Will also initialize the %FIELDS hash if one of the base classes has
it. Multiple inheritance of %FIELDS is not supported. The 'base'
-pragma will croak if multiple base classes has a %FIELDS hash. See
+pragma will croak if multiple base classes have a %FIELDS hash. See
L<fields> for a description of this feature.
When strict 'vars' is in scope I<base> also let 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. 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, <base> will
+define $VERSION in the base package, setting it to the string
+C<-1, set by base.pm>.
+
+=head1 HISTORY
+
This module was introduced with Perl 5.004_04.
=head1 SEE ALSO
package base;
+use 5.006_001;
+our $VERSION = "1.03";
+
sub import {
my $class = shift;
my $fields_base;
+ my $pkg = caller(0);
foreach my $base (@_) {
- unless (defined %{"$base\::"}) {
+ next if $pkg->isa($base);
+ my $vglob;
+ if ($vglob = ${"$base\::"}{VERSION} and *$vglob{SCALAR}) {
+ $$vglob = "-1, set by base.pm" unless defined $$vglob;
+ } else {
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 (defined %{"$base\::"}) {
+ unless (%{"$base\::"}) {
require Carp;
Carp::croak("Base class package \"$base\" is empty.\n",
"\t(Perhaps you need to 'use' the module ",
"which defines that package first.)");
}
+ ${"$base\::VERSION"} = "-1, set by base.pm" unless defined ${"$base\::VERSION"};
}
+ push @{"$pkg\::ISA"}, $base;
# A simple test like (defined %{"$base\::FIELDS"}) will
# sometimes produce typo warnings because it would create
}
}
}
- my $pkg = caller(0);
- push @{"$pkg\::ISA"}, @_;
if ($fields_base) {
require fields;
fields::inherit($pkg, $fields_base);