X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbase.pm;h=37f220f63a9641bc68eae51b062d49259587419a;hb=4afb7519d86e52b18cb15a8ff307f1cc0cfb8e0f;hp=3500cbfb89856e69aeb8d7601ae0a8351ffad153;hpb=f1192ceea6b2a126a4ff3254f91c2bc47c361c71;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/base.pm b/lib/base.pm
index 3500cbf..37f220f 100644
--- a/lib/base.pm
+++ b/lib/base.pm
@@ -19,12 +19,21 @@ Roughly similar in effect to
 
 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
@@ -35,23 +44,33 @@ L<fields>
 
 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
@@ -66,8 +85,6 @@ sub import {
 	    }
 	}
     }
-    my $pkg = caller(0);
-    push @{"$pkg\::ISA"}, @_;
     if ($fields_base) {
 	require fields;
 	fields::inherit($pkg, $fields_base);