Commit | Line | Data |
94caac6e |
1 | package Devel::Declare; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | use 5.008001; |
6 | |
98820f7a |
7 | our $VERSION = '0.005003'; |
0ba8c7aa |
8 | |
9 | use constant DECLARE_NAME => 1; |
10 | use constant DECLARE_PROTO => 2; |
53e3ab32 |
11 | use constant DECLARE_NONE => 4; |
15d0d014 |
12 | use constant DECLARE_PACKAGE => 8+1; # name implicit |
0ba8c7aa |
13 | |
86c3de80 |
14 | use vars qw(%declarators %declarator_handlers @ISA); |
94caac6e |
15 | use base qw(DynaLoader); |
323ae557 |
16 | use Scalar::Util 'set_prototype'; |
b15aa864 |
17 | use B::Hooks::OP::Check; |
94caac6e |
18 | |
19 | bootstrap Devel::Declare; |
20 | |
86c3de80 |
21 | @ISA = (); |
22 | |
94caac6e |
23 | sub import { |
0ba8c7aa |
24 | my ($class, %args) = @_; |
94caac6e |
25 | my $target = caller; |
0ba8c7aa |
26 | if (@_ == 1) { # "use Devel::Declare;" |
27 | no strict 'refs'; |
15d0d014 |
28 | foreach my $name (qw(NAME PROTO NONE PACKAGE)) { |
53e3ab32 |
29 | *{"${target}::DECLARE_${name}"} = *{"DECLARE_${name}"}; |
0ba8c7aa |
30 | } |
31 | } else { |
32 | $class->setup_for($target => \%args); |
33 | } |
94caac6e |
34 | } |
35 | |
36 | sub unimport { |
37 | my ($class) = @_; |
38 | my $target = caller; |
39 | $class->teardown_for($target); |
40 | } |
41 | |
42 | sub setup_for { |
43 | my ($class, $target, $args) = @_; |
44 | setup(); |
0ba8c7aa |
45 | foreach my $key (keys %$args) { |
46 | my $info = $args->{$key}; |
47 | my ($flags, $sub); |
48 | if (ref($info) eq 'ARRAY') { |
49 | ($flags, $sub) = @$info; |
50 | } elsif (ref($info) eq 'CODE') { |
51 | $flags = DECLARE_NAME; |
52 | $sub = $info; |
840ebcbb |
53 | } elsif (ref($info) eq 'HASH') { |
54 | $flags = 1; |
55 | $sub = $info; |
0ba8c7aa |
56 | } else { |
840ebcbb |
57 | die "Info for sub ${key} must be [ \$flags, \$sub ] or \$sub or handler hashref"; |
0ba8c7aa |
58 | } |
59 | $declarators{$target}{$key} = $flags; |
60 | $declarator_handlers{$target}{$key} = $sub; |
61 | } |
94caac6e |
62 | } |
63 | |
64 | sub teardown_for { |
65 | my ($class, $target) = @_; |
66 | delete $declarators{$target}; |
0ba8c7aa |
67 | delete $declarator_handlers{$target}; |
94caac6e |
68 | } |
69 | |
94caac6e |
70 | my $temp_name; |
0ba8c7aa |
71 | my $temp_save; |
94caac6e |
72 | |
73 | sub init_declare { |
0f070758 |
74 | my ($usepack, $use, $inpack, $name, $proto, $traits) = @_; |
53e3ab32 |
75 | my ($name_h, $XX_h, $extra_code) |
9026391e |
76 | = $declarator_handlers{$usepack}{$use}->( |
0f070758 |
77 | $usepack, $use, $inpack, $name, $proto, defined(wantarray), $traits |
53e3ab32 |
78 | ); |
15d0d014 |
79 | ($temp_name, $temp_save) = ([], []); |
0ba8c7aa |
80 | if ($name) { |
9026391e |
81 | $name = "${inpack}::${name}" unless $name =~ /::/; |
840ebcbb |
82 | shadow_sub($name, $name_h); |
0ba8c7aa |
83 | } |
84 | if ($XX_h) { |
840ebcbb |
85 | shadow_sub("${inpack}::X", $XX_h); |
0ba8c7aa |
86 | } |
53e3ab32 |
87 | if (defined wantarray) { |
88 | return $extra_code || '0;'; |
89 | } else { |
90 | return; |
91 | } |
94caac6e |
92 | } |
93 | |
840ebcbb |
94 | sub shadow_sub { |
95 | my ($name, $cr) = @_; |
96 | push(@$temp_name, $name); |
97 | no strict 'refs'; |
98 | my ($pack, $pname) = ($name =~ m/(.+)::([^:]+)/); |
99 | push(@$temp_save, $pack->can($pname)); |
840ebcbb |
100 | no warnings 'redefine'; |
101 | no warnings 'prototype'; |
102 | *{$name} = $cr; |
103 | set_in_declare(~~@{$temp_name||[]}); |
104 | } |
105 | |
94caac6e |
106 | sub done_declare { |
107 | no strict 'refs'; |
86c3de80 |
108 | my $name = shift(@{$temp_name||[]}); |
0ba8c7aa |
109 | die "done_declare called with no temp_name stack" unless defined($name); |
86c3de80 |
110 | my $saved = shift(@$temp_save); |
15d0d014 |
111 | $name =~ s/(.*):://; |
112 | my $temp_pack = $1; |
0ba8c7aa |
113 | delete ${"${temp_pack}::"}{$name}; |
114 | if ($saved) { |
115 | no warnings 'prototype'; |
116 | *{"${temp_pack}::${name}"} = $saved; |
117 | } |
840ebcbb |
118 | set_in_declare(~~@{$temp_name||[]}); |
94caac6e |
119 | } |
120 | |
323ae557 |
121 | sub build_sub_installer { |
122 | my ($class, $pack, $name, $proto) = @_; |
123 | return eval " |
124 | package ${pack}; |
125 | my \$body; |
126 | sub ${name} (${proto}) :lvalue {\n" |
003ac394 |
127 | .' if (wantarray) { |
c5912dc7 |
128 | goto &$body; |
003ac394 |
129 | } |
130 | my $ret = $body->(@_); |
86c3de80 |
131 | return $ret; |
323ae557 |
132 | }; |
133 | sub { ($body) = @_; };'; |
134 | } |
135 | |
136 | sub setup_declarators { |
137 | my ($class, $pack, $to_setup) = @_; |
86c3de80 |
138 | die "${class}->setup_declarators(\$pack, \\\%to_setup)" |
139 | unless defined($pack) && ref($to_setup) eq 'HASH'; |
140 | my %setup_for_args; |
323ae557 |
141 | foreach my $name (keys %$to_setup) { |
142 | my $info = $to_setup->{$name}; |
143 | my $flags = $info->{flags} || DECLARE_NAME; |
144 | my $run = $info->{run}; |
145 | my $compile = $info->{compile}; |
146 | my $proto = $info->{proto} || '&'; |
147 | my $sub_proto = $proto; |
148 | # make all args optional to enable lvalue for DECLARE_NONE |
149 | $sub_proto =~ s/;//; $sub_proto = ';'.$sub_proto; |
86c3de80 |
150 | #my $installer = $class->build_sub_installer($pack, $name, $proto); |
151 | my $installer = $class->build_sub_installer($pack, $name, '@'); |
86c3de80 |
152 | $installer->(sub :lvalue { |
003ac394 |
153 | #{ no warnings 'uninitialized'; warn 'INST: '.join(', ', @_)."\n"; } |
c5534496 |
154 | if (@_) { |
155 | if (ref $_[0] eq 'HASH') { |
156 | shift; |
003ac394 |
157 | if (wantarray) { |
158 | my @ret = $run->(undef, undef, @_); |
159 | return @ret; |
160 | } |
c5534496 |
161 | my $r = $run->(undef, undef, @_); |
162 | return $r; |
163 | } else { |
003ac394 |
164 | return @_[1..$#_]; |
c5534496 |
165 | } |
86c3de80 |
166 | } |
167 | return my $sv; |
168 | }); |
169 | $setup_for_args{$name} = [ |
170 | $flags, |
171 | sub { |
0f070758 |
172 | my ($usepack, $use, $inpack, $name, $proto, $shift_hashref, $traits) = @_; |
173 | my $extra_code = $compile->($name, $proto, $traits); |
003ac394 |
174 | my $main_handler = sub { shift if $shift_hashref; |
c5534496 |
175 | ("DONE", $run->($name, $proto, @_)); |
003ac394 |
176 | }; |
86c3de80 |
177 | my ($name_h, $XX); |
178 | if (defined $proto) { |
179 | $name_h = sub :lvalue { return my $sv; }; |
180 | $XX = $main_handler; |
c5534496 |
181 | } elsif (defined $name && length $name) { |
86c3de80 |
182 | $name_h = $main_handler; |
183 | } |
003ac394 |
184 | $extra_code ||= ''; |
185 | $extra_code = '}, sub {'.$extra_code; |
86c3de80 |
186 | return ($name_h, $XX, $extra_code); |
187 | } |
188 | ]; |
323ae557 |
189 | } |
86c3de80 |
190 | $class->setup_for($pack, \%setup_for_args); |
191 | } |
192 | |
193 | sub install_declarator { |
194 | my ($class, $target_pack, $target_name, $flags, $filter, $handler) = @_; |
195 | $class->setup_declarators($target_pack, { |
196 | $target_name => { |
197 | flags => $flags, |
198 | compile => $filter, |
199 | run => $handler, |
200 | } |
201 | }); |
323ae557 |
202 | } |
203 | |
04a8a223 |
204 | sub linestr_callback_rv2cv { |
205 | my ($name, $offset) = @_; |
206 | $offset += toke_move_past_token($offset); |
207 | my $pack = get_curstash_name(); |
208 | my $flags = $declarators{$pack}{$name}; |
209 | my ($found_name, $found_proto); |
04a8a223 |
210 | if ($flags & DECLARE_NAME) { |
211 | $offset += toke_skipspace($offset); |
212 | my $linestr = get_linestr(); |
213 | if (substr($linestr, $offset, 2) eq '::') { |
214 | substr($linestr, $offset, 2) = ''; |
215 | set_linestr($linestr); |
216 | } |
217 | if (my $len = toke_scan_word($offset, $flags & DECLARE_PACKAGE)) { |
218 | $found_name = substr($linestr, $offset, $len); |
219 | $offset += $len; |
04a8a223 |
220 | } |
221 | } |
222 | if ($flags & DECLARE_PROTO) { |
223 | $offset += toke_skipspace($offset); |
224 | my $linestr = get_linestr(); |
225 | if (substr($linestr, $offset, 1) eq '(') { |
226 | my $length = toke_scan_str($offset); |
227 | $found_proto = get_lex_stuff(); |
228 | clear_lex_stuff(); |
229 | my $replace = |
230 | ($found_name ? ' ' : '=') |
231 | .'X'.(' ' x length($found_proto)); |
232 | $linestr = get_linestr(); |
233 | substr($linestr, $offset, $length) = $replace; |
234 | set_linestr($linestr); |
235 | $offset += $length; |
04a8a223 |
236 | } |
237 | } |
238 | my @args = ($pack, $name, $pack, $found_name, $found_proto); |
04a8a223 |
239 | $offset += toke_skipspace($offset); |
240 | my $linestr = get_linestr(); |
241 | if (substr($linestr, $offset, 1) eq '{') { |
242 | my $ret = init_declare(@args); |
243 | $offset++; |
244 | if (defined $ret && length $ret) { |
245 | substr($linestr, $offset, 0) = $ret; |
246 | set_linestr($linestr); |
247 | } |
248 | } else { |
249 | init_declare(@args); |
250 | } |
251 | #warn "linestr now ${linestr}"; |
252 | } |
253 | |
569ac469 |
254 | sub linestr_callback_const { |
04a8a223 |
255 | my ($name, $offset) = @_; |
256 | my $pack = get_curstash_name(); |
257 | my $flags = $declarators{$pack}{$name}; |
258 | if ($flags & DECLARE_NAME) { |
259 | $offset += toke_move_past_token($offset); |
260 | $offset += toke_skipspace($offset); |
261 | if (toke_scan_word($offset, $flags & DECLARE_PACKAGE)) { |
262 | my $linestr = get_linestr(); |
263 | substr($linestr, $offset, 0) = '::'; |
264 | set_linestr($linestr); |
265 | } |
266 | } |
569ac469 |
267 | } |
268 | |
269 | sub linestr_callback { |
270 | my $type = shift; |
840ebcbb |
271 | my $name = $_[0]; |
272 | my $pack = get_curstash_name(); |
273 | my $handlers = $declarator_handlers{$pack}{$name}; |
274 | if (ref $handlers eq 'CODE') { |
275 | my $meth = "linestr_callback_${type}"; |
276 | __PACKAGE__->can($meth)->(@_); |
277 | } elsif (ref $handlers eq 'HASH') { |
278 | if ($handlers->{$type}) { |
279 | $handlers->{$type}->(@_); |
280 | } |
281 | } else { |
282 | die "PANIC: unknown thing in handlers for $pack $name: $handlers"; |
283 | } |
569ac469 |
284 | } |
285 | |
94caac6e |
286 | =head1 NAME |
287 | |
7e31b6e3 |
288 | Devel::Declare - Adding keywords to perl, in perl |
94caac6e |
289 | |
290 | =head1 SYNOPSIS |
291 | |
1795217c |
292 | use Method::Signatures; |
293 | # or ... |
294 | use MooseX::Declare; |
295 | # etc. |
296 | |
297 | # Use some new and exciting syntax like: |
298 | method hello (Str :$who, Int :$age where { $_ > 0 }) { |
299 | $self->say("Hello ${who}, I am ${age} years old!"); |
300 | } |
301 | |
302 | =head1 DESCRIPTION |
303 | |
304 | L<Devel::Declare> can install subroutines called declarators which locally take |
305 | over Perl's parser, allowing the creation of new syntax. |
306 | |
307 | This document describes how to create a simple declarator. |
308 | |
309 | =head1 USAGE |
310 | |
311 | We'll demonstrate the usage of C<Devel::Declare> with a motivating example: a new |
312 | C<method> keyword, which acts like the builtin C<sub>, but automatically unpacks |
313 | C<$self> and the other arguments. |
314 | |
315 | package My::Methods; |
316 | use Devel::Declare; |
317 | |
318 | =head2 Creating a declarator with C<setup_for> |
319 | |
320 | You will typically create |
321 | |
322 | sub import { |
323 | my $class = shift; |
324 | my $caller = caller; |
325 | |
326 | Devel::Declare->setup_for( |
327 | $caller, |
328 | { method => { const => \&parser } } |
329 | ); |
330 | no strict 'refs'; |
331 | *{$caller.'::method'} = sub (&) {}; |
332 | } |
333 | |
334 | Starting from the end of this import routine, you'll see that we're creating a |
335 | subroutine called C<method> in the caller's namespace. Yes, that's just a normal |
336 | subroutine, and it does nothing at all (yet!) Note the prototype C<(&)> which means |
337 | that the caller would call it like so: |
338 | |
339 | method { |
340 | my ($self, $arg1, $arg2) = @_; |
341 | ... |
342 | } |
343 | |
344 | However we want to be able to call it like this |
345 | |
346 | method foo ($arg1, $arg2) { |
347 | ... |
348 | } |
349 | |
350 | That's why we call C<setup_for> above, to register the declarator 'method' with a custom |
351 | parser, as per the next section. It acts on an optype, usually C<'const'> as above. |
352 | (Other valid values are C<'check'> and C<'rv2cv'>). |
353 | |
354 | For a simpler way to install new methods, see also L<Devel::Declare::MethodInstaller::Simple> |
355 | |
356 | =head2 Writing a parser subroutine |
357 | |
358 | This subroutine is called at I<compilation> time, and allows you to read the custom |
359 | syntaxes that we want (in a syntax that may or may not be valid core Perl 5) and |
360 | munge it so that the result will be parsed by the C<perl> compiler. |
361 | |
362 | For this example, we're defining some globals for convenience: |
363 | |
2ee34f20 |
364 | our ($Declarator, $Offset); |
1795217c |
365 | |
366 | Then we define a parser subroutine to handle our declarator. We'll look at this in |
367 | a few chunks. |
368 | |
369 | sub parser { |
370 | local ($Declarator, $Offset) = @_; |
371 | |
372 | C<Devel::Declare> provides some very low level utility methods to parse character |
373 | strings. We'll define some useful higher level routines below for convenience, |
374 | and we can use these to parse the various elements in our new syntax. |
375 | |
376 | Notice how our parser subroutine is invoked at compile time, |
377 | when the C<perl> parser is pointed just I<before> the declarator name. |
378 | |
379 | skip_declarator; # step past 'method' |
380 | my $name = strip_name; # strip out the name 'foo', if present |
381 | my $proto = strip_proto; # strip out the prototype '($arg1, $arg2)', if present |
382 | |
383 | Now we can prepare some code to 'inject' into the new subroutine. For example we |
384 | might want the method as above to have C<my ($self, $arg1, $arg2) = @_> injected at |
385 | the beginning of it. We also do some clever stuff with scopes that we'll look |
386 | at shortly. |
387 | |
388 | my $inject = make_proto_unwrap($proto); |
389 | if (defined $name) { |
390 | $inject = scope_injector_call().$inject; |
391 | } |
392 | inject_if_block($inject); |
393 | |
394 | We've now managed to change C<method ($arg1, $arg2) { ... }> into C<method { |
395 | injected_code; ... }>. This will compile... but we've lost the name of the |
396 | method! |
397 | |
398 | In a cute (or horrifying, depending on your perspective) trick, we temporarily |
399 | change the definition of the subroutine C<method> itself, to specialise it with |
400 | the C<$name> we stripped, so that it assigns the code block to that name. |
401 | |
402 | Even though the I<next> time C<method> is compiled, it will be |
403 | redefined again, C<perl> caches these definitions in its parse |
404 | tree, so we'll always get the right one! |
405 | |
406 | Note that we also handle the case where there was no name, allowing |
407 | an anonymous method analogous to an anonymous subroutine. |
408 | |
409 | if (defined $name) { |
410 | $name = join('::', Devel::Declare::get_curstash_name(), $name) |
411 | unless ($name =~ /::/); |
412 | shadow(sub (&) { no strict 'refs'; *{$name} = shift; }); |
413 | } else { |
414 | shadow(sub (&) { shift }); |
415 | } |
416 | } |
417 | |
418 | |
419 | =head2 Parser utilities in detail |
420 | |
421 | For simplicity, we're using global variables like C<$Offset> in these examples. |
422 | You may prefer to look at L<Devel::Declare::Context::Simple>, which |
423 | encapsulates the context much more cleanly. |
424 | |
425 | =head3 C<skip_declarator> |
426 | |
427 | This simple parser just moves across a 'token'. The common case is |
428 | to skip the declarator, i.e. to move to the end of the string |
429 | 'method' and before the prototype and code block. |
430 | |
2ee34f20 |
431 | sub skip_declarator { |
432 | $Offset += Devel::Declare::toke_move_past_token($Offset); |
433 | } |
1795217c |
434 | |
435 | =head4 C<toke_move_past_token> |
436 | |
437 | This builtin parser simply moves past a 'token' (matching C</[a-zA-Z_]\w*/>) |
438 | It takes an offset into the source document, and skips past the token. |
439 | It returns the number of characters skipped. |
440 | |
441 | =head3 C<strip_name> |
442 | |
443 | This parser skips any whitespace, then scans the next word (again matching a |
444 | 'token'). We can then analyse the current line, and manipulate it (using pure |
445 | Perl). In this case we take the name of the method out, and return it. |
446 | |
2ee34f20 |
447 | sub strip_name { |
448 | skipspace; |
449 | if (my $len = Devel::Declare::toke_scan_word($Offset, 1)) { |
450 | my $linestr = Devel::Declare::get_linestr(); |
451 | my $name = substr($linestr, $Offset, $len); |
452 | substr($linestr, $Offset, $len) = ''; |
453 | Devel::Declare::set_linestr($linestr); |
454 | return $name; |
455 | } |
456 | return; |
457 | } |
1795217c |
458 | |
459 | =head4 C<toke_scan_word> |
460 | |
461 | This builtin parser, given an offset into the source document, |
462 | matches a 'token' as above but does not skip. It returns the |
463 | length of the token matched, if any. |
464 | |
465 | =head4 C<get_linestr> |
466 | |
467 | This builtin returns the full text of the current line of the source document. |
468 | |
469 | =head4 C<set_linestr> |
470 | |
471 | This builtin sets the full text of the current line of the source document. |
472 | |
473 | =head3 C<skipspace> |
474 | |
475 | This parser skips whitsepace. |
476 | |
477 | sub skipspace { |
478 | $Offset += Devel::Declare::toke_skipspace($Offset); |
479 | } |
480 | |
481 | =head4 C<toke_skipspace> |
482 | |
483 | This builtin parser, given an offset into the source document, |
484 | skips over any whitespace, and returns the number of characters |
485 | skipped. |
486 | |
487 | =head3 C<strip_proto> |
488 | |
489 | This is a more complex parser that checks if it's found something that |
490 | starts with C<'('> and returns everything till the matching C<')'>. |
491 | |
2ee34f20 |
492 | sub strip_proto { |
493 | skipspace; |
1795217c |
494 | |
2ee34f20 |
495 | my $linestr = Devel::Declare::get_linestr(); |
496 | if (substr($linestr, $Offset, 1) eq '(') { |
497 | my $length = Devel::Declare::toke_scan_str($Offset); |
498 | my $proto = Devel::Declare::get_lex_stuff(); |
499 | Devel::Declare::clear_lex_stuff(); |
500 | $linestr = Devel::Declare::get_linestr(); |
501 | substr($linestr, $Offset, $length) = ''; |
502 | Devel::Declare::set_linestr($linestr); |
503 | return $proto; |
504 | } |
505 | return; |
506 | } |
1795217c |
507 | |
508 | =head4 C<toke_scan_str> |
509 | |
510 | This builtin parser uses Perl's own parsing routines to match a "stringlike" |
511 | expression. Handily, this includes bracketed expressions (just think about |
512 | things like C<q(this is a quote)>). |
513 | |
514 | Also it Does The Right Thing with nested delimiters (like C<q(this (is (a) quote))>). |
515 | |
516 | It returns the length of the expression matched. Use C<get_lex_stuff> to |
517 | get the actual matched text. |
518 | |
519 | =head4 C<get_lex_stuff> |
520 | |
521 | This builtin returns what was matched by C<toke_scan_str>. To avoid segfaults, |
522 | you should call C<clear_lex_stuff> immediately afterwards. |
523 | |
524 | =head2 Munging the subroutine |
525 | |
526 | Let's look at what we need to do in detail. |
527 | |
528 | =head3 C<make_proto_unwrap> |
529 | |
530 | We may have defined our method in different ways, which will result |
531 | in a different value for our prototype, as parsed above. For example: |
532 | |
533 | method foo { # undefined |
534 | method foo () { # '' |
535 | method foo ($arg1) { # '$arg1' |
536 | |
537 | We deal with them as follows, and return the appropriate C<my ($self, ...) = @_;> |
538 | string. |
539 | |
2ee34f20 |
540 | sub make_proto_unwrap { |
541 | my ($proto) = @_; |
542 | my $inject = 'my ($self'; |
543 | if (defined $proto) { |
544 | $inject .= ", $proto" if length($proto); |
545 | $inject .= ') = @_; '; |
546 | } else { |
547 | $inject .= ') = shift;'; |
548 | } |
549 | return $inject; |
550 | } |
1795217c |
551 | |
552 | =head3 C<inject_if_block> |
553 | |
554 | Now we need to inject it after the opening C<'{'> of the method body. |
555 | We can do this with the building blocks we defined above like C<skipspace> |
556 | and C<get_linestr>. |
557 | |
2ee34f20 |
558 | sub inject_if_block { |
559 | my $inject = shift; |
560 | skipspace; |
561 | my $linestr = Devel::Declare::get_linestr; |
562 | if (substr($linestr, $Offset, 1) eq '{') { |
563 | substr($linestr, $Offset+1, 0) = $inject; |
564 | Devel::Declare::set_linestr($linestr); |
565 | } |
566 | } |
94caac6e |
567 | |
1795217c |
568 | =head3 C<scope_injector_call> |
569 | |
570 | We want to be able to handle both named and anonymous methods. i.e. |
571 | |
572 | method foo () { ... } |
573 | my $meth = method () { ... }; |
574 | |
575 | These will then get rewritten as |
576 | |
577 | method { ... } |
578 | my $meth = method { ... }; |
579 | |
580 | where 'method' is a subroutine that takes a code block. Spot the problem? |
581 | The first one doesn't have a semicolon at the end of it! Unlike 'sub' which |
582 | is a builtin, this is just a normal statement, so we need to terminate it. |
6c1cecd4 |
583 | Luckily, using C<B::Hooks::EndOfScope>, we can do this! |
1795217c |
584 | |
6c1cecd4 |
585 | use B::Hooks::EndOfScope; |
1795217c |
586 | |
587 | We'll add this to what gets 'injected' at the beginning of the method source. |
588 | |
589 | sub scope_injector_call { |
590 | return ' BEGIN { MethodHandlers::inject_scope }; '; |
2ee34f20 |
591 | } |
1795217c |
592 | |
5bcdf810 |
593 | So at the beginning of every method, we are passing a callback that will get invoked |
1795217c |
594 | at the I<end> of the method's compilation... i.e. exactly then the closing C<'}'> |
595 | is compiled. |
596 | |
597 | sub inject_scope { |
6c1cecd4 |
598 | on_scope_end { |
1795217c |
599 | my $linestr = Devel::Declare::get_linestr; |
600 | my $offset = Devel::Declare::get_linestr_offset; |
601 | substr($linestr, $offset, 0) = ';'; |
602 | Devel::Declare::set_linestr($linestr); |
6c1cecd4 |
603 | }; |
2ee34f20 |
604 | } |
94caac6e |
605 | |
1795217c |
606 | =head2 Shadowing each method. |
607 | |
608 | =head3 C<shadow> |
94caac6e |
609 | |
1795217c |
610 | We override the current definition of 'method' using C<shadow>. |
94caac6e |
611 | |
1795217c |
612 | sub shadow { |
613 | my $pack = Devel::Declare::get_curstash_name; |
614 | Devel::Declare::shadow_sub("${pack}::${Declarator}", $_[0]); |
2ee34f20 |
615 | } |
94caac6e |
616 | |
1795217c |
617 | For a named method we invoked like this: |
618 | |
619 | shadow(sub (&) { no strict 'refs'; *{$name} = shift; }); |
620 | |
621 | So in the case of a C<method foo { ... }>, this call would redefine C<method> |
622 | to be a subroutine that exports 'sub foo' as the (munged) contents of C<{...}>. |
623 | |
624 | The case of an anonymous method is also cute: |
625 | |
626 | shadow(sub (&) { shift }); |
627 | |
628 | This means that |
629 | |
630 | my $meth = method () { ... }; |
631 | |
632 | is rewritten with C<method> taking the codeblock, and returning it as is to become |
633 | the value of C<$meth>. |
634 | |
635 | =head4 C<get_curstash_name> |
636 | |
637 | This returns the package name I<currently being compiled>. |
638 | |
639 | =head4 C<shadow_sub> |
640 | |
641 | Handles the details of redefining the subroutine. |
642 | |
643 | =head1 SEE ALSO |
644 | |
645 | One of the best ways to learn C<Devel::Declare> is still to look at |
646 | modules that use it: |
647 | |
648 | L<http://cpants.perl.org/dist/used_by/Devel-Declare>. |
94caac6e |
649 | |
dcf29eb6 |
650 | =head1 AUTHORS |
94caac6e |
651 | |
502ba90e |
652 | Matt S Trout - E<lt>mst@shadowcat.co.ukE<gt> - original author |
94caac6e |
653 | |
02f5a508 |
654 | Company: http://www.shadowcat.co.uk/ |
94caac6e |
655 | Blog: http://chainsawblues.vox.com/ |
656 | |
1795217c |
657 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> - maintainer |
658 | |
0df492b9 |
659 | osfameron E<lt>osfameron@cpan.orgE<gt> - first draft of documentation |
dcf29eb6 |
660 | |
107322d1 |
661 | =head1 COPYRIGHT AND LICENSE |
662 | |
09addf7a |
663 | This library is free software under the same terms as perl itself |
664 | |
107322d1 |
665 | Copyright (c) 2007, 2008, 2009 Matt S Trout |
666 | |
667 | Copyright (c) 2008, 2009 Florian Ragwitz |
94caac6e |
668 | |
09addf7a |
669 | stolen_chunk_of_toke.c based on toke.c from the perl core, which is |
670 | |
671 | Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
672 | 2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others |
94caac6e |
673 | |
674 | =cut |
675 | |
676 | 1; |