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{"$attrs" doesn't look like valid attributes};
29 my @bare_arms = qw(function method);
31 function => { name => 'optional' },
46 if (@_ == 1 && ref($_[0]) eq 'HASH') {
47 @_ = map [$_, $_[0]{$_}], keys %{$_[0]}
57 : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
59 my ($name, $proto_type) = @$item;
60 _assert_valid_identifier $name;
62 unless (ref $proto_type) {
63 # use '||' instead of 'or' to preserve $proto_type in the error message
64 $proto_type = $type_map{$proto_type}
65 || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
68 my %type = %$proto_type;
71 $clean{name} = delete $type{name} || 'optional';
72 $clean{name} =~ /^(?:optional|required|prohibited)\z/
73 or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
75 $clean{shift} = delete $type{shift} || '';
76 _assert_valid_identifier $clean{shift}, 1 if $clean{shift};
78 $clean{attrs} = delete $type{attrs} || '';
79 _assert_valid_attributes $clean{attrs} if $clean{attrs};
81 %type and confess "Invalid keyword property: @{[keys %type]}";
83 $spec{$name} = \%clean;
86 for my $kw (keys %spec) {
87 my $type = $spec{$kw};
89 $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
90 $^H{HINTK_ATTRS_ . $kw} = $type->{attrs};
91 $^H{HINTK_NAME_ . $kw} =
92 $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED :
93 $type->{name} eq 'required' ? FLAG_NAME_REQUIRED :
96 $^H{+HINTK_KEYWORDS} .= "$kw ";
104 delete $^H{+HINTK_KEYWORDS};
109 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
120 Function::Parameters - subroutine definitions with parameter lists
124 use Function::Parameters;
126 fun foo($bar, $baz) {
130 fun mymap($fun, @args) :(&@) {
133 push @res, $fun->($_);
138 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
140 method set_name($name) {
141 $self->{name} = $name;
148 use Function::Parameters {
153 my $f = proc ($x) { $x * 2 };
160 This module lets you use parameter lists in your subroutines. Thanks to
161 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
163 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
164 almost no experience with perl's internals. So while this module might
165 appear to work, it could also conceivably make your programs segfault.
166 Consider this module alpha quality.
170 To use this new functionality, you have to use C<fun> instead of C<sub> -
171 C<sub> continues to work as before. The syntax is almost the same as for
172 C<sub>, but after the subroutine name (or directly after C<fun> if you're
173 writing an anonymous sub) you can write a parameter list in parentheses. This
174 list consists of comma-separated variables.
176 The effect of C<fun foo($bar, $baz) {> is as if you'd written
177 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
178 copied into C<my> and initialized from L<@_|perlvar/"@_">.
180 In addition you can use C<method>, which understands the same syntax as C<fun>
181 but automatically creates a C<$self> variable for you. So by writing
182 C<method foo($bar, $baz) {> you get the same effect as
183 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
185 =head2 Customizing the generated keywords
187 You can customize the names of the keywords injected into your scope. To do
188 that you pass a hash reference in the import list:
190 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
191 use Function::Parameters { proc => 'function' }; # -or-
192 use Function::Parameters { meth => 'method' };
194 The first line creates two keywords, C<proc> and C<meth> (for defining
195 functions and methods, respectively). The last two lines only create one
196 keyword. Generally the hash keys can be any identifiers you want while the
197 values have to be either C<function>, C<method>, or a hash reference (see
198 below). The difference between C<function> and C<method> is that C<method>s
199 automatically L<shift|perlfunc/shift> their first argument into C<$self>.
201 The following shortcuts are available:
203 use Function::Parameters;
205 use Function::Parameters { fun => 'function', method => 'method' };
211 The following shortcuts are deprecated and may be removed from a future version
215 use Function::Parameters 'foo';
217 use Function::Parameters { 'foo' => 'function' };
224 use Function::Parameters 'foo', 'bar';
226 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
228 That is, if you want to pass arguments to L<Function::Parameters>, use a
229 hashref, not a list of strings.
231 You can customize things even more by passing a hashref instead of C<function>
232 or C<method>. This hash can have the following keys:
238 Valid values: C<optional> (default), C<required> (all uses of this keyword must
239 specify a function name), and C<prohibited> (all uses of this keyword must not
240 specify a function name). This means a C<< name => 'prohibited' >> keyword can
241 only be used for defining anonymous functions.
245 Valid values: strings that look like a scalar variable. Any function created by
246 this keyword will automatically L<shift|perlfunc/shift> its first argument into
247 a local variable whose name is specified here.
251 Valid values: strings that are valid source code for attributes. Any value
252 specified here will be inserted as a subroutine attribute in the generated
255 use Function::Parameters { sub_l => { attrs => ':lvalue' } };
268 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, and plain
269 C<'method'> is equivalent to
270 C<< { name => 'optional', shift => '$self', attrs => ':method' } >>.
272 =head2 Syntax and generated code
274 Normally, Perl subroutines are not in scope in their own body, meaning the
275 parser doesn't know the name C<foo> or its prototype while processing the body
276 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
277 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
278 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
279 a I<foo() called too early to check prototype> warning. This module attempts
280 to fix all of this by adding a subroutine declaration before the definition,
281 so the parser knows the name (and possibly prototype) while it processes the
282 body. Thus C<fun foo($x) :($) { $x }> really turns into
283 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
285 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
286 put them after the parameter list with their usual syntax.
288 Syntactically, these new parameter lists live in the spot normally occupied
289 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
290 specifying it as the first attribute (this is syntactically unambiguous
291 because normal attributes have to start with a letter while a prototype starts
294 As an example, the following declaration uses every feature available
295 (subroutine name, parameter list, prototype, attributes, and implicit
298 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
302 And here's what it turns into:
304 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
310 my $coderef = fun ($p, $q) :(;$$)
316 And the generated code:
318 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
322 =head2 Wrapping Function::Parameters
324 If you want to wrap L<Function::Parameters>, you just have to call its
325 C<import> method. It always applies to the file that is currently being parsed
326 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
328 package Some::Wrapper;
329 use Function::Parameters ();
331 Function::Parameters->import;
332 # or Function::Parameters->import(@other_import_args);
337 Lukas Mai, C<< <l.mai at web.de> >>
339 =head1 COPYRIGHT & LICENSE
341 Copyright 2010, 2011, 2012 Lukas Mai.
343 This program is free software; you can redistribute it and/or modify it
344 under the terms of either: the GNU General Public License as published
345 by the Free Software Foundation; or the Artistic License.
347 See http://dev.perl.org/licenses/ for more information.