Commit | Line | Data |
94caac6e |
1 | package Devel::Declare; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | use 5.008001; |
6 | |
5591a785 |
7 | our $VERSION = '0.005011'; |
0ba8c7aa |
8 | |
9 | use constant DECLARE_NAME => 1; |
10 | use constant DECLARE_PROTO => 2; |
53e3ab32 |
11 | use constant DECLARE_NONE => 4; |
15d0d014 |
12 | use constant DECLARE_PACKAGE => 8+1; # name implicit |
0ba8c7aa |
13 | |
86c3de80 |
14 | use vars qw(%declarators %declarator_handlers @ISA); |
94caac6e |
15 | use base qw(DynaLoader); |
323ae557 |
16 | use Scalar::Util 'set_prototype'; |
b15aa864 |
17 | use B::Hooks::OP::Check; |
94caac6e |
18 | |
19 | bootstrap Devel::Declare; |
20 | |
86c3de80 |
21 | @ISA = (); |
22 | |
94caac6e |
23 | sub import { |
0ba8c7aa |
24 | my ($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)); |
a84a41f6 |
100 | delete ${ "${pack}::" }{$pname}; |
840ebcbb |
101 | no warnings 'redefine'; |
102 | no warnings 'prototype'; |
103 | *{$name} = $cr; |
104 | set_in_declare(~~@{$temp_name||[]}); |
105 | } |
106 | |
94caac6e |
107 | sub done_declare { |
108 | no strict 'refs'; |
86c3de80 |
109 | my $name = shift(@{$temp_name||[]}); |
0ba8c7aa |
110 | die "done_declare called with no temp_name stack" unless defined($name); |
86c3de80 |
111 | my $saved = shift(@$temp_save); |
15d0d014 |
112 | $name =~ s/(.*):://; |
113 | my $temp_pack = $1; |
0ba8c7aa |
114 | delete ${"${temp_pack}::"}{$name}; |
115 | if ($saved) { |
116 | no warnings 'prototype'; |
117 | *{"${temp_pack}::${name}"} = $saved; |
118 | } |
840ebcbb |
119 | set_in_declare(~~@{$temp_name||[]}); |
94caac6e |
120 | } |
121 | |
323ae557 |
122 | sub build_sub_installer { |
123 | my ($class, $pack, $name, $proto) = @_; |
124 | return eval " |
125 | package ${pack}; |
126 | my \$body; |
127 | sub ${name} (${proto}) :lvalue {\n" |
003ac394 |
128 | .' if (wantarray) { |
c5912dc7 |
129 | goto &$body; |
003ac394 |
130 | } |
131 | my $ret = $body->(@_); |
86c3de80 |
132 | return $ret; |
323ae557 |
133 | }; |
134 | sub { ($body) = @_; };'; |
135 | } |
136 | |
137 | sub setup_declarators { |
138 | my ($class, $pack, $to_setup) = @_; |
86c3de80 |
139 | die "${class}->setup_declarators(\$pack, \\\%to_setup)" |
140 | unless defined($pack) && ref($to_setup) eq 'HASH'; |
141 | my %setup_for_args; |
323ae557 |
142 | foreach my $name (keys %$to_setup) { |
143 | my $info = $to_setup->{$name}; |
144 | my $flags = $info->{flags} || DECLARE_NAME; |
145 | my $run = $info->{run}; |
146 | my $compile = $info->{compile}; |
147 | my $proto = $info->{proto} || '&'; |
148 | my $sub_proto = $proto; |
149 | # make all args optional to enable lvalue for DECLARE_NONE |
150 | $sub_proto =~ s/;//; $sub_proto = ';'.$sub_proto; |
86c3de80 |
151 | #my $installer = $class->build_sub_installer($pack, $name, $proto); |
152 | my $installer = $class->build_sub_installer($pack, $name, '@'); |
86c3de80 |
153 | $installer->(sub :lvalue { |
003ac394 |
154 | #{ no warnings 'uninitialized'; warn 'INST: '.join(', ', @_)."\n"; } |
c5534496 |
155 | if (@_) { |
156 | if (ref $_[0] eq 'HASH') { |
157 | shift; |
003ac394 |
158 | if (wantarray) { |
159 | my @ret = $run->(undef, undef, @_); |
160 | return @ret; |
161 | } |
c5534496 |
162 | my $r = $run->(undef, undef, @_); |
163 | return $r; |
164 | } else { |
003ac394 |
165 | return @_[1..$#_]; |
c5534496 |
166 | } |
86c3de80 |
167 | } |
168 | return my $sv; |
169 | }); |
170 | $setup_for_args{$name} = [ |
171 | $flags, |
172 | sub { |
0f070758 |
173 | my ($usepack, $use, $inpack, $name, $proto, $shift_hashref, $traits) = @_; |
174 | my $extra_code = $compile->($name, $proto, $traits); |
003ac394 |
175 | my $main_handler = sub { shift if $shift_hashref; |
c5534496 |
176 | ("DONE", $run->($name, $proto, @_)); |
003ac394 |
177 | }; |
86c3de80 |
178 | my ($name_h, $XX); |
179 | if (defined $proto) { |
180 | $name_h = sub :lvalue { return my $sv; }; |
181 | $XX = $main_handler; |
c5534496 |
182 | } elsif (defined $name && length $name) { |
86c3de80 |
183 | $name_h = $main_handler; |
184 | } |
003ac394 |
185 | $extra_code ||= ''; |
186 | $extra_code = '}, sub {'.$extra_code; |
86c3de80 |
187 | return ($name_h, $XX, $extra_code); |
188 | } |
189 | ]; |
323ae557 |
190 | } |
86c3de80 |
191 | $class->setup_for($pack, \%setup_for_args); |
192 | } |
193 | |
194 | sub install_declarator { |
195 | my ($class, $target_pack, $target_name, $flags, $filter, $handler) = @_; |
196 | $class->setup_declarators($target_pack, { |
197 | $target_name => { |
198 | flags => $flags, |
199 | compile => $filter, |
200 | run => $handler, |
201 | } |
202 | }); |
323ae557 |
203 | } |
204 | |
04a8a223 |
205 | sub linestr_callback_rv2cv { |
206 | my ($name, $offset) = @_; |
207 | $offset += toke_move_past_token($offset); |
208 | my $pack = get_curstash_name(); |
209 | my $flags = $declarators{$pack}{$name}; |
210 | my ($found_name, $found_proto); |
04a8a223 |
211 | if ($flags & DECLARE_NAME) { |
212 | $offset += toke_skipspace($offset); |
213 | my $linestr = get_linestr(); |
214 | if (substr($linestr, $offset, 2) eq '::') { |
215 | substr($linestr, $offset, 2) = ''; |
216 | set_linestr($linestr); |
217 | } |
218 | if (my $len = toke_scan_word($offset, $flags & DECLARE_PACKAGE)) { |
219 | $found_name = substr($linestr, $offset, $len); |
220 | $offset += $len; |
04a8a223 |
221 | } |
222 | } |
223 | if ($flags & DECLARE_PROTO) { |
224 | $offset += toke_skipspace($offset); |
225 | my $linestr = get_linestr(); |
226 | if (substr($linestr, $offset, 1) eq '(') { |
227 | my $length = toke_scan_str($offset); |
228 | $found_proto = get_lex_stuff(); |
229 | clear_lex_stuff(); |
230 | my $replace = |
231 | ($found_name ? ' ' : '=') |
232 | .'X'.(' ' x length($found_proto)); |
233 | $linestr = get_linestr(); |
234 | substr($linestr, $offset, $length) = $replace; |
235 | set_linestr($linestr); |
236 | $offset += $length; |
04a8a223 |
237 | } |
238 | } |
239 | my @args = ($pack, $name, $pack, $found_name, $found_proto); |
04a8a223 |
240 | $offset += toke_skipspace($offset); |
241 | my $linestr = get_linestr(); |
242 | if (substr($linestr, $offset, 1) eq '{') { |
243 | my $ret = init_declare(@args); |
244 | $offset++; |
245 | if (defined $ret && length $ret) { |
246 | substr($linestr, $offset, 0) = $ret; |
247 | set_linestr($linestr); |
248 | } |
249 | } else { |
250 | init_declare(@args); |
251 | } |
252 | #warn "linestr now ${linestr}"; |
253 | } |
254 | |
569ac469 |
255 | sub linestr_callback_const { |
04a8a223 |
256 | my ($name, $offset) = @_; |
257 | my $pack = get_curstash_name(); |
258 | my $flags = $declarators{$pack}{$name}; |
259 | if ($flags & DECLARE_NAME) { |
260 | $offset += toke_move_past_token($offset); |
261 | $offset += toke_skipspace($offset); |
262 | if (toke_scan_word($offset, $flags & DECLARE_PACKAGE)) { |
263 | my $linestr = get_linestr(); |
264 | substr($linestr, $offset, 0) = '::'; |
265 | set_linestr($linestr); |
266 | } |
267 | } |
569ac469 |
268 | } |
269 | |
270 | sub linestr_callback { |
271 | my $type = shift; |
840ebcbb |
272 | my $name = $_[0]; |
273 | my $pack = get_curstash_name(); |
274 | my $handlers = $declarator_handlers{$pack}{$name}; |
275 | if (ref $handlers eq 'CODE') { |
276 | my $meth = "linestr_callback_${type}"; |
277 | __PACKAGE__->can($meth)->(@_); |
278 | } elsif (ref $handlers eq 'HASH') { |
279 | if ($handlers->{$type}) { |
280 | $handlers->{$type}->(@_); |
281 | } |
282 | } else { |
283 | die "PANIC: unknown thing in handlers for $pack $name: $handlers"; |
284 | } |
569ac469 |
285 | } |
286 | |
94caac6e |
287 | =head1 NAME |
288 | |
7e31b6e3 |
289 | Devel::Declare - Adding keywords to perl, in perl |
94caac6e |
290 | |
291 | =head1 SYNOPSIS |
292 | |
1795217c |
293 | use Method::Signatures; |
294 | # or ... |
295 | use MooseX::Declare; |
296 | # etc. |
297 | |
298 | # Use some new and exciting syntax like: |
299 | method hello (Str :$who, Int :$age where { $_ > 0 }) { |
300 | $self->say("Hello ${who}, I am ${age} years old!"); |
301 | } |
302 | |
303 | =head1 DESCRIPTION |
304 | |
305 | L<Devel::Declare> can install subroutines called declarators which locally take |
306 | over Perl's parser, allowing the creation of new syntax. |
307 | |
308 | This document describes how to create a simple declarator. |
309 | |
310 | =head1 USAGE |
311 | |
312 | We'll demonstrate the usage of C<Devel::Declare> with a motivating example: a new |
313 | C<method> keyword, which acts like the builtin C<sub>, but automatically unpacks |
314 | C<$self> and the other arguments. |
315 | |
316 | package My::Methods; |
317 | use Devel::Declare; |
318 | |
319 | =head2 Creating a declarator with C<setup_for> |
320 | |
321 | You will typically create |
322 | |
323 | sub import { |
324 | my $class = shift; |
325 | my $caller = caller; |
326 | |
327 | Devel::Declare->setup_for( |
328 | $caller, |
329 | { method => { const => \&parser } } |
330 | ); |
331 | no strict 'refs'; |
332 | *{$caller.'::method'} = sub (&) {}; |
333 | } |
334 | |
335 | Starting from the end of this import routine, you'll see that we're creating a |
336 | subroutine called C<method> in the caller's namespace. Yes, that's just a normal |
337 | subroutine, and it does nothing at all (yet!) Note the prototype C<(&)> which means |
338 | that the caller would call it like so: |
339 | |
340 | method { |
341 | my ($self, $arg1, $arg2) = @_; |
342 | ... |
343 | } |
344 | |
345 | However we want to be able to call it like this |
346 | |
347 | method foo ($arg1, $arg2) { |
348 | ... |
349 | } |
350 | |
351 | That's why we call C<setup_for> above, to register the declarator 'method' with a custom |
352 | parser, as per the next section. It acts on an optype, usually C<'const'> as above. |
353 | (Other valid values are C<'check'> and C<'rv2cv'>). |
354 | |
355 | For a simpler way to install new methods, see also L<Devel::Declare::MethodInstaller::Simple> |
356 | |
357 | =head2 Writing a parser subroutine |
358 | |
359 | This subroutine is called at I<compilation> time, and allows you to read the custom |
360 | syntaxes that we want (in a syntax that may or may not be valid core Perl 5) and |
361 | munge it so that the result will be parsed by the C<perl> compiler. |
362 | |
363 | For this example, we're defining some globals for convenience: |
364 | |
2ee34f20 |
365 | our ($Declarator, $Offset); |
1795217c |
366 | |
367 | Then we define a parser subroutine to handle our declarator. We'll look at this in |
368 | a few chunks. |
369 | |
370 | sub parser { |
371 | local ($Declarator, $Offset) = @_; |
372 | |
373 | C<Devel::Declare> provides some very low level utility methods to parse character |
374 | strings. We'll define some useful higher level routines below for convenience, |
375 | and we can use these to parse the various elements in our new syntax. |
376 | |
377 | Notice how our parser subroutine is invoked at compile time, |
378 | when the C<perl> parser is pointed just I<before> the declarator name. |
379 | |
380 | skip_declarator; # step past 'method' |
381 | my $name = strip_name; # strip out the name 'foo', if present |
382 | my $proto = strip_proto; # strip out the prototype '($arg1, $arg2)', if present |
383 | |
384 | Now we can prepare some code to 'inject' into the new subroutine. For example we |
385 | might want the method as above to have C<my ($self, $arg1, $arg2) = @_> injected at |
386 | the beginning of it. We also do some clever stuff with scopes that we'll look |
387 | at shortly. |
388 | |
389 | my $inject = make_proto_unwrap($proto); |
390 | if (defined $name) { |
391 | $inject = scope_injector_call().$inject; |
392 | } |
393 | inject_if_block($inject); |
394 | |
395 | We've now managed to change C<method ($arg1, $arg2) { ... }> into C<method { |
396 | injected_code; ... }>. This will compile... but we've lost the name of the |
397 | method! |
398 | |
399 | In a cute (or horrifying, depending on your perspective) trick, we temporarily |
400 | change the definition of the subroutine C<method> itself, to specialise it with |
401 | the C<$name> we stripped, so that it assigns the code block to that name. |
402 | |
403 | Even though the I<next> time C<method> is compiled, it will be |
404 | redefined again, C<perl> caches these definitions in its parse |
405 | tree, so we'll always get the right one! |
406 | |
407 | Note that we also handle the case where there was no name, allowing |
408 | an anonymous method analogous to an anonymous subroutine. |
409 | |
410 | if (defined $name) { |
411 | $name = join('::', Devel::Declare::get_curstash_name(), $name) |
412 | unless ($name =~ /::/); |
413 | shadow(sub (&) { no strict 'refs'; *{$name} = shift; }); |
414 | } else { |
415 | shadow(sub (&) { shift }); |
416 | } |
417 | } |
418 | |
419 | |
420 | =head2 Parser utilities in detail |
421 | |
422 | For simplicity, we're using global variables like C<$Offset> in these examples. |
423 | You may prefer to look at L<Devel::Declare::Context::Simple>, which |
424 | encapsulates the context much more cleanly. |
425 | |
426 | =head3 C<skip_declarator> |
427 | |
428 | This simple parser just moves across a 'token'. The common case is |
429 | to skip the declarator, i.e. to move to the end of the string |
430 | 'method' and before the prototype and code block. |
431 | |
2ee34f20 |
432 | sub skip_declarator { |
433 | $Offset += Devel::Declare::toke_move_past_token($Offset); |
434 | } |
1795217c |
435 | |
436 | =head4 C<toke_move_past_token> |
437 | |
438 | This builtin parser simply moves past a 'token' (matching C</[a-zA-Z_]\w*/>) |
439 | It takes an offset into the source document, and skips past the token. |
440 | It returns the number of characters skipped. |
441 | |
442 | =head3 C<strip_name> |
443 | |
444 | This parser skips any whitespace, then scans the next word (again matching a |
445 | 'token'). We can then analyse the current line, and manipulate it (using pure |
446 | Perl). In this case we take the name of the method out, and return it. |
447 | |
2ee34f20 |
448 | sub strip_name { |
449 | skipspace; |
450 | if (my $len = Devel::Declare::toke_scan_word($Offset, 1)) { |
451 | my $linestr = Devel::Declare::get_linestr(); |
452 | my $name = substr($linestr, $Offset, $len); |
453 | substr($linestr, $Offset, $len) = ''; |
454 | Devel::Declare::set_linestr($linestr); |
455 | return $name; |
456 | } |
457 | return; |
458 | } |
1795217c |
459 | |
460 | =head4 C<toke_scan_word> |
461 | |
462 | This builtin parser, given an offset into the source document, |
463 | matches a 'token' as above but does not skip. It returns the |
464 | length of the token matched, if any. |
465 | |
466 | =head4 C<get_linestr> |
467 | |
468 | This builtin returns the full text of the current line of the source document. |
469 | |
470 | =head4 C<set_linestr> |
471 | |
472 | This builtin sets the full text of the current line of the source document. |
473 | |
474 | =head3 C<skipspace> |
475 | |
476 | This parser skips whitsepace. |
477 | |
478 | sub skipspace { |
479 | $Offset += Devel::Declare::toke_skipspace($Offset); |
480 | } |
481 | |
482 | =head4 C<toke_skipspace> |
483 | |
484 | This builtin parser, given an offset into the source document, |
485 | skips over any whitespace, and returns the number of characters |
486 | skipped. |
487 | |
488 | =head3 C<strip_proto> |
489 | |
490 | This is a more complex parser that checks if it's found something that |
491 | starts with C<'('> and returns everything till the matching C<')'>. |
492 | |
2ee34f20 |
493 | sub strip_proto { |
494 | skipspace; |
1795217c |
495 | |
2ee34f20 |
496 | my $linestr = Devel::Declare::get_linestr(); |
497 | if (substr($linestr, $Offset, 1) eq '(') { |
498 | my $length = Devel::Declare::toke_scan_str($Offset); |
499 | my $proto = Devel::Declare::get_lex_stuff(); |
500 | Devel::Declare::clear_lex_stuff(); |
501 | $linestr = Devel::Declare::get_linestr(); |
502 | substr($linestr, $Offset, $length) = ''; |
503 | Devel::Declare::set_linestr($linestr); |
504 | return $proto; |
505 | } |
506 | return; |
507 | } |
1795217c |
508 | |
509 | =head4 C<toke_scan_str> |
510 | |
511 | This builtin parser uses Perl's own parsing routines to match a "stringlike" |
512 | expression. Handily, this includes bracketed expressions (just think about |
513 | things like C<q(this is a quote)>). |
514 | |
515 | Also it Does The Right Thing with nested delimiters (like C<q(this (is (a) quote))>). |
516 | |
517 | It returns the length of the expression matched. Use C<get_lex_stuff> to |
518 | get the actual matched text. |
519 | |
520 | =head4 C<get_lex_stuff> |
521 | |
522 | This builtin returns what was matched by C<toke_scan_str>. To avoid segfaults, |
523 | you should call C<clear_lex_stuff> immediately afterwards. |
524 | |
525 | =head2 Munging the subroutine |
526 | |
527 | Let's look at what we need to do in detail. |
528 | |
529 | =head3 C<make_proto_unwrap> |
530 | |
531 | We may have defined our method in different ways, which will result |
532 | in a different value for our prototype, as parsed above. For example: |
533 | |
534 | method foo { # undefined |
535 | method foo () { # '' |
536 | method foo ($arg1) { # '$arg1' |
537 | |
538 | We deal with them as follows, and return the appropriate C<my ($self, ...) = @_;> |
539 | string. |
540 | |
2ee34f20 |
541 | sub make_proto_unwrap { |
542 | my ($proto) = @_; |
543 | my $inject = 'my ($self'; |
544 | if (defined $proto) { |
545 | $inject .= ", $proto" if length($proto); |
546 | $inject .= ') = @_; '; |
547 | } else { |
548 | $inject .= ') = shift;'; |
549 | } |
550 | return $inject; |
551 | } |
1795217c |
552 | |
553 | =head3 C<inject_if_block> |
554 | |
555 | Now we need to inject it after the opening C<'{'> of the method body. |
556 | We can do this with the building blocks we defined above like C<skipspace> |
557 | and C<get_linestr>. |
558 | |
2ee34f20 |
559 | sub inject_if_block { |
560 | my $inject = shift; |
561 | skipspace; |
562 | my $linestr = Devel::Declare::get_linestr; |
563 | if (substr($linestr, $Offset, 1) eq '{') { |
564 | substr($linestr, $Offset+1, 0) = $inject; |
565 | Devel::Declare::set_linestr($linestr); |
566 | } |
567 | } |
94caac6e |
568 | |
1795217c |
569 | =head3 C<scope_injector_call> |
570 | |
571 | We want to be able to handle both named and anonymous methods. i.e. |
572 | |
573 | method foo () { ... } |
574 | my $meth = method () { ... }; |
575 | |
576 | These will then get rewritten as |
577 | |
578 | method { ... } |
579 | my $meth = method { ... }; |
580 | |
581 | where 'method' is a subroutine that takes a code block. Spot the problem? |
582 | The first one doesn't have a semicolon at the end of it! Unlike 'sub' which |
583 | is a builtin, this is just a normal statement, so we need to terminate it. |
6c1cecd4 |
584 | Luckily, using C<B::Hooks::EndOfScope>, we can do this! |
1795217c |
585 | |
6c1cecd4 |
586 | use B::Hooks::EndOfScope; |
1795217c |
587 | |
588 | We'll add this to what gets 'injected' at the beginning of the method source. |
589 | |
590 | sub scope_injector_call { |
591 | return ' BEGIN { MethodHandlers::inject_scope }; '; |
2ee34f20 |
592 | } |
1795217c |
593 | |
5bcdf810 |
594 | So at the beginning of every method, we are passing a callback that will get invoked |
1795217c |
595 | at the I<end> of the method's compilation... i.e. exactly then the closing C<'}'> |
596 | is compiled. |
597 | |
598 | sub inject_scope { |
6c1cecd4 |
599 | on_scope_end { |
1795217c |
600 | my $linestr = Devel::Declare::get_linestr; |
601 | my $offset = Devel::Declare::get_linestr_offset; |
602 | substr($linestr, $offset, 0) = ';'; |
603 | Devel::Declare::set_linestr($linestr); |
6c1cecd4 |
604 | }; |
2ee34f20 |
605 | } |
94caac6e |
606 | |
1795217c |
607 | =head2 Shadowing each method. |
608 | |
609 | =head3 C<shadow> |
94caac6e |
610 | |
1795217c |
611 | We override the current definition of 'method' using C<shadow>. |
94caac6e |
612 | |
1795217c |
613 | sub shadow { |
614 | my $pack = Devel::Declare::get_curstash_name; |
615 | Devel::Declare::shadow_sub("${pack}::${Declarator}", $_[0]); |
2ee34f20 |
616 | } |
94caac6e |
617 | |
1795217c |
618 | For a named method we invoked like this: |
619 | |
620 | shadow(sub (&) { no strict 'refs'; *{$name} = shift; }); |
621 | |
622 | So in the case of a C<method foo { ... }>, this call would redefine C<method> |
623 | to be a subroutine that exports 'sub foo' as the (munged) contents of C<{...}>. |
624 | |
625 | The case of an anonymous method is also cute: |
626 | |
627 | shadow(sub (&) { shift }); |
628 | |
629 | This means that |
630 | |
631 | my $meth = method () { ... }; |
632 | |
633 | is rewritten with C<method> taking the codeblock, and returning it as is to become |
634 | the value of C<$meth>. |
635 | |
636 | =head4 C<get_curstash_name> |
637 | |
638 | This returns the package name I<currently being compiled>. |
639 | |
640 | =head4 C<shadow_sub> |
641 | |
642 | Handles the details of redefining the subroutine. |
643 | |
644 | =head1 SEE ALSO |
645 | |
646 | One of the best ways to learn C<Devel::Declare> is still to look at |
647 | modules that use it: |
648 | |
649 | L<http://cpants.perl.org/dist/used_by/Devel-Declare>. |
94caac6e |
650 | |
dcf29eb6 |
651 | =head1 AUTHORS |
94caac6e |
652 | |
502ba90e |
653 | Matt S Trout - E<lt>mst@shadowcat.co.ukE<gt> - original author |
94caac6e |
654 | |
02f5a508 |
655 | Company: http://www.shadowcat.co.uk/ |
94caac6e |
656 | Blog: http://chainsawblues.vox.com/ |
657 | |
1795217c |
658 | Florian Ragwitz E<lt>rafl@debian.orgE<gt> - maintainer |
659 | |
0df492b9 |
660 | osfameron E<lt>osfameron@cpan.orgE<gt> - first draft of documentation |
dcf29eb6 |
661 | |
107322d1 |
662 | =head1 COPYRIGHT AND LICENSE |
663 | |
09addf7a |
664 | This library is free software under the same terms as perl itself |
665 | |
107322d1 |
666 | Copyright (c) 2007, 2008, 2009 Matt S Trout |
667 | |
668 | Copyright (c) 2008, 2009 Florian Ragwitz |
94caac6e |
669 | |
09addf7a |
670 | stolen_chunk_of_toke.c based on toke.c from the perl core, which is |
671 | |
672 | Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
673 | 2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others |
94caac6e |
674 | |
675 | =cut |
676 | |
677 | 1; |