Commit | Line | Data |
e4783b1c |
1 | package NEXT; |
ccea220c |
2 | $VERSION = '0.61'; |
e4783b1c |
3 | use Carp; |
4 | use strict; |
5dd54fb4 |
5 | use overload (); |
e4783b1c |
6 | |
52138ef3 |
7 | sub NEXT::ELSEWHERE::ancestors |
e4783b1c |
8 | { |
13021a80 |
9 | my @inlist = shift; |
e4783b1c |
10 | my @outlist = (); |
13021a80 |
11 | while (my $next = shift @inlist) { |
12 | push @outlist, $next; |
e4783b1c |
13 | no strict 'refs'; |
14 | unshift @inlist, @{"$outlist[-1]::ISA"}; |
15 | } |
16 | return @outlist; |
17 | } |
18 | |
bf5734d4 |
19 | sub NEXT::ELSEWHERE::ordered_ancestors |
20 | { |
21 | my @inlist = shift; |
22 | my @outlist = (); |
23 | while (my $next = shift @inlist) { |
24 | push @outlist, $next; |
25 | no strict 'refs'; |
26 | push @inlist, @{"$outlist[-1]::ISA"}; |
27 | } |
28 | return sort { $a->isa($b) ? -1 |
29 | : $b->isa($a) ? +1 |
30 | : 0 } @outlist; |
31 | } |
32 | |
597fc7a0 |
33 | sub NEXT::ELSEWHERE::buildAUTOLOAD |
e4783b1c |
34 | { |
597fc7a0 |
35 | my $autoload_name = caller() . '::AUTOLOAD'; |
36 | |
37 | no strict 'refs'; |
38 | *{$autoload_name} = sub { |
39 | my ($self) = @_; |
40 | my $depth = 1; |
41 | until (((caller($depth))[3]||q{}) !~ /^\(eval\)$/) { $depth++ } |
42 | my $caller = (caller($depth))[3]; |
43 | my $wanted = $NEXT::AUTOLOAD || $autoload_name; |
44 | undef $NEXT::AUTOLOAD; |
45 | my ($caller_class, $caller_method) = $caller =~ m{(.*)::(.*)}g; |
46 | my ($wanted_class, $wanted_method) = $wanted =~ m{(.*)::(.*)}g; |
47 | croak "Can't call $wanted from $caller" |
48 | unless $caller_method eq $wanted_method; |
49 | |
50 | my $key = ref $self && overload::Overloaded($self) |
51 | ? overload::StrVal($self) : $self; |
52 | |
53 | local ($NEXT::NEXT{$key,$wanted_method}, $NEXT::SEEN) = |
54 | ($NEXT::NEXT{$key,$wanted_method}, $NEXT::SEEN); |
55 | |
56 | unless ($NEXT::NEXT{$key,$wanted_method}) { |
57 | my @forebears = |
58 | NEXT::ELSEWHERE::ancestors ref $self || $self, |
59 | $wanted_class; |
60 | while (@forebears) { |
61 | last if shift @forebears eq $caller_class |
62 | } |
63 | no strict 'refs'; |
64 | @{$NEXT::NEXT{$key,$wanted_method}} = |
65 | map { *{"${_}::$caller_method"}{CODE}||() } @forebears |
66 | unless $wanted_method eq 'AUTOLOAD'; |
67 | @{$NEXT::NEXT{$key,$wanted_method}} = |
68 | map { (*{"${_}::AUTOLOAD"}{CODE}) ? "${_}::AUTOLOAD" : ()} @forebears |
69 | unless @{$NEXT::NEXT{$key,$wanted_method}||[]}; |
70 | $NEXT::SEEN->{$key,*{$caller}{CODE}}++; |
71 | } |
72 | my $call_method = shift @{$NEXT::NEXT{$key,$wanted_method}}; |
73 | while ($wanted_class =~ /^NEXT\b.*\b(UNSEEN|DISTINCT)\b/ |
74 | && defined $call_method |
75 | && $NEXT::SEEN->{$key,$call_method}++) { |
76 | $call_method = shift @{$NEXT::NEXT{$key,$wanted_method}}; |
77 | } |
78 | unless (defined $call_method) { |
79 | return unless $wanted_class =~ /^NEXT:.*:ACTUAL/; |
80 | (local $Carp::CarpLevel)++; |
81 | croak qq(Can't locate object method "$wanted_method" ), |
82 | qq(via package "$caller_class"); |
83 | }; |
84 | return $self->$call_method(@_[1..$#_]) if ref $call_method eq 'CODE'; |
85 | no strict 'refs'; |
86 | ($wanted_method=${$caller_class."::AUTOLOAD"}) =~ s/.*::// |
87 | if $wanted_method eq 'AUTOLOAD'; |
88 | $$call_method = $caller_class."::NEXT::".$wanted_method; |
89 | return $call_method->(@_); |
90 | }; |
e4783b1c |
91 | } |
92 | |
13021a80 |
93 | no strict 'vars'; |
597fc7a0 |
94 | package NEXT; NEXT::ELSEWHERE::buildAUTOLOAD(); |
95 | package NEXT::UNSEEN; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
96 | package NEXT::DISTINCT; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
97 | package NEXT::ACTUAL; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
98 | package NEXT::ACTUAL::UNSEEN; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
99 | package NEXT::ACTUAL::DISTINCT; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
100 | package NEXT::UNSEEN::ACTUAL; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
101 | package NEXT::DISTINCT::ACTUAL; @ISA = 'NEXT'; NEXT::ELSEWHERE::buildAUTOLOAD(); |
102 | |
103 | package EVERY; |
104 | |
105 | sub EVERY::ELSEWHERE::buildAUTOLOAD { |
106 | my $autoload_name = caller() . '::AUTOLOAD'; |
107 | |
108 | no strict 'refs'; |
109 | *{$autoload_name} = sub { |
110 | my ($self) = @_; |
111 | my $depth = 1; |
112 | until (((caller($depth))[3]||q{}) !~ /^\(eval\)$/) { $depth++ } |
113 | my $caller = (caller($depth))[3]; |
114 | my $wanted = $EVERY::AUTOLOAD || $autoload_name; |
115 | undef $EVERY::AUTOLOAD; |
116 | my ($wanted_class, $wanted_method) = $wanted =~ m{(.*)::(.*)}g; |
117 | |
118 | my $key = ref($self) && overload::Overloaded($self) |
119 | ? overload::StrVal($self) : $self; |
120 | |
121 | local $NEXT::ALREADY_IN_EVERY{$key,$wanted_method} = |
122 | $NEXT::ALREADY_IN_EVERY{$key,$wanted_method}; |
123 | |
124 | return if $NEXT::ALREADY_IN_EVERY{$key,$wanted_method}++; |
125 | |
126 | my @forebears = NEXT::ELSEWHERE::ordered_ancestors ref $self || $self, |
127 | $wanted_class; |
128 | @forebears = reverse @forebears if $wanted_class =~ /\bLAST\b/; |
129 | no strict 'refs'; |
130 | my %seen; |
131 | my @every = map { my $sub = "${_}::$wanted_method"; |
132 | !*{$sub}{CODE} || $seen{$sub}++ ? () : $sub |
133 | } @forebears |
134 | unless $wanted_method eq 'AUTOLOAD'; |
135 | |
136 | my $want = wantarray; |
137 | if (@every) { |
138 | if ($want) { |
139 | return map {($_, [$self->$_(@_[1..$#_])])} @every; |
140 | } |
141 | elsif (defined $want) { |
142 | return { map {($_, scalar($self->$_(@_[1..$#_])))} |
143 | @every |
144 | }; |
145 | } |
146 | else { |
147 | $self->$_(@_[1..$#_]) for @every; |
148 | return; |
149 | } |
150 | } |
151 | |
152 | @every = map { my $sub = "${_}::AUTOLOAD"; |
153 | !*{$sub}{CODE} || $seen{$sub}++ ? () : "${_}::AUTOLOAD" |
154 | } @forebears; |
155 | if ($want) { |
156 | return map { $$_ = ref($self)."::EVERY::".$wanted_method; |
157 | ($_, [$self->$_(@_[1..$#_])]); |
158 | } @every; |
159 | } |
160 | elsif (defined $want) { |
161 | return { map { $$_ = ref($self)."::EVERY::".$wanted_method; |
162 | ($_, scalar($self->$_(@_[1..$#_]))) |
163 | } @every |
164 | }; |
165 | } |
166 | else { |
167 | for (@every) { |
168 | $$_ = ref($self)."::EVERY::".$wanted_method; |
169 | $self->$_(@_[1..$#_]); |
170 | } |
171 | return; |
172 | } |
173 | }; |
bf5734d4 |
174 | } |
175 | |
597fc7a0 |
176 | package EVERY::LAST; @ISA = 'EVERY'; EVERY::ELSEWHERE::buildAUTOLOAD(); |
177 | package EVERY; @ISA = 'NEXT'; EVERY::ELSEWHERE::buildAUTOLOAD(); |
13021a80 |
178 | |
e4783b1c |
179 | 1; |
180 | |
181 | __END__ |
182 | |
183 | =head1 NAME |
184 | |
bf5734d4 |
185 | NEXT.pm - Provide a pseudo-class NEXT (et al) that allows method redispatch |
e4783b1c |
186 | |
187 | |
188 | =head1 SYNOPSIS |
189 | |
13021a80 |
190 | use NEXT; |
e4783b1c |
191 | |
13021a80 |
192 | package A; |
193 | sub A::method { print "$_[0]: A method\n"; $_[0]->NEXT::method() } |
194 | sub A::DESTROY { print "$_[0]: A dtor\n"; $_[0]->NEXT::DESTROY() } |
e4783b1c |
195 | |
13021a80 |
196 | package B; |
197 | use base qw( A ); |
198 | sub B::AUTOLOAD { print "$_[0]: B AUTOLOAD\n"; $_[0]->NEXT::AUTOLOAD() } |
199 | sub B::DESTROY { print "$_[0]: B dtor\n"; $_[0]->NEXT::DESTROY() } |
e4783b1c |
200 | |
13021a80 |
201 | package C; |
202 | sub C::method { print "$_[0]: C method\n"; $_[0]->NEXT::method() } |
203 | sub C::AUTOLOAD { print "$_[0]: C AUTOLOAD\n"; $_[0]->NEXT::AUTOLOAD() } |
204 | sub C::DESTROY { print "$_[0]: C dtor\n"; $_[0]->NEXT::DESTROY() } |
e4783b1c |
205 | |
13021a80 |
206 | package D; |
207 | use base qw( B C ); |
208 | sub D::method { print "$_[0]: D method\n"; $_[0]->NEXT::method() } |
209 | sub D::AUTOLOAD { print "$_[0]: D AUTOLOAD\n"; $_[0]->NEXT::AUTOLOAD() } |
210 | sub D::DESTROY { print "$_[0]: D dtor\n"; $_[0]->NEXT::DESTROY() } |
e4783b1c |
211 | |
13021a80 |
212 | package main; |
e4783b1c |
213 | |
13021a80 |
214 | my $obj = bless {}, "D"; |
e4783b1c |
215 | |
13021a80 |
216 | $obj->method(); # Calls D::method, A::method, C::method |
217 | $obj->missing_method(); # Calls D::AUTOLOAD, B::AUTOLOAD, C::AUTOLOAD |
e4783b1c |
218 | |
13021a80 |
219 | # Clean-up calls D::DESTROY, B::DESTROY, A::DESTROY, C::DESTROY |
e4783b1c |
220 | |
221 | |
bf5734d4 |
222 | |
e4783b1c |
223 | =head1 DESCRIPTION |
224 | |
225 | NEXT.pm adds a pseudoclass named C<NEXT> to any program |
e23eab12 |
226 | that uses it. If a method C<m> calls C<$self-E<gt>NEXT::m()>, the call to |
e4783b1c |
227 | C<m> is redispatched as if the calling method had not originally been found. |
228 | |
e23eab12 |
229 | In other words, a call to C<$self-E<gt>NEXT::m()> resumes the depth-first, |
55a1c97c |
230 | left-to-right search of C<$self>'s class hierarchy that resulted in the |
231 | original call to C<m>. |
232 | |
e23eab12 |
233 | Note that this is not the same thing as C<$self-E<gt>SUPER::m()>, which |
55a1c97c |
234 | begins a new dispatch that is restricted to searching the ancestors |
e23eab12 |
235 | of the current class. C<$self-E<gt>NEXT::m()> can backtrack |
55a1c97c |
236 | past the current class -- to look for a suitable method in other |
e23eab12 |
237 | ancestors of C<$self> -- whereas C<$self-E<gt>SUPER::m()> cannot. |
e4783b1c |
238 | |
239 | A typical use would be in the destructors of a class hierarchy, |
240 | as illustrated in the synopsis above. Each class in the hierarchy |
241 | has a DESTROY method that performs some class-specific action |
242 | and then redispatches the call up the hierarchy. As a result, |
243 | when an object of class D is destroyed, the destructors of I<all> |
244 | its parent classes are called (in depth-first, left-to-right order). |
245 | |
246 | Another typical use of redispatch would be in C<AUTOLOAD>'ed methods. |
247 | If such a method determined that it was not able to handle a |
248 | particular call, it might choose to redispatch that call, in the |
249 | hope that some other C<AUTOLOAD> (above it, or to its left) might |
250 | do better. |
251 | |
13021a80 |
252 | By default, if a redispatch attempt fails to find another method |
253 | elsewhere in the objects class hierarchy, it quietly gives up and does |
3c4b39be |
254 | nothing (but see L<"Enforcing redispatch">). This gracious acquiescence |
13021a80 |
255 | is also unlike the (generally annoying) behaviour of C<SUPER>, which |
256 | throws an exception if it cannot redispatch. |
257 | |
e4783b1c |
258 | Note that it is a fatal error for any method (including C<AUTOLOAD>) |
13021a80 |
259 | to attempt to redispatch any method that does not have the |
260 | same name. For example: |
261 | |
262 | sub D::oops { print "oops!\n"; $_[0]->NEXT::other_method() } |
263 | |
264 | |
265 | =head2 Enforcing redispatch |
266 | |
267 | It is possible to make C<NEXT> redispatch more demandingly (i.e. like |
268 | C<SUPER> does), so that the redispatch throws an exception if it cannot |
269 | find a "next" method to call. |
270 | |
271 | To do this, simple invoke the redispatch as: |
272 | |
273 | $self->NEXT::ACTUAL::method(); |
274 | |
275 | rather than: |
276 | |
277 | $self->NEXT::method(); |
278 | |
279 | The C<ACTUAL> tells C<NEXT> that there must actually be a next method to call, |
280 | or it should throw an exception. |
281 | |
282 | C<NEXT::ACTUAL> is most commonly used in C<AUTOLOAD> methods, as a means to |
283 | decline an C<AUTOLOAD> request, but preserve the normal exception-on-failure |
284 | semantics: |
285 | |
286 | sub AUTOLOAD { |
287 | if ($AUTOLOAD =~ /foo|bar/) { |
288 | # handle here |
289 | } |
290 | else { # try elsewhere |
291 | shift()->NEXT::ACTUAL::AUTOLOAD(@_); |
292 | } |
293 | } |
294 | |
295 | By using C<NEXT::ACTUAL>, if there is no other C<AUTOLOAD> to handle the |
296 | method call, an exception will be thrown (as usually happens in the absence of |
297 | a suitable C<AUTOLOAD>). |
298 | |
299 | |
300 | =head2 Avoiding repetitions |
301 | |
302 | If C<NEXT> redispatching is used in the methods of a "diamond" class hierarchy: |
303 | |
304 | # A B |
305 | # / \ / |
306 | # C D |
307 | # \ / |
308 | # E |
309 | |
310 | use NEXT; |
311 | |
312 | package A; |
313 | sub foo { print "called A::foo\n"; shift->NEXT::foo() } |
314 | |
315 | package B; |
316 | sub foo { print "called B::foo\n"; shift->NEXT::foo() } |
317 | |
318 | package C; @ISA = qw( A ); |
319 | sub foo { print "called C::foo\n"; shift->NEXT::foo() } |
320 | |
321 | package D; @ISA = qw(A B); |
322 | sub foo { print "called D::foo\n"; shift->NEXT::foo() } |
323 | |
324 | package E; @ISA = qw(C D); |
325 | sub foo { print "called E::foo\n"; shift->NEXT::foo() } |
326 | |
327 | E->foo(); |
328 | |
329 | then derived classes may (re-)inherit base-class methods through two or |
330 | more distinct paths (e.g. in the way C<E> inherits C<A::foo> twice -- |
331 | through C<C> and C<D>). In such cases, a sequence of C<NEXT> redispatches |
332 | will invoke the multiply inherited method as many times as it is |
333 | inherited. For example, the above code prints: |
334 | |
335 | called E::foo |
336 | called C::foo |
337 | called A::foo |
338 | called D::foo |
339 | called A::foo |
340 | called B::foo |
341 | |
342 | (i.e. C<A::foo> is called twice). |
343 | |
344 | In some cases this I<may> be the desired effect within a diamond hierarchy, |
345 | but in others (e.g. for destructors) it may be more appropriate to |
346 | call each method only once during a sequence of redispatches. |
347 | |
348 | To cover such cases, you can redispatch methods via: |
349 | |
52138ef3 |
350 | $self->NEXT::DISTINCT::method(); |
13021a80 |
351 | |
352 | rather than: |
353 | |
354 | $self->NEXT::method(); |
355 | |
52138ef3 |
356 | This causes the redispatcher to only visit each distinct C<method> method |
357 | once. That is, to skip any classes in the hierarchy that it has |
358 | already visited during redispatch. So, for example, if the |
13021a80 |
359 | previous example were rewritten: |
360 | |
361 | package A; |
52138ef3 |
362 | sub foo { print "called A::foo\n"; shift->NEXT::DISTINCT::foo() } |
13021a80 |
363 | |
364 | package B; |
52138ef3 |
365 | sub foo { print "called B::foo\n"; shift->NEXT::DISTINCT::foo() } |
13021a80 |
366 | |
367 | package C; @ISA = qw( A ); |
52138ef3 |
368 | sub foo { print "called C::foo\n"; shift->NEXT::DISTINCT::foo() } |
13021a80 |
369 | |
370 | package D; @ISA = qw(A B); |
52138ef3 |
371 | sub foo { print "called D::foo\n"; shift->NEXT::DISTINCT::foo() } |
13021a80 |
372 | |
373 | package E; @ISA = qw(C D); |
52138ef3 |
374 | sub foo { print "called E::foo\n"; shift->NEXT::DISTINCT::foo() } |
13021a80 |
375 | |
376 | E->foo(); |
377 | |
378 | then it would print: |
379 | |
380 | called E::foo |
381 | called C::foo |
382 | called A::foo |
383 | called D::foo |
384 | called B::foo |
385 | |
52138ef3 |
386 | and omit the second call to C<A::foo> (since it would not be distinct |
387 | from the first call to C<A::foo>). |
13021a80 |
388 | |
389 | Note that you can also use: |
390 | |
52138ef3 |
391 | $self->NEXT::DISTINCT::ACTUAL::method(); |
13021a80 |
392 | |
393 | or: |
394 | |
52138ef3 |
395 | $self->NEXT::ACTUAL::DISTINCT::method(); |
e4783b1c |
396 | |
13021a80 |
397 | to get both unique invocation I<and> exception-on-failure. |
e4783b1c |
398 | |
52138ef3 |
399 | Note that, for historical compatibility, you can also use |
400 | C<NEXT::UNSEEN> instead of C<NEXT::DISTINCT>. |
e4783b1c |
401 | |
bf5734d4 |
402 | |
403 | =head2 Invoking all versions of a method with a single call |
404 | |
405 | Yet another pseudo-class that NEXT.pm provides is C<EVERY>. |
406 | Its behaviour is considerably simpler than that of the C<NEXT> family. |
407 | A call to: |
408 | |
409 | $obj->EVERY::foo(); |
410 | |
411 | calls I<every> method named C<foo> that the object in C<$obj> has inherited. |
412 | That is: |
413 | |
414 | use NEXT; |
415 | |
416 | package A; @ISA = qw(B D X); |
417 | sub foo { print "A::foo " } |
418 | |
419 | package B; @ISA = qw(D X); |
420 | sub foo { print "B::foo " } |
421 | |
422 | package X; @ISA = qw(D); |
423 | sub foo { print "X::foo " } |
424 | |
425 | package D; |
426 | sub foo { print "D::foo " } |
427 | |
428 | package main; |
429 | |
430 | my $obj = bless {}, 'A'; |
431 | $obj->EVERY::foo(); # prints" A::foo B::foo X::foo D::foo |
432 | |
433 | Prefixing a method call with C<EVERY::> causes every method in the |
434 | object's hierarchy with that name to be invoked. As the above example |
435 | illustrates, they are not called in Perl's usual "left-most-depth-first" |
436 | order. Instead, they are called "breadth-first-dependency-wise". |
437 | |
438 | That means that the inheritance tree of the object is traversed breadth-first |
439 | and the resulting order of classes is used as the sequence in which methods |
440 | are called. However, that sequence is modified by imposing a rule that the |
3c4b39be |
441 | appropriate method of a derived class must be called before the same method of |
bf5734d4 |
442 | any ancestral class. That's why, in the above example, C<X::foo> is called |
443 | before C<D::foo>, even though C<D> comes before C<X> in C<@B::ISA>. |
444 | |
445 | In general, there's no need to worry about the order of calls. They will be |
446 | left-to-right, breadth-first, most-derived-first. This works perfectly for |
447 | most inherited methods (including destructors), but is inappropriate for |
448 | some kinds of methods (such as constructors, cloners, debuggers, and |
449 | initializers) where it's more appropriate that the least-derived methods be |
450 | called first (as more-derived methods may rely on the behaviour of their |
451 | "ancestors"). In that case, instead of using the C<EVERY> pseudo-class: |
452 | |
453 | $obj->EVERY::foo(); # prints" A::foo B::foo X::foo D::foo |
454 | |
455 | you can use the C<EVERY::LAST> pseudo-class: |
456 | |
457 | $obj->EVERY::LAST::foo(); # prints" D::foo X::foo B::foo A::foo |
458 | |
459 | which reverses the order of method call. |
460 | |
461 | Whichever version is used, the actual methods are called in the same |
462 | context (list, scalar, or void) as the original call via C<EVERY>, and return: |
463 | |
464 | =over |
465 | |
466 | =item * |
467 | |
468 | A hash of array references in list context. Each entry of the hash has the |
469 | fully qualified method name as its key and a reference to an array containing |
470 | the method's list-context return values as its value. |
471 | |
472 | =item * |
473 | |
474 | A reference to a hash of scalar values in scalar context. Each entry of the hash has the |
475 | fully qualified method name as its key and the method's scalar-context return values as its value. |
476 | |
477 | =item * |
478 | |
479 | Nothing in void context (obviously). |
480 | |
481 | =back |
482 | |
483 | =head2 Using C<EVERY> methods |
484 | |
485 | The typical way to use an C<EVERY> call is to wrap it in another base |
486 | method, that all classes inherit. For example, to ensure that every |
487 | destructor an object inherits is actually called (as opposed to just the |
488 | left-most-depth-first-est one): |
489 | |
490 | package Base; |
491 | sub DESTROY { $_[0]->EVERY::Destroy } |
492 | |
493 | package Derived1; |
494 | use base 'Base'; |
495 | sub Destroy {...} |
496 | |
497 | package Derived2; |
498 | use base 'Base', 'Derived1'; |
499 | sub Destroy {...} |
500 | |
501 | et cetera. Every derived class than needs its own clean-up |
502 | behaviour simply adds its own C<Destroy> method (I<not> a C<DESTROY> method), |
503 | which the call to C<EVERY::LAST::Destroy> in the inherited destructor |
504 | then correctly picks up. |
505 | |
506 | Likewise, to create a class hierarchy in which every initializer inherited by |
507 | a new object is invoked: |
508 | |
509 | package Base; |
510 | sub new { |
511 | my ($class, %args) = @_; |
512 | my $obj = bless {}, $class; |
513 | $obj->EVERY::LAST::Init(\%args); |
514 | } |
515 | |
516 | package Derived1; |
517 | use base 'Base'; |
518 | sub Init { |
519 | my ($argsref) = @_; |
520 | ... |
521 | } |
522 | |
523 | package Derived2; |
524 | use base 'Base', 'Derived1'; |
525 | sub Init { |
526 | my ($argsref) = @_; |
527 | ... |
528 | } |
529 | |
530 | et cetera. Every derived class than needs some additional initialization |
531 | behaviour simply adds its own C<Init> method (I<not> a C<new> method), |
532 | which the call to C<EVERY::LAST::Init> in the inherited constructor |
533 | then correctly picks up. |
534 | |
535 | |
e4783b1c |
536 | =head1 AUTHOR |
537 | |
538 | Damian Conway (damian@conway.org) |
539 | |
540 | =head1 BUGS AND IRRITATIONS |
541 | |
542 | Because it's a module, not an integral part of the interpreter, NEXT.pm |
543 | has to guess where the surrounding call was found in the method |
544 | look-up sequence. In the presence of diamond inheritance patterns |
545 | it occasionally guesses wrong. |
546 | |
547 | It's also too slow (despite caching). |
548 | |
549 | Comment, suggestions, and patches welcome. |
550 | |
551 | =head1 COPYRIGHT |
552 | |
55a1c97c |
553 | Copyright (c) 2000-2001, Damian Conway. All Rights Reserved. |
e4783b1c |
554 | This module is free software. It may be used, redistributed |
55a1c97c |
555 | and/or modified under the same terms as Perl itself. |