JezK
Edit File: fields.pm
use 5.008; package fields; require 5.005; use strict; no strict 'refs'; unless( eval q{require warnings::register; warnings::register->import; 1} ) { *warnings::warnif = sub { require Carp; Carp::carp(@_); } } our %attr; our $VERSION = '2.24'; $VERSION =~ tr/_//d; # constant.pm is slow sub PUBLIC () { 2**0 } sub PRIVATE () { 2**1 } sub INHERITED () { 2**2 } sub PROTECTED () { 2**3 } # The %attr hash holds the attributes of the currently assigned fields # per class. The hash is indexed by class names and the hash value is # an array reference. The first element in the array is the lowest field # number not belonging to a base class. The remaining elements' indices # are the field numbers. The values are integer bit masks, or undef # in the case of base class private fields (which occupy a slot but are # otherwise irrelevant to the class). sub import { my $class = shift; return unless @_; my $package = caller(0); # avoid possible typo warnings %{"$package\::FIELDS"} = () unless %{"$package\::FIELDS"}; my $fields = \%{"$package\::FIELDS"}; my $fattr = ($attr{$package} ||= [1]); my $next = @$fattr; # Quiet pseudo-hash deprecation warning for uses of fields::new. bless \%{"$package\::FIELDS"}, 'pseudohash'; if ($next > $fattr->[0] and ($fields->{$_[0]} || 0) >= $fattr->[0]) { # There are already fields not belonging to base classes. # Looks like a possible module reload... $next = $fattr->[0]; } foreach my $f (@_) { my $fno = $fields->{$f}; # Allow the module to be reloaded so long as field positions # have not changed. if ($fno and $fno != $next) { require Carp; if ($fno < $fattr->[0]) { if ($] < 5.006001) { warn("Hides field '$f' in base class") if $^W; } else { warnings::warnif("Hides field '$f' in base class") ; } } else { Carp::croak("Field name '$f' already in use"); } } $fields->{$f} = $next; $fattr->[$next] = ($f =~ /^_/) ? PRIVATE : PUBLIC; $next += 1; } if (@$fattr > $next) { # Well, we gave them the benefit of the doubt by guessing the # module was reloaded, but they appear to be declaring fields # in more than one place. We can't be sure (without some extra # bookkeeping) that the rest of the fields will be declared or # have the same positions, so punt. require Carp; Carp::croak ("Reloaded module must declare all fields at once"); } } sub inherit { require base; goto &base::inherit_fields; } sub _dump # sometimes useful for debugging { for my $pkg (sort keys %attr) { print "\n$pkg"; if (@{"$pkg\::ISA"}) { print " (", join(", ", @{"$pkg\::ISA"}), ")"; } print "\n"; my $fields = \%{"$pkg\::FIELDS"}; for my $f (sort {$fields->{$a} <=> $fields->{$b}} keys %$fields) { my $no = $fields->{$f}; print " $no: $f"; my $fattr = $attr{$pkg}[$no]; if (defined $fattr) { my @a; push(@a, "public") if $fattr & PUBLIC; push(@a, "private") if $fattr & PRIVATE; push(@a, "inherited") if $fattr & INHERITED; print "\t(", join(", ", @a), ")"; } print "\n"; } } } if ($] < 5.009) { *new = sub { my $class = shift; $class = ref $class if ref $class; return bless [\%{$class . "::FIELDS"}], $class; } } else { *new = sub { my $class = shift; $class = ref $class if ref $class; require Hash::Util; my $self = bless {}, $class; # The lock_keys() prototype won't work since we require Hash::Util :( &Hash::Util::lock_keys(\%$self, _accessible_keys($class)); return $self; } } sub _accessible_keys { my ($class) = @_; return ( keys %{$class.'::FIELDS'}, map(_accessible_keys($_), @{$class.'::ISA'}), ); } sub phash { die "Pseudo-hashes have been removed from Perl" if $] >= 5.009; my $h; my $v; if (@_) { if (ref $_[0] eq 'ARRAY') { my $a = shift; @$h{@$a} = 1 .. @$a; if (@_) { $v = shift; unless (! @_ and ref $v eq 'ARRAY') { require Carp; Carp::croak ("Expected at most two array refs\n"); } } } else { if (@_ % 2) { require Carp; Carp::croak ("Odd number of elements initializing pseudo-hash\n"); } my $i = 0; @$h{grep ++$i % 2, @_} = 1 .. @_ / 2; $i = 0; $v = [grep $i++ % 2, @_]; } } else { $h = {}; $v = []; } [ $h, @$v ]; } 1; __END__