '$class', attrs => ':method' } >>.
280 =head2 Syntax and generated code
282 Normally, Perl subroutines are not in scope in their own body, meaning the
283 parser doesn't know the name C<foo> or its prototype while processing the body
284 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
285 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
286 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
287 a I<foo() called too early to check prototype> warning. This module attempts
288 to fix all of this by adding a subroutine declaration before the definition,
289 so the parser knows the name (and possibly prototype) while it processes the
290 body. Thus C<fun foo($x) :($) { $x }> really turns into
291 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
293 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
294 put them after the parameter list with their usual syntax.
296 Syntactically, these new parameter lists live in the spot normally occupied
297 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
298 specifying it as the first attribute (this is syntactically unambiguous
299 because normal attributes have to start with a letter while a prototype starts
302 As an example, the following declaration uses every feature available
303 (subroutine name, parameter list, prototype, attributes, and implicit
306 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
310 And here's what it turns into:
312 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
318 my $coderef = fun ($p, $q) :(;$$)
324 And the generated code:
326 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
330 =head2 Wrapping Function::Parameters
332 If you want to wrap L<Function::Parameters>, you just have to call its
333 C<import> method. It always applies to the file that is currently being parsed
334 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
336 package Some::Wrapper;
337 use Function::Parameters ();
339 Function::Parameters->import;
340 # or Function::Parameters->import(@other_import_args);
345 Lukas Mai, C<< <l.mai at web.de> >>
347 =head1 COPYRIGHT & LICENSE
349 Copyright 2010, 2011, 2012 Lukas Mai.
351 This program is free software; you can redistribute it and/or modify it
352 under the terms of either: the GNU General Public License as published
353 by the Free Software Foundation; or the Artistic License.
355 See http://dev.perl.org/licenses/ for more information.