1 package Attribute::Handlers;
10 my ($pkg, $ref, $type) = @_;
11 return $symcache{$pkg,$ref} if $symcache{$pkg,$ref};
14 foreach my $sym ( values %{$pkg."::"} ) {
15 return $symcache{$pkg,$ref} = \$sym
16 if *{$sym}{$type} && *{$sym}{$type} == $ref;
21 VAR => [qw[SCALAR ARRAY HASH]],
22 ANY => [qw[SCALAR ARRAY HASH CODE]],
23 "" => [qw[SCALAR ARRAY HASH CODE]],
24 SCALAR => [qw[SCALAR]],
33 my %sigil = (SCALAR=>'$', ARRAY=>'@', HASH=>'%');
41 my @global_phases = qw(BEGIN CHECK INIT END);
44 croak "Usage: use $_[0] autotie => {AttrName => TieClassName,...}";
47 my $qual_id = qr/^[_a-z]\w*(::[_a-z]\w*)*$/i;
51 return unless $class eq "Attribute::Handlers";
54 if ($cmd =~ /^autotie((?:ref)?)$/) {
55 my $tiedata = ($1 ? '$ref, ' : '') . '@$data';
57 _usage_AH_ $class unless ref($mapping) eq 'HASH';
58 while (my($attr, $tieclass) = each %$mapping) {
59 $tieclass =~ s/^([_a-z]\w*(::[_a-z]\w*)*)(.*)/$1/is;
61 _usage_AH_ $class unless $attr =~ $qual_id
62 && $tieclass =~ $qual_id
63 && eval "use base $tieclass; 1";
64 if ($tieclass->isa('Exporter')) {
65 local $Exporter::ExportLevel = 2;
66 $tieclass->import(eval $args);
68 $attr =~ s/__CALLER__/caller(1)/e;
69 $attr = caller()."::".$attr unless $attr =~ /::/;
71 sub $attr : ATTR(VAR) {
72 my (\$ref, \$data) = \@_[2,4];
73 my \$was_arrayref = ref \$data eq 'ARRAY';
74 \$data = [ \$data ] unless \$was_arrayref;
75 my \$type = ref(\$ref)||"value (".(\$ref||"<undef>").")";
76 (\$type eq 'SCALAR')? tie \$\$ref,'$tieclass',$tiedata
77 :(\$type eq 'ARRAY') ? tie \@\$ref,'$tieclass',$tiedata
78 :(\$type eq 'HASH') ? tie \%\$ref,'$tieclass',$tiedata
79 : die "Can't autotie a \$type\n"
81 } or die "Internal error: $@";
85 croak "Can't understand $_";
89 sub _resolve_lastattr {
90 return unless $lastattr{ref};
91 my $sym = findsym @lastattr{'pkg','ref'}
92 or die "Internal error: $lastattr{pkg} symbol went missing";
93 my $name = *{$sym}{NAME};
94 warn "Declaration of $name attribute in package $lastattr{pkg} may clash with future reserved word\n"
95 if $^W and $name !~ /[A-Z]/;
96 foreach ( @{$validtype{$lastattr{type}}} ) {
97 *{"$lastattr{pkg}::_ATTR_${_}_${name}"} = $lastattr{ref};
103 my ($class) = $AUTOLOAD =~ m/(.*)::/g;
104 $AUTOLOAD =~ m/_ATTR_(.*?)_(.*)/ or
105 croak "Can't locate class method '$AUTOLOAD' via package '$class'";
106 croak "Attribute handler '$2' doesn't handle $1 attributes";
111 my $builtin = qr/lvalue|method|locked|unique|shared/;
113 sub _gen_handler_AH_() {
116 my ($pkg, $ref, @attrs) = @_;
118 my ($attr, $data) = /^([a-z_]\w*)(?:[(](.*)[)])?$/is or next;
119 if ($attr eq 'ATTR') {
121 $raw{$ref} = $data =~ s/\s*,?\s*RAWDATA\s*,?\s*//;
122 $phase{$ref}{BEGIN} = 1
123 if $data =~ s/\s*,?\s*(BEGIN)\s*,?\s*//;
124 $phase{$ref}{INIT} = 1
125 if $data =~ s/\s*,?\s*(INIT)\s*,?\s*//;
126 $phase{$ref}{END} = 1
127 if $data =~ s/\s*,?\s*(END)\s*,?\s*//;
128 $phase{$ref}{CHECK} = 1
129 if $data =~ s/\s*,?\s*(CHECK)\s*,?\s*//
130 || ! keys %{$phase{$ref}};
131 # Added for cleanup to not pollute next call.
133 croak "Can't have two ATTR specifiers on one subroutine"
135 croak "Bad attribute type: ATTR($data)"
136 unless $validtype{$data};
137 %lastattr=(pkg=>$pkg,ref=>$ref,type=>$data);
141 my $handler = $pkg->can("_ATTR_${type}_${attr}");
142 next unless $handler;
143 my $decl = [$pkg, $ref, $attr, $data,
144 $raw{$handler}, $phase{$handler}];
145 foreach my $gphase (@global_phases) {
146 _apply_handler_AH_($decl,$gphase)
147 if $global_phases{$gphase} <= $global_phase;
149 if ($global_phase != 0) {
150 # if _gen_handler_AH_ is being called after
151 # CHECK it's for a lexical, so make sure
152 # it didn't want to run anything later
154 local $Carp::CarpLevel = 2;
155 carp "Won't be able to apply END handler"
156 if $phase{$handler}{END};
159 push @declarations, $decl
164 return grep {defined && !/$builtin/} @attrs;
168 *{"Attribute::Handlers::UNIVERSAL::MODIFY_${_}_ATTRIBUTES"} =
169 _gen_handler_AH_ foreach @{$validtype{ANY}};
170 push @UNIVERSAL::ISA, 'Attribute::Handlers::UNIVERSAL'
171 unless grep /^Attribute::Handlers::UNIVERSAL$/, @UNIVERSAL::ISA;
173 sub _apply_handler_AH_ {
174 my ($declaration, $phase) = @_;
175 my ($pkg, $ref, $attr, $data, $raw, $handlerphase) = @$declaration;
176 return unless $handlerphase->{$phase};
177 # print STDERR "Handling $attr on $ref in $phase with [$data]\n";
179 my $handler = "_ATTR_${type}_${attr}";
180 my $sym = findsym($pkg, $ref);
181 $sym ||= $type eq 'CODE' ? 'ANON' : 'LEXICAL';
183 my $evaled = !$raw && eval("package $pkg; no warnings;
184 local \$SIG{__WARN__}=sub{die}; [$data]");
185 $data = ($evaled && $data =~ /^\s*\[/) ? [$evaled]
186 : ($evaled) ? $evaled
189 (ref $sym eq 'GLOB' ? *{$sym}{ref $ref}||$ref : $ref),
191 (@$data>1? $data : $data->[0]),
202 _apply_handler_AH_($_,'CHECK') foreach @declarations;
207 _apply_handler_AH_($_,'INIT') foreach @declarations
211 END { $global_phase++; _apply_handler_AH_($_,'END') foreach @declarations }
218 Attribute::Handlers - Simpler definition of attribute handlers
222 This document describes version 0.78 of Attribute::Handlers,
223 released October 5, 2002.
229 use Attribute::Handlers;
230 no warnings 'redefine';
233 sub Good : ATTR(SCALAR) {
234 my ($package, $symbol, $referent, $attr, $data) = @_;
236 # Invoked for any scalar variable with a :Good attribute,
237 # provided the variable was declared in MyClass (or
238 # a derived class) or typed to MyClass.
240 # Do whatever to $referent here (executed in CHECK phase).
244 sub Bad : ATTR(SCALAR) {
245 # Invoked for any scalar variable with a :Bad attribute,
246 # provided the variable was declared in MyClass (or
247 # a derived class) or typed to MyClass.
251 sub Good : ATTR(ARRAY) {
252 # Invoked for any array variable with a :Good attribute,
253 # provided the variable was declared in MyClass (or
254 # a derived class) or typed to MyClass.
258 sub Good : ATTR(HASH) {
259 # Invoked for any hash variable with a :Good attribute,
260 # provided the variable was declared in MyClass (or
261 # a derived class) or typed to MyClass.
265 sub Ugly : ATTR(CODE) {
266 # Invoked for any subroutine declared in MyClass (or a
267 # derived class) with an :Ugly attribute.
272 # Invoked for any scalar, array, hash, or subroutine
273 # with an :Omni attribute, provided the variable or
274 # subroutine was declared in MyClass (or a derived class)
275 # or the variable was typed to MyClass.
276 # Use ref($_[2]) to determine what kind of referent it was.
281 use Attribute::Handlers autotie => { Cycle => Tie::Cycle };
283 my $next : Cycle(['A'..'Z']);
288 This module, when inherited by a package, allows that package's class to
289 define attribute handler subroutines for specific attributes. Variables
290 and subroutines subsequently defined in that package, or in packages
291 derived from that package may be given attributes with the same names as
292 the attribute handler subroutines, which will then be called in one of
293 the compilation phases (i.e. in a C<BEGIN>, C<CHECK>, C<INIT>, or C<END>
294 block). (C<UNITCHECK> blocks don't correspond to a global compilation
295 phase, so they can't be specified here.)
297 To create a handler, define it as a subroutine with the same name as
298 the desired attribute, and declare the subroutine itself with the
299 attribute C<:ATTR>. For example:
302 use Attribute::Handlers;
305 my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
308 *{$symbol}{NAME}, " ",
309 "($referent) ", "was just declared ",
310 "and ascribed the ${attr} attribute ",
311 "with data ($data)\n",
315 This creates a handler for the attribute C<:Loud> in the class LoudDecl.
316 Thereafter, any subroutine declared with a C<:Loud> attribute in the class
323 causes the above handler to be invoked, and passed:
329 the name of the package into which it was declared;
333 a reference to the symbol table entry (typeglob) containing the subroutine;
337 a reference to the subroutine;
341 the name of the attribute;
345 any data associated with that attribute;
349 the name of the phase in which the handler is being invoked.
353 Likewise, declaring any variables with the C<:Loud> attribute within the
362 will cause the handler to be called with a similar argument list (except,
363 of course, that C<$_[2]> will be a reference to the variable).
365 The package name argument will typically be the name of the class into
366 which the subroutine was declared, but it may also be the name of a derived
367 class (since handlers are inherited).
369 If a lexical variable is given an attribute, there is no symbol table to
370 which it belongs, so the symbol table argument (C<$_[1]>) is set to the
371 string C<'LEXICAL'> in that case. Likewise, ascribing an attribute to
372 an anonymous subroutine results in a symbol table argument of C<'ANON'>.
374 The data argument passes in the value (if any) associated with the
375 attribute. For example, if C<&foo> had been declared:
377 sub foo :Loud("turn it up to 11, man!") {...}
379 then the string C<"turn it up to 11, man!"> would be passed as the
382 Attribute::Handlers makes strenuous efforts to convert
383 the data argument (C<$_[4]>) to a useable form before passing it to
384 the handler (but see L<"Non-interpretive attribute handlers">).
385 For example, all of these:
387 sub foo :Loud(till=>ears=>are=>bleeding) {...}
388 sub foo :Loud(['till','ears','are','bleeding']) {...}
389 sub foo :Loud(qw/till ears are bleeding/) {...}
390 sub foo :Loud(qw/my, ears, are, bleeding/) {...}
391 sub foo :Loud(till,ears,are,bleeding) {...}
393 causes it to pass C<['till','ears','are','bleeding']> as the handler's
394 data argument. However, if the data can't be parsed as valid Perl, then
395 it is passed as an uninterpreted string. For example:
397 sub foo :Loud(my,ears,are,bleeding) {...}
398 sub foo :Loud(qw/my ears are bleeding) {...}
400 cause the strings C<'my,ears,are,bleeding'> and C<'qw/my ears are bleeding'>
401 respectively to be passed as the data argument.
403 If the attribute has only a single associated scalar data value, that value is
404 passed as a scalar. If multiple values are associated, they are passed as an
405 array reference. If no value is associated with the attribute, C<undef> is
409 =head2 Typed lexicals
411 Regardless of the package in which it is declared, if a lexical variable is
412 ascribed an attribute, the handler that is invoked is the one belonging to
413 the package to which it is typed. For example, the following declarations:
417 my LoudDecl $loudobj : Loud;
418 my LoudDecl @loudobjs : Loud;
419 my LoudDecl %loudobjex : Loud;
421 causes the LoudDecl::Loud handler to be invoked (even if OtherClass also
422 defines a handler for C<:Loud> attributes).
425 =head2 Type-specific attribute handlers
427 If an attribute handler is declared and the C<:ATTR> specifier is
428 given the name of a built-in type (C<SCALAR>, C<ARRAY>, C<HASH>, or C<CODE>),
429 the handler is only applied to declarations of that type. For example,
430 the following definition:
434 sub RealLoud :ATTR(SCALAR) { print "Yeeeeow!" }
436 creates an attribute handler that applies only to scalars:
442 my $metal : RealLoud; # invokes &LoudDecl::RealLoud
443 my @metal : RealLoud; # error: unknown attribute
444 my %metal : RealLoud; # error: unknown attribute
445 sub metal : RealLoud {...} # error: unknown attribute
447 You can, of course, declare separate handlers for these types as well
448 (but you'll need to specify C<no warnings 'redefine'> to do it quietly):
451 use Attribute::Handlers;
452 no warnings 'redefine';
454 sub RealLoud :ATTR(SCALAR) { print "Yeeeeow!" }
455 sub RealLoud :ATTR(ARRAY) { print "Urrrrrrrrrr!" }
456 sub RealLoud :ATTR(HASH) { print "Arrrrrgggghhhhhh!" }
457 sub RealLoud :ATTR(CODE) { croak "Real loud sub torpedoed" }
459 You can also explicitly indicate that a single handler is meant to be
460 used for all types of referents like so:
463 use Attribute::Handlers;
465 sub SeriousLoud :ATTR(ANY) { warn "Hearing loss imminent" }
467 (I.e. C<ATTR(ANY)> is a synonym for C<:ATTR>).
470 =head2 Non-interpretive attribute handlers
472 Occasionally the strenuous efforts Attribute::Handlers makes to convert
473 the data argument (C<$_[4]>) to a useable form before passing it to
474 the handler get in the way.
476 You can turn off that eagerness-to-help by declaring
477 an attribute handler with the keyword C<RAWDATA>. For example:
479 sub Raw : ATTR(RAWDATA) {...}
480 sub Nekkid : ATTR(SCALAR,RAWDATA) {...}
481 sub Au::Naturale : ATTR(RAWDATA,ANY) {...}
483 Then the handler makes absolutely no attempt to interpret the data it
484 receives and simply passes it as a string:
486 my $power : Raw(1..100); # handlers receives "1..100"
488 =head2 Phase-specific attribute handlers
490 By default, attribute handlers are called at the end of the compilation
491 phase (in a C<CHECK> block). This seems to be optimal in most cases because
492 most things that can be defined are defined by that point but nothing has
495 However, it is possible to set up attribute handlers that are called at
496 other points in the program's compilation or execution, by explicitly
497 stating the phase (or phases) in which you wish the attribute handler to
498 be called. For example:
500 sub Early :ATTR(SCALAR,BEGIN) {...}
501 sub Normal :ATTR(SCALAR,CHECK) {...}
502 sub Late :ATTR(SCALAR,INIT) {...}
503 sub Final :ATTR(SCALAR,END) {...}
504 sub Bookends :ATTR(SCALAR,BEGIN,END) {...}
506 As the last example indicates, a handler may be set up to be (re)called in
507 two or more phases. The phase name is passed as the handler's final argument.
509 Note that attribute handlers that are scheduled for the C<BEGIN> phase
510 are handled as soon as the attribute is detected (i.e. before any
511 subsequently defined C<BEGIN> blocks are executed).
514 =head2 Attributes as C<tie> interfaces
516 Attributes make an excellent and intuitive interface through which to tie
517 variables. For example:
519 use Attribute::Handlers;
522 sub UNIVERSAL::Cycle : ATTR(SCALAR) {
523 my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
524 $data = [ $data ] unless ref $data eq 'ARRAY';
525 tie $$referent, 'Tie::Cycle', $data;
532 my $next : Cycle('A'..'Z'); # $next is now a tied variable
538 Note that, because the C<Cycle> attribute receives its arguments in the
539 C<$data> variable, if the attribute is given a list of arguments, C<$data>
540 will consist of a single array reference; otherwise, it will consist of the
541 single argument directly. Since Tie::Cycle requires its cycling values to
542 be passed as an array reference, this means that we need to wrap
543 non-array-reference arguments in an array constructor:
545 $data = [ $data ] unless ref $data eq 'ARRAY';
547 Typically, however, things are the other way around: the tieable class expects
548 its arguments as a flattened list, so the attribute looks like:
550 sub UNIVERSAL::Cycle : ATTR(SCALAR) {
551 my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
552 my @data = ref $data eq 'ARRAY' ? @$data : $data;
553 tie $$referent, 'Tie::Whatever', @data;
557 This software pattern is so widely applicable that Attribute::Handlers
558 provides a way to automate it: specifying C<'autotie'> in the
559 C<use Attribute::Handlers> statement. So, the cycling example,
560 could also be written:
562 use Attribute::Handlers autotie => { Cycle => 'Tie::Cycle' };
568 my $next : Cycle(['A'..'Z']); # $next is now a tied variable
573 Note that we now have to pass the cycling values as an array reference,
574 since the C<autotie> mechanism passes C<tie> a list of arguments as a list
575 (as in the Tie::Whatever example), I<not> as an array reference (as in
576 the original Tie::Cycle example at the start of this section).
578 The argument after C<'autotie'> is a reference to a hash in which each key is
579 the name of an attribute to be created, and each value is the class to which
580 variables ascribed that attribute should be tied.
582 Note that there is no longer any need to import the Tie::Cycle module --
583 Attribute::Handlers takes care of that automagically. You can even pass
584 arguments to the module's C<import> subroutine, by appending them to the
585 class name. For example:
587 use Attribute::Handlers
588 autotie => { Dir => 'Tie::Dir qw(DIR_UNLINK)' };
590 If the attribute name is unqualified, the attribute is installed in the
591 current package. Otherwise it is installed in the qualifier's package:
595 use Attribute::Handlers autotie => {
596 Other::Good => Tie::SecureHash, # tie attr installed in Other::
597 Bad => Tie::Taxes, # tie attr installed in Here::
598 UNIVERSAL::Ugly => Software::Patent # tie attr installed everywhere
601 Autoties are most commonly used in the module to which they actually tie,
602 and need to export their attributes to any module that calls them. To
603 facilitate this, Attribute::Handlers recognizes a special "pseudo-class" --
604 C<__CALLER__>, which may be specified as the qualifier of an attribute:
606 package Tie::Me::Kangaroo:Down::Sport;
608 use Attribute::Handlers autotie => { '__CALLER__::Roo' => __PACKAGE__ };
610 This causes Attribute::Handlers to define the C<Roo> attribute in the package
611 that imports the Tie::Me::Kangaroo:Down::Sport module.
613 Note that it is important to quote the __CALLER__::Roo identifier because
614 a bug in perl 5.8 will refuse to parse it and cause an unknown error.
616 =head3 Passing the tied object to C<tie>
618 Occasionally it is important to pass a reference to the object being tied
619 to the TIESCALAR, TIEHASH, etc. that ties it.
621 The C<autotie> mechanism supports this too. The following code:
623 use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
624 my $var : Selfish(@args);
626 has the same effect as:
628 tie my $var, 'Tie::Selfish', @args;
630 But when C<"autotieref"> is used instead of C<"autotie">:
632 use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
633 my $var : Selfish(@args);
635 the effect is to pass the C<tie> call an extra reference to the variable
638 tie my $var, 'Tie::Selfish', \$var, @args;
644 If the class shown in L<SYNOPSIS> were placed in the MyClass.pm
645 module, then the following code:
650 my MyClass $slr :Good :Bad(1**1-1) :Omni(-vorous);
652 package SomeOtherClass;
657 sub fn :Ugly(sister) :Omni('po',tent()) {...}
658 my @arr :Good :Omni(s/cie/nt/);
659 my %hsh :Good(q/bye) :Omni(q/bus/);
662 would cause the following handlers to be invoked:
664 # my MyClass $slr :Good :Bad(1**1-1) :Omni(-vorous);
666 MyClass::Good:ATTR(SCALAR)( 'MyClass', # class
667 'LEXICAL', # no typeglob
671 'CHECK', # compiler phase
674 MyClass::Bad:ATTR(SCALAR)( 'MyClass', # class
675 'LEXICAL', # no typeglob
679 'CHECK', # compiler phase
682 MyClass::Omni:ATTR(SCALAR)( 'MyClass', # class
683 'LEXICAL', # no typeglob
686 '-vorous' # eval'd attr data
687 'CHECK', # compiler phase
691 # sub fn :Ugly(sister) :Omni('po',tent()) {...}
693 MyClass::UGLY:ATTR(CODE)( 'SomeOtherClass', # class
694 \*SomeOtherClass::fn, # typeglob
695 \&SomeOtherClass::fn, # referent
697 'sister' # eval'd attr data
698 'CHECK', # compiler phase
701 MyClass::Omni:ATTR(CODE)( 'SomeOtherClass', # class
702 \*SomeOtherClass::fn, # typeglob
703 \&SomeOtherClass::fn, # referent
705 ['po','acle'] # eval'd attr data
706 'CHECK', # compiler phase
710 # my @arr :Good :Omni(s/cie/nt/);
712 MyClass::Good:ATTR(ARRAY)( 'SomeOtherClass', # class
713 'LEXICAL', # no typeglob
717 'CHECK', # compiler phase
720 MyClass::Omni:ATTR(ARRAY)( 'SomeOtherClass', # class
721 'LEXICAL', # no typeglob
724 "" # eval'd attr data
725 'CHECK', # compiler phase
729 # my %hsh :Good(q/bye) :Omni(q/bus/);
731 MyClass::Good:ATTR(HASH)( 'SomeOtherClass', # class
732 'LEXICAL', # no typeglob
735 'q/bye' # raw attr data
736 'CHECK', # compiler phase
739 MyClass::Omni:ATTR(HASH)( 'SomeOtherClass', # class
740 'LEXICAL', # no typeglob
743 'bus' # eval'd attr data
744 'CHECK', # compiler phase
748 Installing handlers into UNIVERSAL, makes them...err..universal.
751 package Descriptions;
752 use Attribute::Handlers;
755 sub name { return $name{$_[2]}||*{$_[1]}{NAME} }
757 sub UNIVERSAL::Name :ATTR {
758 $name{$_[2]} = $_[4];
761 sub UNIVERSAL::Purpose :ATTR {
762 print STDERR "Purpose of ", &name, " is $_[4]\n";
765 sub UNIVERSAL::Unit :ATTR {
766 print STDERR &name, " measured in $_[4]\n";
773 my $capacity : Name(capacity)
774 : Purpose(to store max storage capacity for files)
780 sub foo : Purpose(to foo all data before barring it) { }
789 =item C<Bad attribute type: ATTR(%s)>
791 An attribute handler was specified with an C<:ATTR(I<ref_type>)>, but the
792 type of referent it was defined to handle wasn't one of the five permitted:
793 C<SCALAR>, C<ARRAY>, C<HASH>, C<CODE>, or C<ANY>.
795 =item C<Attribute handler %s doesn't handle %s attributes>
797 A handler for attributes of the specified name I<was> defined, but not
798 for the specified type of declaration. Typically encountered whe trying
799 to apply a C<VAR> attribute handler to a subroutine, or a C<SCALAR>
800 attribute handler to some other type of variable.
802 =item C<Declaration of %s attribute in package %s may clash with future reserved word>
804 A handler for an attributes with an all-lowercase name was declared. An
805 attribute with an all-lowercase name might have a meaning to Perl
806 itself some day, even though most don't yet. Use a mixed-case attribute
809 =item C<Can't have two ATTR specifiers on one subroutine>
811 You just can't, okay?
812 Instead, put all the specifications together with commas between them
813 in a single C<ATTR(I<specification>)>.
815 =item C<Can't autotie a %s>
817 You can only declare autoties for types C<"SCALAR">, C<"ARRAY">, and
818 C<"HASH">. They're the only things (apart from typeglobs -- which are
819 not declarable) that Perl can tie.
821 =item C<Internal error: %s symbol went missing>
823 Something is rotten in the state of the program. An attributed
824 subroutine ceased to exist between the point it was declared and the point
825 at which its attribute handler(s) would have been called.
827 =item C<Won't be able to apply END handler>
829 You have defined an END handler for an attribute that is being applied
830 to a lexical variable. Since the variable may not be available during END
837 Damian Conway (damian@conway.org)
841 There are undoubtedly serious bugs lurking somewhere in code this funky :-)
842 Bug reports and other feedback are most welcome.
846 Copyright (c) 2001, Damian Conway. All Rights Reserved.
847 This module is free software. It may be used, redistributed
848 and/or modified under the same terms as Perl itself.