1 package Function::Parameters;
12 our $VERSION = '0.06';
16 sub _assert_valid_identifier {
17 my ($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{"$attrs" doesn't look like valid attributes};
29 my @bare_arms = qw(function method);
33 default_arguments => 1,
34 check_argument_count => 0,
38 default_arguments => 1,
39 check_argument_count => 0,
45 default_arguments => 1,
46 check_argument_count => 0,
59 if (@_ == 1 && ref($_[0]) eq 'HASH') {
60 @_ = map [$_, $_[0]{$_}], keys %{$_[0]}
70 : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
72 my ($name, $proto_type) = @$item;
73 _assert_valid_identifier $name;
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 ${\join ', ', sort keys %type_map})];
81 my %type = %$proto_type;
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)];
88 $clean{shift} = delete $type{shift} || '';
89 _assert_valid_identifier $clean{shift}, 1 if $clean{shift};
91 $clean{attrs} = delete $type{attrs} || '';
92 _assert_valid_attributes $clean{attrs} if $clean{attrs};
94 $clean{default_arguments} = !!delete $type{default_arguments};
95 $clean{check_argument_count} = !!delete $type{check_argument_count};
97 %type and confess "Invalid keyword property: @{[keys %type]}";
99 $spec{$name} = \%clean;
102 for my $kw (keys %spec) {
103 my $type = $spec{$kw};
106 $type->{name} eq 'prohibited' ? FLAG_ANON_OK :
107 $type->{name} eq 'required' ? FLAG_NAME_OK :
108 FLAG_ANON_OK | FLAG_NAME_OK
110 $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments};
111 $flags |= FLAG_CHECK_NARGS if $type->{check_argument_count};
112 $^H{HINTK_FLAGS_ . $kw} = $flags;
113 $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
114 $^H{HINTK_ATTRS_ . $kw} = $type->{attrs};
115 $^H{+HINTK_KEYWORDS} .= "$kw ";
123 delete $^H{+HINTK_KEYWORDS};
128 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
141 Function::Parameters - subroutine definitions with parameter lists
145 use Function::Parameters;
147 fun foo($bar, $baz) {
151 fun mymap($fun, @args) :(&@) {
154 push @res, $fun->($_);
159 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
161 method set_name($name) {
162 $self->{name} = $name;
169 use Function::Parameters {
174 my $f = proc ($x) { $x * 2 };
181 This module lets you use parameter lists in your subroutines. Thanks to
182 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
184 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
185 almost no experience with perl's internals. So while this module might
186 appear to work, it could also conceivably make your programs segfault.
187 Consider this module alpha quality.
191 To use this new functionality, you have to use C<fun> instead of C<sub> -
192 C<sub> continues to work as before. The syntax is almost the same as for
193 C<sub>, but after the subroutine name (or directly after C<fun> if you're
194 writing an anonymous sub) you can write a parameter list in parentheses. This
195 list consists of comma-separated variables.
197 The effect of C<fun foo($bar, $baz) {> is as if you'd written
198 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
199 copied into C<my> and initialized from L<@_|perlvar/"@_">.
201 In addition you can use C<method>, which understands the same syntax as C<fun>
202 but automatically creates a C<$self> variable for you. So by writing
203 C<method foo($bar, $baz) {> you get the same effect as
204 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
206 =head2 Customizing the generated keywords
208 You can customize the names of the keywords injected into your scope. To do
209 that you pass a hash reference in the import list:
211 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
212 use Function::Parameters { proc => 'function' }; # -or-
213 use Function::Parameters { meth => 'method' }; # etc.
215 The first line creates two keywords, C<proc> and C<meth> (for defining
216 functions and methods, respectively). The last two lines only create one
217 keyword. Generally the hash keys can be any identifiers you want while the
218 values have to be either C<function>, C<method>, C<classmethod> or a hash
219 reference (see below). The difference between C<function> and C<method> is that
220 C<method>s automatically L<shift|perlfunc/shift> their first argument into
221 C<$self> (C<classmethod>s are similar but shift into C<$class>).
223 The following shortcuts are available:
225 use Function::Parameters;
227 use Function::Parameters { fun => 'function', method => 'method' };
233 The following shortcuts are deprecated and may be removed from a future version
237 use Function::Parameters 'foo';
239 use Function::Parameters { 'foo' => 'function' };
246 use Function::Parameters 'foo', 'bar';
248 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
250 That is, if you want to pass arguments to L<Function::Parameters>, use a
251 hashref, not a list of strings.
253 You can customize things even more by passing a hashref instead of C<function>
254 or C<method>. This hash can have the following keys:
260 Valid values: C<optional> (default), C<required> (all uses of this keyword must
261 specify a function name), and C<prohibited> (all uses of this keyword must not
262 specify a function name). This means a C<< name => 'prohibited' >> keyword can
263 only be used for defining anonymous functions.
267 Valid values: strings that look like a scalar variable. Any function created by
268 this keyword will automatically L<shift|perlfunc/shift> its first argument into
269 a local variable whose name is specified here.
273 Valid values: strings that are valid source code for attributes. Any value
274 specified here will be inserted as a subroutine attribute in the generated
277 use Function::Parameters { sub_l => { attrs => ':lvalue' } };
290 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, plain
291 C<'method'> is equivalent to
292 C<< { name => 'optional', shift => '$self', attrs => ':method' } >>, and plain
293 C<'classmethod'> is equivalent to
294 C<< { name => 'optional', shift => '$class', attrs => ':method' } >>.
296 =head2 Syntax and generated code
298 Normally, Perl subroutines are not in scope in their own body, meaning the
299 parser doesn't know the name C<foo> or its prototype while processing the body
300 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
301 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
302 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
303 a I<foo() called too early to check prototype> warning. This module attempts
304 to fix all of this by adding a subroutine declaration before the definition,
305 so the parser knows the name (and possibly prototype) while it processes the
306 body. Thus C<fun foo($x) :($) { $x }> really turns into
307 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
309 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
310 put them after the parameter list with their usual syntax.
312 Syntactically, these new parameter lists live in the spot normally occupied
313 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
314 specifying it as the first attribute (this is syntactically unambiguous
315 because normal attributes have to start with a letter while a prototype starts
318 As an example, the following declaration uses every feature available
319 (subroutine name, parameter list, prototype, attributes, and implicit
322 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
326 And here's what it turns into:
328 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
334 my $coderef = fun ($p, $q) :(;$$)
340 And the generated code:
342 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
346 =head2 Wrapping Function::Parameters
348 If you want to wrap L<Function::Parameters>, you just have to call its
349 C<import> method. It always applies to the file that is currently being parsed
350 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
352 package Some::Wrapper;
353 use Function::Parameters ();
355 Function::Parameters->import;
356 # or Function::Parameters->import(@other_import_args);
361 Lukas Mai, C<< <l.mai at web.de> >>
363 =head1 COPYRIGHT & LICENSE
365 Copyright 2010, 2011, 2012 Lukas Mai.
367 This program is free software; you can redistribute it and/or modify it
368 under the terms of either: the GNU General Public License as published
369 by the Free Software Foundation; or the Artistic License.
371 See http://dev.perl.org/licenses/ for more information.