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} =
95 exists $type{default_arguments}
96 ? !!delete $type{default_arguments}
99 $clean{check_argument_count} = !!delete $type{check_argument_count};
101 %type and confess "Invalid keyword property: @{[keys %type]}";
103 $spec{$name} = \%clean;
106 for my $kw (keys %spec) {
107 my $type = $spec{$kw};
110 $type->{name} eq 'prohibited' ? FLAG_ANON_OK :
111 $type->{name} eq 'required' ? FLAG_NAME_OK :
112 FLAG_ANON_OK | FLAG_NAME_OK
114 $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments};
115 $flags |= FLAG_CHECK_NARGS if $type->{check_argument_count};
116 $^H{HINTK_FLAGS_ . $kw} = $flags;
117 $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
118 $^H{HINTK_ATTRS_ . $kw} = $type->{attrs};
119 $^H{+HINTK_KEYWORDS} .= "$kw ";
127 delete $^H{+HINTK_KEYWORDS};
132 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
145 Function::Parameters - subroutine definitions with parameter lists
149 use Function::Parameters;
151 fun foo($bar, $baz) {
155 fun mymap($fun, @args) :(&@) {
158 push @res, $fun->($_);
163 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
165 method set_name($name) {
166 $self->{name} = $name;
173 use Function::Parameters {
178 my $f = proc ($x) { $x * 2 };
185 This module lets you use parameter lists in your subroutines. Thanks to
186 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
188 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
189 almost no experience with perl's internals. So while this module might
190 appear to work, it could also conceivably make your programs segfault.
191 Consider this module alpha quality.
195 To use this new functionality, you have to use C<fun> instead of C<sub> -
196 C<sub> continues to work as before. The syntax is almost the same as for
197 C<sub>, but after the subroutine name (or directly after C<fun> if you're
198 writing an anonymous sub) you can write a parameter list in parentheses. This
199 list consists of comma-separated variables.
201 The effect of C<fun foo($bar, $baz) {> is as if you'd written
202 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
203 copied into C<my> and initialized from L<@_|perlvar/"@_">.
205 In addition you can use C<method>, which understands the same syntax as C<fun>
206 but automatically creates a C<$self> variable for you. So by writing
207 C<method foo($bar, $baz) {> you get the same effect as
208 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
210 =head2 Customizing the generated keywords
212 You can customize the names of the keywords injected into your scope. To do
213 that you pass a hash reference in the import list:
215 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
216 use Function::Parameters { proc => 'function' }; # -or-
217 use Function::Parameters { meth => 'method' }; # etc.
219 The first line creates two keywords, C<proc> and C<meth> (for defining
220 functions and methods, respectively). The last two lines only create one
221 keyword. Generally the hash keys can be any identifiers you want while the
222 values have to be either C<function>, C<method>, C<classmethod> or a hash
223 reference (see below). The difference between C<function> and C<method> is that
224 C<method>s automatically L<shift|perlfunc/shift> their first argument into
225 C<$self> (C<classmethod>s are similar but shift into C<$class>).
227 The following shortcuts are available:
229 use Function::Parameters;
231 use Function::Parameters { fun => 'function', method => 'method' };
237 The following shortcuts are deprecated and may be removed from a future version
241 use Function::Parameters 'foo';
243 use Function::Parameters { 'foo' => 'function' };
250 use Function::Parameters 'foo', 'bar';
252 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
254 That is, if you want to pass arguments to L<Function::Parameters>, use a
255 hashref, not a list of strings.
257 You can customize things even more by passing a hashref instead of C<function>
258 or C<method>. This hash can have the following keys:
264 Valid values: C<optional> (default), C<required> (all uses of this keyword must
265 specify a function name), and C<prohibited> (all uses of this keyword must not
266 specify a function name). This means a C<< name => 'prohibited' >> keyword can
267 only be used for defining anonymous functions.
271 Valid values: strings that look like a scalar variable. Any function created by
272 this keyword will automatically L<shift|perlfunc/shift> its first argument into
273 a local variable whose name is specified here.
277 Valid values: strings that are valid source code for attributes. Any value
278 specified here will be inserted as a subroutine attribute in the generated
281 use Function::Parameters { sub_l => { attrs => ':lvalue' } };
294 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, plain
295 C<'method'> is equivalent to
296 C<< { name => 'optional', shift => '$self', attrs => ':method' } >>, and plain
297 C<'classmethod'> is equivalent to
298 C<< { name => 'optional', shift => '$class', attrs => ':method' } >>.
300 =head2 Syntax and generated code
302 Normally, Perl subroutines are not in scope in their own body, meaning the
303 parser doesn't know the name C<foo> or its prototype while processing the body
304 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
305 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
306 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
307 a I<foo() called too early to check prototype> warning. This module attempts
308 to fix all of this by adding a subroutine declaration before the definition,
309 so the parser knows the name (and possibly prototype) while it processes the
310 body. Thus C<fun foo($x) :($) { $x }> really turns into
311 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
313 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
314 put them after the parameter list with their usual syntax.
316 Syntactically, these new parameter lists live in the spot normally occupied
317 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
318 specifying it as the first attribute (this is syntactically unambiguous
319 because normal attributes have to start with a letter while a prototype starts
322 As an example, the following declaration uses every feature available
323 (subroutine name, parameter list, prototype, attributes, and implicit
326 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
330 And here's what it turns into:
332 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
338 my $coderef = fun ($p, $q) :(;$$)
344 And the generated code:
346 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
350 =head2 Wrapping Function::Parameters
352 If you want to wrap L<Function::Parameters>, you just have to call its
353 C<import> method. It always applies to the file that is currently being parsed
354 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
356 package Some::Wrapper;
357 use Function::Parameters ();
359 Function::Parameters->import;
360 # or Function::Parameters->import(@other_import_args);
365 Lukas Mai, C<< <l.mai at web.de> >>
367 =head1 COPYRIGHT & LICENSE
369 Copyright 2010, 2011, 2012 Lukas Mai.
371 This program is free software; you can redistribute it and/or modify it
372 under the terms of either: the GNU General Public License as published
373 by the Free Software Foundation; or the Artistic License.
375 See http://dev.perl.org/licenses/ for more information.