use strict 'vars';
use vars qw($VERSION);
-$VERSION = '2.03';
+$VERSION = '2.14';
+$VERSION = eval $VERSION;
# constant.pm is slow
sub SUCCESS () { 1 }
sub has_fields {
my($base) = shift;
my $fglob = ${"$base\::"}{FIELDS};
- return( ($fglob && *$fglob{HASH}) ? 1 : 0 );
+ return( ($fglob && 'GLOB' eq ref($fglob) && *$fglob{HASH}) ? 1 : 0 );
}
sub has_version {
return $Fattr->{$_[0]};
}
-sub get_fields {
- # Shut up a possible typo warning.
- () = \%{$_[0].'::FIELDS'};
+if ($] < 5.009) {
+ *get_fields = sub {
+ # Shut up a possible typo warning.
+ () = \%{$_[0].'::FIELDS'};
+ my $f = \%{$_[0].'::FIELDS'};
- return \%{$_[0].'::FIELDS'};
+ # should be centralized in fields? perhaps
+ # fields::mk_FIELDS_be_OK. Peh. As long as %{ $package . '::FIELDS' }
+ # is used here anyway, it doesn't matter.
+ bless $f, 'pseudohash' if (ref($f) ne 'pseudohash');
+
+ return $f;
+ }
+}
+else {
+ *get_fields = sub {
+ # Shut up a possible typo warning.
+ () = \%{$_[0].'::FIELDS'};
+ return \%{$_[0].'::FIELDS'};
+ }
}
sub import {
my $fields_base;
my $inheritor = caller(0);
+ my @isa_classes;
+ my @bases;
foreach my $base (@_) {
- next if $inheritor->isa($base);
+ if ( $inheritor eq $base ) {
+ warn "Class '$inheritor' tried to inherit from itself\n";
+ }
+
+ next if grep $_->isa($base), ($inheritor, @bases);
if (has_version($base)) {
- ${$base.'::VERSION'} = '-1, set by base.pm'
- unless defined ${$base.'::VERSION'};
+ ${$base.'::VERSION'} = '-1, set by base.pm'
+ unless defined ${$base.'::VERSION'};
}
else {
- local $SIG{__DIE__} = 'IGNORE';
- eval "require $base";
- # Only ignore "Can't locate" errors from our eval require.
- # Other fatal errors (syntax etc) must be reported.
- die if $@ && $@ !~ /^Can't locate .*? at \(eval /;
- unless (%{"$base\::"}) {
- require Carp;
- Carp::croak(<<ERROR);
+ my $sigdie;
+ {
+ local $SIG{__DIE__};
+ eval "require $base";
+ # Only ignore "Can't locate" errors from our eval require.
+ # Other fatal errors (syntax etc) must be reported.
+ die if $@ && $@ !~ /^Can't locate .*? at \(eval /;
+ unless (%{"$base\::"}) {
+ require Carp;
+ local $" = " ";
+ Carp::croak(<<ERROR);
Base class package "$base" is empty.
- (Perhaps you need to 'use' the module which defines that package first.)
+ (Perhaps you need to 'use' the module which defines that package first,
+ or make that module available in \@INC (\@INC contains: @INC).
ERROR
-
+ }
+ $sigdie = $SIG{__DIE__} || undef;
}
+ # Make sure a global $SIG{__DIE__} makes it out of the localization.
+ $SIG{__DIE__} = $sigdie if defined $sigdie;
${$base.'::VERSION'} = "-1, set by base.pm"
unless defined ${$base.'::VERSION'};
}
- push @{"$inheritor\::ISA"}, $base;
+ push @bases, $base;
if ( has_fields($base) || has_attr($base) ) {
- # No multiple fields inheritence *suck*
- if ($fields_base) {
- require Carp;
- Carp::croak("Can't multiply inherit %FIELDS");
- } else {
- $fields_base = $base;
- }
+ # No multiple fields inheritance *suck*
+ if ($fields_base) {
+ require Carp;
+ Carp::croak("Can't multiply inherit fields");
+ } else {
+ $fields_base = $base;
+ }
}
}
+ # Save this until the end so it's all or nothing if the above loop croaks.
+ push @{"$inheritor\::ISA"}, @isa_classes;
+
+ push @{"$inheritor\::ISA"}, @bases;
if( defined $fields_base ) {
inherit_fields($inheritor, $fields_base);
$dattr->[0] = @$battr;
if( keys %$dfields ) {
- warn "$derived is inheriting from $base but already has its own ".
- "fields!\n".
- "This will cause problems with pseudo-hashes.\n".
- "Be sure you use base BEFORE declaring fields\n";
+ warn <<"END";
+$derived is inheriting from $base but already has its own fields!
+This will cause problems. Be sure you use base BEFORE declaring fields.
+END
+
}
# Iterate through the base's fields adding all the non-private
# This is all too complicated to do efficiently with add_fields().
while (my($k,$v) = each %$bfields) {
my $fno;
- if ($fno = $dfields->{$k} and $fno != $v) {
- require Carp;
- Carp::croak ("Inherited %FIELDS can't override existing %FIELDS");
- }
+ if ($fno = $dfields->{$k} and $fno != $v) {
+ require Carp;
+ Carp::croak ("Inherited fields can't override existing fields");
+ }
if( $battr->[$v] & PRIVATE ) {
$dattr->[$v] = PRIVATE | INHERITED;
}
}
- unless( keys %$bfields ) {
- foreach my $idx (1..$#{$battr}) {
- $dattr->[$idx] = $battr->[$idx] & INHERITED;
- }
+ foreach my $idx (1..$#{$battr}) {
+ next if defined $dattr->[$idx];
+ $dattr->[$idx] = $battr->[$idx] & INHERITED;
}
}
=head1 NAME
-base - Establish IS-A relationship with base class at compile time
+base - Establish an ISA relationship with base classes at compile time
=head1 SYNOPSIS
=head1 DESCRIPTION
-Roughly similar in effect to
+Unless you are using the C<fields> pragma, consider this module discouraged
+in favor of the lighter-weight C<parent>.
+
+Allows you to both load one or more modules, while setting up inheritance from
+those modules at the same time. Roughly similar in effect to
+ package Baz;
BEGIN {
require Foo;
require Bar;
push @ISA, qw(Foo Bar);
}
-Will also initialize the fields if one of the base classes has it.
-Multiple Inheritence of fields is B<NOT> supported, if two or more
-base classes each have inheritable fields the 'base' pragma will
-croak. See L<fields>, L<public> and L<protected> for a description of
-this feature.
+C<base> employs some heuristics to determine if a module has already been
+loaded, if it has it doesn't try again. If C<base> tries to C<require> the
+module it will not die if it cannot find the module's file, but will die on any
+other error. After all this, should your base class be empty, containing no
+symbols, it will die. This is useful for inheriting from classes in the same
+file as yourself, like so:
+
+ package Foo;
+ sub exclaim { "I can have such a thing?!" }
+
+ package Bar;
+ use base "Foo";
+
+If $VERSION is not detected even after loading it, <base> will define $VERSION
+in the base package, setting it to the string C<-1, set by base.pm>.
+
+C<base> will also initialize the fields if one of the base classes has it.
+Multiple inheritance of fields is B<NOT> supported, if two or more base classes
+each have inheritable fields the 'base' pragma will croak. See L<fields>,
+L<public> and L<protected> for a description of this feature.
+
+The base class' C<import> method is B<not> called.
-When strict 'vars' is in scope, I<base> also lets you assign to @ISA
-without having to declare @ISA with the 'vars' pragma first.
-If any of the base classes are not loaded yet, I<base> silently
-C<require>s them (but it won't call the C<import> method). Whether to
-C<require> a base class package is determined by the absence of a global
-$VERSION in the base package. If $VERSION is not detected even after
-loading it, I<base> will define $VERSION in the base package, setting it to
-the string C<-1, set by base.pm>.
+=head1 DIAGNOSTICS
+=over 4
+
+=item Base class package "%s" is empty.
+
+base.pm was unable to require the base package, because it was not
+found in your path.
+
+=item Class 'Foo' tried to inherit from itself
+
+Attempting to inherit from yourself generates a warning.
+
+ use Foo;
+ use base 'Foo';
+
+=back
=head1 HISTORY
This module was introduced with Perl 5.004_04.
-
=head1 CAVEATS
-Due to the limitations of the pseudo-hash implementation, you must use
+Due to the limitations of the implementation, you must use
base I<before> you declare any of your own fields.
https://perl5.git.perl.org / perl5.git / blobdiff