1 package Function::Parameters;
10 our $VERSION = '0.05_03';
17 sub _assert_valid_identifier {
18 my ($name, $with_dollar) = @_;
19 my $bonus = $with_dollar ? '\$' : '';
20 $name =~ /^${bonus}[^\W\d]\w*\z/
21 or confess qq{"$name" doesn't look like a valid identifier};
24 my @bare_arms = qw(function method);
26 function => { name => 'optional' },
27 method => { name => 'optional', shift => '$self' },
33 @_ or @_ = ('fun', 'method');
34 if (@_ == 1 && ref($_[0]) eq 'HASH') {
35 @_ = map [$_, $_[0]{$_}], keys %{$_[0]}
45 : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
47 my ($name, $proto_type) = @$item;
48 _assert_valid_identifier $name;
50 unless (ref $proto_type) {
51 # use '||' instead of 'or' to preserve $proto_type in the error message
52 $proto_type = $type_map{$proto_type}
53 || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
55 my %type = %$proto_type;
57 $clean{name} = delete $type{name} || 'optional';
58 $clean{name} =~ /^(?:optional|required|prohibited)\z/
59 or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
60 $clean{shift} = delete $type{shift} || '';
62 _assert_valid_identifier $clean{shift}, 1;
63 bytes::length($clean{shift}) < SHIFT_NAME_LIMIT
64 or confess qq["$clean{shift}" is longer than I can handle];
67 %type and confess "Invalid keyword property: @{[keys %type]}";
69 $spec{$name} = \%clean;
72 for my $kw (keys %spec) {
73 my $type = $spec{$kw};
75 $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
76 $^H{HINTK_NAME_ . $kw} =
77 $type->{name} eq 'prohibited' ? FLAG_NAME_PROHIBITED :
78 $type->{name} eq 'required' ? FLAG_NAME_REQUIRED :
81 $^H{+HINTK_KEYWORDS} .= "$kw ";
89 delete $^H{+HINTK_KEYWORDS};
94 $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
105 Function::Parameters - subroutine definitions with parameter lists
109 use Function::Parameters;
111 fun foo($bar, $baz) {
115 fun mymap($fun, @args) :(&@) {
118 push @res, $fun->($_);
123 print "$_\n" for mymap { $_ * 2 } 1 .. 4;
125 method set_name($name) {
126 $self->{name} = $name;
133 use Function::Parameters {
138 my $f = proc ($x) { $x * 2 };
145 This module lets you use parameter lists in your subroutines. Thanks to
146 L<PL_keyword_plugin|perlapi/PL_keyword_plugin> it works without source filters.
148 WARNING: This is my first attempt at writing L<XS code|perlxs> and I have
149 almost no experience with perl's internals. So while this module might
150 appear to work, it could also conceivably make your programs segfault.
151 Consider this module alpha quality.
155 To use this new functionality, you have to use C<fun> instead of C<sub> -
156 C<sub> continues to work as before. The syntax is almost the same as for
157 C<sub>, but after the subroutine name (or directly after C<fun> if you're
158 writing an anonymous sub) you can write a parameter list in parentheses. This
159 list consists of comma-separated variables.
161 The effect of C<fun foo($bar, $baz) {> is as if you'd written
162 C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
163 copied into C<my> and initialized from L<@_|perlvar/"@_">.
165 In addition you can use C<method>, which understands the same syntax as C<fun>
166 but automatically creates a C<$self> variable for you. So by writing
167 C<method foo($bar, $baz) {> you get the same effect as
168 C<sub foo { my $self = shift; my ($bar, $baz) = @_; >.
170 =head2 Customizing the generated keywords
172 You can customize the names of the keywords injected into your scope. To do
173 that you pass a hash reference in the import list:
175 use Function::Parameters { proc => 'function', meth => 'method' }; # -or-
176 use Function::Parameters { proc => 'function' }; # -or-
177 use Function::Parameters { meth => 'method' };
179 The first line creates two keywords, C<proc> and C<meth> (for defining
180 functions and methods, respectively). The last two lines only create one
181 keyword. Generally the hash keys can be any identifiers you want while the
182 values have to be either C<function>, C<method>, or a hash reference (see
183 below). The difference between C<function> and C<method> is that C<method>s
184 automatically L<shift|perlfunc/shift> their first argument into C<$self>.
186 The following shortcuts are available:
188 use Function::Parameters;
190 use Function::Parameters { fun => 'function', method => 'method' };
196 The following shortcuts are deprecated and may be removed from a future version
200 use Function::Parameters 'foo';
202 use Function::Parameters { 'foo' => 'function' };
209 use Function::Parameters 'foo', 'bar';
211 use Function::Parameters { 'foo' => 'function', 'bar' => 'method' };
213 That is, if you want to pass arguments to L<Function::Parameters>, use a
214 hashref, not a list of strings.
216 You can customize things even more by passing a hashref instead of C<function>
217 or C<method>. This hash can have the following keys:
223 Valid values: C<optional> (default), C<required> (all uses of this keyword must
224 specify a function name), and C<prohibited> (all uses of this keyword must not
225 specify a function name). This means a C<< name => 'prohibited' >> keyword can
226 only be used for defining anonymous functions.
230 Valid values: strings that look like a scalar variable. Any function created by
231 this keyword will automatically L<shift|perlfunc/shift> its first argument into
232 a local variable whose name is specified here.
236 Plain C<'function'> is equivalent to C<< { name => 'optional' } >>, and plain
237 C<'method'> is equivalent to C<< { name => 'optional', shift => '$self' } >>.
239 =head2 Syntax and generated code
241 Normally, Perl subroutines are not in scope in their own body, meaning the
242 parser doesn't know the name C<foo> or its prototype while processing the body
243 of C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
244 C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
245 interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
246 a I<foo() called too early to check prototype> warning. This module attempts
247 to fix all of this by adding a subroutine declaration before the definition,
248 so the parser knows the name (and possibly prototype) while it processes the
249 body. Thus C<fun foo($x) :($) { $x }> really turns into
250 C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
252 If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
253 put them after the parameter list with their usual syntax.
255 Syntactically, these new parameter lists live in the spot normally occupied
256 by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
257 specifying it as the first attribute (this is syntactically unambiguous
258 because normal attributes have to start with a letter while a prototype starts
261 As an example, the following declaration uses every feature available
262 (subroutine name, parameter list, prototype, attributes, and implicit
265 method foo($x, $y, @z) :($;$@) :lvalue :Banana(2 + 2) {
269 And here's what it turns into:
271 sub foo ($;$@); sub foo ($;$@) :lvalue :Banana(2 + 2) { my $self = shift; my ($x, $y, @z) = @_;
277 my $coderef = fun ($p, $q) :(;$$)
283 And the generated code:
285 my $coderef = sub (;$$) :lvalue :Gazebo((>:O)) { my ($p, $q) = @_;
289 =head2 Wrapping Function::Parameters
291 If you want to wrap L<Function::Parameters>, you just have to call its
292 C<import> method. It always applies to the file that is currently being parsed
293 and its effects are lexical (i.e. it works like L<warnings> or L<strict>):
295 package Some::Wrapper;
296 use Function::Parameters ();
298 Function::Parameters->import;
299 # or Function::Parameters->import(@other_import_args);
304 Lukas Mai, C<< <l.mai at web.de> >>
306 =head1 COPYRIGHT & LICENSE
308 Copyright 2010, 2011, 2012 Lukas Mai.
310 This program is free software; you can redistribute it and/or modify it
311 under the terms of either: the GNU General Public License as published
312 by the Free Software Foundation; or the Artistic License.
314 See http://dev.perl.org/licenses/ for more information.