+++ /dev/null
-package Attribute::Handlers;
-use 5.006;
-use Carp;
-use warnings;
-$VERSION = '0.76';
-# $DB::single=1;
-
-my %symcache;
-sub findsym {
- my ($pkg, $ref, $type) = @_;
- return $symcache{$pkg,$ref} if $symcache{$pkg,$ref};
- $type ||= ref($ref);
- my $found;
- foreach my $sym ( values %{$pkg."::"} ) {
- return $symcache{$pkg,$ref} = \$sym
- if *{$sym}{$type} && *{$sym}{$type} == $ref;
- }
-}
-
-my %validtype = (
- VAR => [qw[SCALAR ARRAY HASH]],
- ANY => [qw[SCALAR ARRAY HASH CODE]],
- "" => [qw[SCALAR ARRAY HASH CODE]],
- SCALAR => [qw[SCALAR]],
- ARRAY => [qw[ARRAY]],
- HASH => [qw[HASH]],
- CODE => [qw[CODE]],
-);
-my %lastattr;
-my @declarations;
-my %raw;
-my %phase;
-my %sigil = (SCALAR=>'$', ARRAY=>'@', HASH=>'%');
-
-sub _usage_AH_ {
- croak "Usage: use $_[0] autotie => {AttrName => TieClassName,...}";
-}
-
-my $qual_id = qr/^[_a-z]\w*(::[_a-z]\w*)*$/i;
-
-sub import {
- my $class = shift @_;
- return unless $class eq "Attribute::Handlers";
- while (@_) {
- my $cmd = shift;
- if ($cmd =~ /^autotie((?:ref)?)$/) {
- my $tiedata = ($1 ? '$ref, ' : '') . '@$data';
- my $mapping = shift;
- _usage_AH_ $class unless ref($mapping) eq 'HASH';
- while (my($attr, $tieclass) = each %$mapping) {
- $tieclass =~ s/^([_a-z]\w*(::[_a-z]\w*)*)(.*)/$1/is;
- my $args = $3||'()';
- _usage_AH_ $class unless $attr =~ $qual_id
- && $tieclass =~ $qual_id
- && eval "use base $tieclass; 1";
- if ($tieclass->isa('Exporter')) {
- local $Exporter::ExportLevel = 2;
- $tieclass->import(eval $args);
- }
- $attr =~ s/__CALLER__/caller(1)/e;
- $attr = caller()."::".$attr unless $attr =~ /::/;
- eval qq{
- sub $attr : ATTR(VAR) {
- my (\$ref, \$data) = \@_[2,4];
- my \$was_arrayref = ref \$data eq 'ARRAY';
- \$data = [ \$data ] unless \$was_arrayref;
- my \$type = ref(\$ref)||"value (".(\$ref||"<undef>").")";
- (\$type eq 'SCALAR')? tie \$\$ref,'$tieclass',$tiedata
- :(\$type eq 'ARRAY') ? tie \@\$ref,'$tieclass',$tiedata
- :(\$type eq 'HASH') ? tie \%\$ref,'$tieclass',$tiedata
- : die "Can't autotie a \$type\n"
- } 1
- } or die "Internal error: $@";
- }
- }
- else {
- croak "Can't understand $_";
- }
- }
-}
-sub _resolve_lastattr {
- return unless $lastattr{ref};
- my $sym = findsym @lastattr{'pkg','ref'}
- or die "Internal error: $lastattr{pkg} symbol went missing";
- my $name = *{$sym}{NAME};
- warn "Declaration of $name attribute in package $lastattr{pkg} may clash with future reserved word\n"
- if $^W and $name !~ /[A-Z]/;
- foreach ( @{$validtype{$lastattr{type}}} ) {
- *{"$lastattr{pkg}::_ATTR_${_}_${name}"} = $lastattr{ref};
- }
- %lastattr = ();
-}
-
-sub AUTOLOAD {
- my ($class) = $AUTOLOAD =~ m/(.*)::/g;
- $AUTOLOAD =~ m/_ATTR_(.*?)_(.*)/ or
- croak "Can't locate class method '$AUTOLOAD' via package '$class'";
- croak "Attribute handler '$3' doesn't handle $2 attributes";
-}
-
-sub DESTROY {}
-
-my $builtin = qr/lvalue|method|locked/;
-
-sub _gen_handler_AH_() {
- return sub {
- _resolve_lastattr;
- my ($pkg, $ref, @attrs) = @_;
- foreach (@attrs) {
- my ($attr, $data) = /^([a-z_]\w*)(?:[(](.*)[)])?$/is or next;
- if ($attr eq 'ATTR') {
- $data ||= "ANY";
- $raw{$ref} = $data =~ s/\s*,?\s*RAWDATA\s*,?\s*//;
- $phase{$ref}{BEGIN} = 1
- if $data =~ s/\s*,?\s*(BEGIN)\s*,?\s*//;
- $phase{$ref}{INIT} = 1
- if $data =~ s/\s*,?\s*(INIT)\s*,?\s*//;
- $phase{$ref}{END} = 1
- if $data =~ s/\s*,?\s*(END)\s*,?\s*//;
- $phase{$ref}{CHECK} = 1
- if $data =~ s/\s*,?\s*(CHECK)\s*,?\s*//
- || ! keys %{$phase{$ref}};
- croak "Can't have two ATTR specifiers on one subroutine"
- if keys %lastattr;
- croak "Bad attribute type: ATTR($data)"
- unless $validtype{$data};
- %lastattr=(pkg=>$pkg,ref=>$ref,type=>$data);
- }
- else {
- my $handler = $pkg->can($attr);
- next unless $handler;
- my $decl = [$pkg, $ref, $attr, $data,
- $raw{$handler}, $phase{$handler}];
- _apply_handler_AH_($decl,'BEGIN');
- push @declarations, $decl;
- }
- $_ = undef;
- }
- return grep {defined && !/$builtin/} @attrs;
- }
-}
-
-*{"MODIFY_${_}_ATTRIBUTES"} = _gen_handler_AH_ foreach @{$validtype{ANY}};
-push @UNIVERSAL::ISA, 'Attribute::Handlers'
- unless grep /^Attribute::Handlers$/, @UNIVERSAL::ISA;
-
-sub _apply_handler_AH_ {
- my ($declaration, $phase) = @_;
- my ($pkg, $ref, $attr, $data, $raw, $handlerphase) = @$declaration;
- return unless $handlerphase->{$phase};
- # print STDERR "Handling $attr on $ref in $phase with [$data]\n";
- my $type = ref $ref;
- my $handler = "_ATTR_${type}_${attr}";
- my $sym = findsym($pkg, $ref);
- $sym ||= $type eq 'CODE' ? 'ANON' : 'LEXICAL';
- no warnings;
- my $evaled = !$raw && eval("package $pkg; no warnings;
- local \$SIG{__WARN__}=sub{die}; [$data]");
- $data = ($evaled && $data =~ /^\s*\[/) ? [$evaled]
- : ($evaled) ? $evaled
- : [$data];
- $pkg->$handler($sym,
- (ref $sym eq 'GLOB' ? *{$sym}{ref $ref}||$ref : $ref),
- $attr,
- (@$data>1? $data : $data->[0]),
- $phase,
- );
- return 1;
-}
-
-CHECK {
- _resolve_lastattr;
- _apply_handler_AH_($_,'CHECK') foreach @declarations;
-}
-
-INIT { _apply_handler_AH_($_,'INIT') foreach @declarations }
-
-END { _apply_handler_AH_($_,'END') foreach @declarations }
-
-1;
-__END__
-
-=head1 NAME
-
-Attribute::Handlers - Simpler definition of attribute handlers
-
-=head1 VERSION
-
-This document describes version 0.76 of Attribute::Handlers,
-released November 15, 2001.
-
-=head1 SYNOPSIS
-
- package MyClass;
- require v5.6.0;
- use Attribute::Handlers;
- no warnings 'redefine';
-
-
- sub Good : ATTR(SCALAR) {
- my ($package, $symbol, $referent, $attr, $data) = @_;
-
- # Invoked for any scalar variable with a :Good attribute,
- # provided the variable was declared in MyClass (or
- # a derived class) or typed to MyClass.
-
- # Do whatever to $referent here (executed in CHECK phase).
- ...
- }
-
- sub Bad : ATTR(SCALAR) {
- # Invoked for any scalar variable with a :Bad attribute,
- # provided the variable was declared in MyClass (or
- # a derived class) or typed to MyClass.
- ...
- }
-
- sub Good : ATTR(ARRAY) {
- # Invoked for any array variable with a :Good attribute,
- # provided the variable was declared in MyClass (or
- # a derived class) or typed to MyClass.
- ...
- }
-
- sub Good : ATTR(HASH) {
- # Invoked for any hash variable with a :Good attribute,
- # provided the variable was declared in MyClass (or
- # a derived class) or typed to MyClass.
- ...
- }
-
- sub Ugly : ATTR(CODE) {
- # Invoked for any subroutine declared in MyClass (or a
- # derived class) with an :Ugly attribute.
- ...
- }
-
- sub Omni : ATTR {
- # Invoked for any scalar, array, hash, or subroutine
- # with an :Omni attribute, provided the variable or
- # subroutine was declared in MyClass (or a derived class)
- # or the variable was typed to MyClass.
- # Use ref($_[2]) to determine what kind of referent it was.
- ...
- }
-
-
- use Attribute::Handlers autotie => { Cycle => Tie::Cycle };
-
- my $next : Cycle(['A'..'Z']);
-
-
-=head1 DESCRIPTION
-
-This module, when inherited by a package, allows that package's class to
-define attribute handler subroutines for specific attributes. Variables
-and subroutines subsequently defined in that package, or in packages
-derived from that package may be given attributes with the same names as
-the attribute handler subroutines, which will then be called in one of
-the compilation phases (i.e. in a C<BEGIN>, C<CHECK>, C<INIT>, or C<END>
-block).
-
-To create a handler, define it as a subroutine with the same name as
-the desired attribute, and declare the subroutine itself with the
-attribute C<:ATTR>. For example:
-
- package LoudDecl;
- use Attribute::Handlers;
-
- sub Loud :ATTR {
- my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
- print STDERR
- ref($referent), " ",
- *{$symbol}{NAME}, " ",
- "($referent) ", "was just declared ",
- "and ascribed the ${attr} attribute ",
- "with data ($data)\n",
- "in phase $phase\n";
- }
-
-This creates a handler for the attribute C<:Loud> in the class LoudDecl.
-Thereafter, any subroutine declared with a C<:Loud> attribute in the class
-LoudDecl:
-
- package LoudDecl;
-
- sub foo: Loud {...}
-
-causes the above handler to be invoked, and passed:
-
-=over
-
-=item [0]
-
-the name of the package into which it was declared;
-
-=item [1]
-
-a reference to the symbol table entry (typeglob) containing the subroutine;
-
-=item [2]
-
-a reference to the subroutine;
-
-=item [3]
-
-the name of the attribute;
-
-=item [4]
-
-any data associated with that attribute;
-
-=item [5]
-
-the name of the phase in which the handler is being invoked.
-
-=back
-
-Likewise, declaring any variables with the C<:Loud> attribute within the
-package:
-
- package LoudDecl;
-
- my $foo :Loud;
- my @foo :Loud;
- my %foo :Loud;
-
-will cause the handler to be called with a similar argument list (except,
-of course, that C<$_[2]> will be a reference to the variable).
-
-The package name argument will typically be the name of the class into
-which the subroutine was declared, but it may also be the name of a derived
-class (since handlers are inherited).
-
-If a lexical variable is given an attribute, there is no symbol table to
-which it belongs, so the symbol table argument (C<$_[1]>) is set to the
-string C<'LEXICAL'> in that case. Likewise, ascribing an attribute to
-an anonymous subroutine results in a symbol table argument of C<'ANON'>.
-
-The data argument passes in the value (if any) associated with the
-attribute. For example, if C<&foo> had been declared:
-
- sub foo :Loud("turn it up to 11, man!") {...}
-
-then the string C<"turn it up to 11, man!"> would be passed as the
-last argument.
-
-Attribute::Handlers makes strenuous efforts to convert
-the data argument (C<$_[4]>) to a useable form before passing it to
-the handler (but see L<"Non-interpretive attribute handlers">).
-For example, all of these:
-
- sub foo :Loud(till=>ears=>are=>bleeding) {...}
- sub foo :Loud(['till','ears','are','bleeding']) {...}
- sub foo :Loud(qw/till ears are bleeding/) {...}
- sub foo :Loud(qw/my, ears, are, bleeding/) {...}
- sub foo :Loud(till,ears,are,bleeding) {...}
-
-causes it to pass C<['till','ears','are','bleeding']> as the handler's
-data argument. However, if the data can't be parsed as valid Perl, then
-it is passed as an uninterpreted string. For example:
-
- sub foo :Loud(my,ears,are,bleeding) {...}
- sub foo :Loud(qw/my ears are bleeding) {...}
-
-cause the strings C<'my,ears,are,bleeding'> and C<'qw/my ears are bleeding'>
-respectively to be passed as the data argument.
-
-If the attribute has only a single associated scalar data value, that value is
-passed as a scalar. If multiple values are associated, they are passed as an
-array reference. If no value is associated with the attribute, C<undef> is
-passed.
-
-
-=head2 Typed lexicals
-
-Regardless of the package in which it is declared, if a lexical variable is
-ascribed an attribute, the handler that is invoked is the one belonging to
-the package to which it is typed. For example, the following declarations:
-
- package OtherClass;
-
- my LoudDecl $loudobj : Loud;
- my LoudDecl @loudobjs : Loud;
- my LoudDecl %loudobjex : Loud;
-
-causes the LoudDecl::Loud handler to be invoked (even if OtherClass also
-defines a handler for C<:Loud> attributes).
-
-
-=head2 Type-specific attribute handlers
-
-If an attribute handler is declared and the C<:ATTR> specifier is
-given the name of a built-in type (C<SCALAR>, C<ARRAY>, C<HASH>, or C<CODE>),
-the handler is only applied to declarations of that type. For example,
-the following definition:
-
- package LoudDecl;
-
- sub RealLoud :ATTR(SCALAR) { print "Yeeeeow!" }
-
-creates an attribute handler that applies only to scalars:
-
-
- package Painful;
- use base LoudDecl;
-
- my $metal : RealLoud; # invokes &LoudDecl::RealLoud
- my @metal : RealLoud; # error: unknown attribute
- my %metal : RealLoud; # error: unknown attribute
- sub metal : RealLoud {...} # error: unknown attribute
-
-You can, of course, declare separate handlers for these types as well
-(but you'll need to specify C<no warnings 'redefine'> to do it quietly):
-
- package LoudDecl;
- use Attribute::Handlers;
- no warnings 'redefine';
-
- sub RealLoud :ATTR(SCALAR) { print "Yeeeeow!" }
- sub RealLoud :ATTR(ARRAY) { print "Urrrrrrrrrr!" }
- sub RealLoud :ATTR(HASH) { print "Arrrrrgggghhhhhh!" }
- sub RealLoud :ATTR(CODE) { croak "Real loud sub torpedoed" }
-
-You can also explicitly indicate that a single handler is meant to be
-used for all types of referents like so:
-
- package LoudDecl;
- use Attribute::Handlers;
-
- sub SeriousLoud :ATTR(ANY) { warn "Hearing loss imminent" }
-
-(I.e. C<ATTR(ANY)> is a synonym for C<:ATTR>).
-
-
-=head2 Non-interpretive attribute handlers
-
-Occasionally the strenuous efforts Attribute::Handlers makes to convert
-the data argument (C<$_[4]>) to a useable form before passing it to
-the handler get in the way.
-
-You can turn off that eagerness-to-help by declaring
-an attribute handler with the keyword C<RAWDATA>. For example:
-
- sub Raw : ATTR(RAWDATA) {...}
- sub Nekkid : ATTR(SCALAR,RAWDATA) {...}
- sub Au::Naturale : ATTR(RAWDATA,ANY) {...}
-
-Then the handler makes absolutely no attempt to interpret the data it
-receives and simply passes it as a string:
-
- my $power : Raw(1..100); # handlers receives "1..100"
-
-=head2 Phase-specific attribute handlers
-
-By default, attribute handlers are called at the end of the compilation
-phase (in a C<CHECK> block). This seems to be optimal in most cases because
-most things that can be defined are defined by that point but nothing has
-been executed.
-
-However, it is possible to set up attribute handlers that are called at
-other points in the program's compilation or execution, by explicitly
-stating the phase (or phases) in which you wish the attribute handler to
-be called. For example:
-
- sub Early :ATTR(SCALAR,BEGIN) {...}
- sub Normal :ATTR(SCALAR,CHECK) {...}
- sub Late :ATTR(SCALAR,INIT) {...}
- sub Final :ATTR(SCALAR,END) {...}
- sub Bookends :ATTR(SCALAR,BEGIN,END) {...}
-
-As the last example indicates, a handler may be set up to be (re)called in
-two or more phases. The phase name is passed as the handler's final argument.
-
-Note that attribute handlers that are scheduled for the C<BEGIN> phase
-are handled as soon as the attribute is detected (i.e. before any
-subsequently defined C<BEGIN> blocks are executed).
-
-
-=head2 Attributes as C<tie> interfaces
-
-Attributes make an excellent and intuitive interface through which to tie
-variables. For example:
-
- use Attribute::Handlers;
- use Tie::Cycle;
-
- sub UNIVERSAL::Cycle : ATTR(SCALAR) {
- my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
- $data = [ $data ] unless ref $data eq 'ARRAY';
- tie $$referent, 'Tie::Cycle', $data;
- }
-
- # and thereafter...
-
- package main;
-
- my $next : Cycle('A'..'Z'); # $next is now a tied variable
-
- while (<>) {
- print $next;
- }
-
-Note that, because the C<Cycle> attribute receives its arguments in the
-C<$data> variable, if the attribute is given a list of arguments, C<$data>
-will consist of a single array reference; otherwise, it will consist of the
-single argument directly. Since Tie::Cycle requires its cycling values to
-be passed as an array reference, this means that we need to wrap
-non-array-reference arguments in an array constructor:
-
- $data = [ $data ] unless ref $data eq 'ARRAY';
-
-Typically, however, things are the other way around: the tieable class expects
-its arguments as a flattened list, so the attribute looks like:
-
- sub UNIVERSAL::Cycle : ATTR(SCALAR) {
- my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
- my @data = ref $data eq 'ARRAY' ? @$data : $data;
- tie $$referent, 'Tie::Whatever', @data;
- }
-
-
-This software pattern is so widely applicable that Attribute::Handlers
-provides a way to automate it: specifying C<'autotie'> in the
-C<use Attribute::Handlers> statement. So, the cycling example,
-could also be written:
-
- use Attribute::Handlers autotie => { Cycle => 'Tie::Cycle' };
-
- # and thereafter...
-
- package main;
-
- my $next : Cycle(['A'..'Z']); # $next is now a tied variable
-
- while (<>) {
- print $next;
-
-Note that we now have to pass the cycling values as an array reference,
-since the C<autotie> mechanism passes C<tie> a list of arguments as a list
-(as in the Tie::Whatever example), I<not> as an array reference (as in
-the original Tie::Cycle example at the start of this section).
-
-The argument after C<'autotie'> is a reference to a hash in which each key is
-the name of an attribute to be created, and each value is the class to which
-variables ascribed that attribute should be tied.
-
-Note that there is no longer any need to import the Tie::Cycle module --
-Attribute::Handlers takes care of that automagically. You can even pass
-arguments to the module's C<import> subroutine, by appending them to the
-class name. For example:
-
- use Attribute::Handlers
- autotie => { Dir => 'Tie::Dir qw(DIR_UNLINK)' };
-
-If the attribute name is unqualified, the attribute is installed in the
-current package. Otherwise it is installed in the qualifier's package:
-
- package Here;
-
- use Attribute::Handlers autotie => {
- Other::Good => Tie::SecureHash, # tie attr installed in Other::
- Bad => Tie::Taxes, # tie attr installed in Here::
- UNIVERSAL::Ugly => Software::Patent # tie attr installed everywhere
- };
-
-Autoties are most commonly used in the module to which they actually tie,
-and need to export their attributes to any module that calls them. To
-facilitiate this, Attribute::Handlers recognizes a special "pseudo-class" --
-C<__CALLER__>, which may be specified as the qualifier of an attribute:
-
- package Tie::Me::Kangaroo:Down::Sport;
-
- use Attribute::Handlers autotie => { __CALLER__::Roo => __PACKAGE__ };
-
-This causes Attribute::Handlers to define the C<Roo> attribute in the package
-that imports the Tie::Me::Kangaroo:Down::Sport module.
-
-=head3 Passing the tied object to C<tie>
-
-Occasionally it is important to pass a reference to the object being tied
-to the TIESCALAR, TIEHASH, etc. that ties it.
-
-The C<autotie> mechanism supports this too. The following code:
-
- use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
- my $var : Selfish(@args);
-
-has the same effect as:
-
- tie my $var, 'Tie::Selfish', @args;
-
-But when C<"autotieref"> is used instead of C<"autotie">:
-
- use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
- my $var : Selfish(@args);
-
-the effect is to pass the C<tie> call an extra reference to the variable
-being tied:
-
- tie my $var, 'Tie::Selfish', \$var, @args;
-
-
-
-=head1 EXAMPLES
-
-If the class shown in L<SYNOPSIS> were placed in the MyClass.pm
-module, then the following code:
-
- package main;
- use MyClass;
-
- my MyClass $slr :Good :Bad(1**1-1) :Omni(-vorous);
-
- package SomeOtherClass;
- use base MyClass;
-
- sub tent { 'acle' }
-
- sub fn :Ugly(sister) :Omni('po',tent()) {...}
- my @arr :Good :Omni(s/cie/nt/);
- my %hsh :Good(q/bye) :Omni(q/bus/);
-
-
-would cause the following handlers to be invoked:
-
- # my MyClass $slr :Good :Bad(1**1-1) :Omni(-vorous);
-
- MyClass::Good:ATTR(SCALAR)( 'MyClass', # class
- 'LEXICAL', # no typeglob
- \$slr, # referent
- 'Good', # attr name
- undef # no attr data
- 'CHECK', # compiler phase
- );
-
- MyClass::Bad:ATTR(SCALAR)( 'MyClass', # class
- 'LEXICAL', # no typeglob
- \$slr, # referent
- 'Bad', # attr name
- 0 # eval'd attr data
- 'CHECK', # compiler phase
- );
-
- MyClass::Omni:ATTR(SCALAR)( 'MyClass', # class
- 'LEXICAL', # no typeglob
- \$slr, # referent
- 'Omni', # attr name
- '-vorous' # eval'd attr data
- 'CHECK', # compiler phase
- );
-
-
- # sub fn :Ugly(sister) :Omni('po',tent()) {...}
-
- MyClass::UGLY:ATTR(CODE)( 'SomeOtherClass', # class
- \*SomeOtherClass::fn, # typeglob
- \&SomeOtherClass::fn, # referent
- 'Ugly', # attr name
- 'sister' # eval'd attr data
- 'CHECK', # compiler phase
- );
-
- MyClass::Omni:ATTR(CODE)( 'SomeOtherClass', # class
- \*SomeOtherClass::fn, # typeglob
- \&SomeOtherClass::fn, # referent
- 'Omni', # attr name
- ['po','acle'] # eval'd attr data
- 'CHECK', # compiler phase
- );
-
-
- # my @arr :Good :Omni(s/cie/nt/);
-
- MyClass::Good:ATTR(ARRAY)( 'SomeOtherClass', # class
- 'LEXICAL', # no typeglob
- \@arr, # referent
- 'Good', # attr name
- undef # no attr data
- 'CHECK', # compiler phase
- );
-
- MyClass::Omni:ATTR(ARRAY)( 'SomeOtherClass', # class
- 'LEXICAL', # no typeglob
- \@arr, # referent
- 'Omni', # attr name
- "" # eval'd attr data
- 'CHECK', # compiler phase
- );
-
-
- # my %hsh :Good(q/bye) :Omni(q/bus/);
-
- MyClass::Good:ATTR(HASH)( 'SomeOtherClass', # class
- 'LEXICAL', # no typeglob
- \%hsh, # referent
- 'Good', # attr name
- 'q/bye' # raw attr data
- 'CHECK', # compiler phase
- );
-
- MyClass::Omni:ATTR(HASH)( 'SomeOtherClass', # class
- 'LEXICAL', # no typeglob
- \%hsh, # referent
- 'Omni', # attr name
- 'bus' # eval'd attr data
- 'CHECK', # compiler phase
- );
-
-
-Installing handlers into UNIVERSAL, makes them...err..universal.
-For example:
-
- package Descriptions;
- use Attribute::Handlers;
-
- my %name;
- sub name { return $name{$_[2]}||*{$_[1]}{NAME} }
-
- sub UNIVERSAL::Name :ATTR {
- $name{$_[2]} = $_[4];
- }
-
- sub UNIVERSAL::Purpose :ATTR {
- print STDERR "Purpose of ", &name, " is $_[4]\n";
- }
-
- sub UNIVERSAL::Unit :ATTR {
- print STDERR &name, " measured in $_[4]\n";
- }
-
-Let's you write:
-
- use Descriptions;
-
- my $capacity : Name(capacity)
- : Purpose(to store max storage capacity for files)
- : Unit(Gb);
-
-
- package Other;
-
- sub foo : Purpose(to foo all data before barring it) { }
-
- # etc.
-
-
-=head1 DIAGNOSTICS
-
-=over
-
-=item C<Bad attribute type: ATTR(%s)>
-
-An attribute handler was specified with an C<:ATTR(I<ref_type>)>, but the
-type of referent it was defined to handle wasn't one of the five permitted:
-C<SCALAR>, C<ARRAY>, C<HASH>, C<CODE>, or C<ANY>.
-
-=item C<Attribute handler %s doesn't handle %s attributes>
-
-A handler for attributes of the specified name I<was> defined, but not
-for the specified type of declaration. Typically encountered whe trying
-to apply a C<VAR> attribute handler to a subroutine, or a C<SCALAR>
-attribute handler to some other type of variable.
-
-=item C<Declaration of %s attribute in package %s may clash with future reserved word>
-
-A handler for an attributes with an all-lowercase name was declared. An
-attribute with an all-lowercase name might have a meaning to Perl
-itself some day, even though most don't yet. Use a mixed-case attribute
-name, instead.
-
-=item C<Can't have two ATTR specifiers on one subroutine>
-
-You just can't, okay?
-Instead, put all the specifications together with commas between them
-in a single C<ATTR(I<specification>)>.
-
-=item C<Can't autotie a %s>
-
-You can only declare autoties for types C<"SCALAR">, C<"ARRAY">, and
-C<"HASH">. They're the only things (apart from typeglobs -- which are
-not declarable) that Perl can tie.
-
-=item C<Internal error: %s symbol went missing>
-
-Something is rotten in the state of the program. An attributed
-subroutine ceased to exist between the point it was declared and the point
-at which its attribute handler(s) would have been called.
-
-=back
-
-=head1 AUTHOR
-
-Damian Conway (damian@conway.org)
-
-=head1 BUGS
-
-There are undoubtedly serious bugs lurking somewhere in code this funky :-)
-Bug reports and other feedback are most welcome.
-
-=head1 COPYRIGHT
-
- Copyright (c) 2001, Damian Conway. All Rights Reserved.
- This module is free software. It may be used, redistributed
- and/or modified under the same terms as Perl itself.
projects / p5sagit/p5-mst-13.2.git / commitdiff