Upgrade to base.pm 2.0.

(Rename the tests around a bit to be more 8.3-friendly.)

p4raw-id: //depot/perl@20960

1 files changed, 183 insertions, 57 deletions

diff --git a/lib/base.pm b/lib/base.pm
index 9b343987f9..e0cc4819ea 100644
--- a/lib/base.pm
+++ b/lib/base.pm
@@ -1,3 +1,171 @@
+package base;
+
+use vars qw($VERSION);
+$VERSION = '2.0';
+
+# constant.pm is slow
+sub SUCCESS () { 1 }
+
+sub PUBLIC     () { 2**0  }
+sub PRIVATE    () { 2**1  }
+sub INHERITED  () { 2**2  }
+sub PROTECTED  () { 2**3  }
+
+
+my $Fattr = \%fields::attr;
+
+sub has_fields {
+    my($base) = shift;
+    my $fglob = ${"$base\::"}{FIELDS};
+    return $fglob && *$fglob{HASH};
+}
+
+sub has_version {
+    my($base) = shift;
+    my $vglob = ${$base.'::'}{VERSION};
+    return $vglob && *$vglob{SCALAR};
+}
+
+sub has_attr {
+    my($proto) = shift;
+    my($class) = ref $proto || $proto;
+    return exists $Fattr->{$class};
+}
+
+sub get_attr {
+    $Fattr->{$_[0]} = [1] unless $Fattr->{$_[0]};
+    return $Fattr->{$_[0]};
+}
+
+sub get_fields {
+    # Shut up a possible typo warning.
+    () = \%{$_[0].'::FIELDS'};
+
+    return \%{$_[0].'::FIELDS'};
+}
+
+sub show_fields {
+    my($base, $mask) = @_;
+    my $fields = \%{$base.'::FIELDS'};
+    return grep { ($Fattr->{$base}[$fields->{$_}] & $mask) == $mask} 
+                keys %$fields;
+}
+
+
+sub import {
+    my $class = shift;
+
+    return SUCCESS unless @_;
+
+    # List of base classes from which we will inherit %FIELDS.
+    my $fields_base;
+
+    my $inheritor = caller(0);
+
+    foreach my $base (@_) {
+        next if $inheritor->isa($base);
+
+        if (has_version($base)) {
+	    ${$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 (%{"$base\::"}) {
+                require Carp;
+                Carp::croak(<<ERROR);
+Base class package "$base" is empty.
+    (Perhaps you need to 'use' the module which defines that package first.)
+ERROR
+
+            }
+            ${$base.'::VERSION'} = "-1, set by base.pm"
+              unless defined ${$base.'::VERSION'};
+        }
+        push @{"$inheritor\::ISA"}, $base;
+
+        # A simple test like (defined %{"$base\::FIELDS"}) will
+        # sometimes produce typo warnings because it would create
+        # the hash if it was not present before.
+        #
+        # We don't just check to see if the base in question has %FIELDS
+        # defined, we also check to see if it has -inheritable- fields.
+        # Its perfectly alright to inherit from multiple classes that have 
+        # %FIELDS as long as only one of them has fields to give.
+        if ( has_fields($base) || has_attr($base) ) {
+	    # Check to see if there are fields to be inherited.
+	    if ( show_fields($base, PUBLIC) or
+                 show_fields($base, PROTECTED) ) {
+		# No multiple fields inheritence *suck*
+		if ($fields_base) {
+		    require Carp;
+		    Carp::croak("Can't multiply inherit %FIELDS");
+		} else {
+		    $fields_base = $base;
+		}
+	    }
+        }
+    }
+
+    if( defined $fields_base ) {
+        inherit_fields($inheritor, $fields_base);
+    }
+}
+
+
+sub inherit_fields {
+    my($derived, $base) = @_;
+
+    return SUCCESS unless $base;
+
+    my $battr = get_attr($base);
+    my $dattr = get_attr($derived);
+    my $dfields = get_fields($derived);
+    my $bfields = get_fields($base);
+
+    $dattr->[0] = @$battr;
+
+    if( keys %$dfields ) {
+        warn "$derived is inheriting from $base but already has its own ".
+             "fields!\n".
+             "This will cause problems with pseudo-hashes.\n".
+             "Be sure you use base BEFORE declaring fields\n";
+    }
+
+    # Iterate through the base's fields adding all the non-private
+    # ones to the derived class.  Hang on to the original attribute
+    # (Public, Private, etc...) and add Inherited.
+    # This is all too complicated to do efficiently with add_fields().
+    while (my($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( $battr->[$v] & PRIVATE ) {
+            $dattr->[$v] = undef;
+        }
+        else {
+            $dattr->[$v] = INHERITED | $battr->[$v];
+
+            # Derived fields must be kept in the same position as the
+            # base in order to make "static" typing work with psuedo-hashes.
+            # Alas, this kills multiple field inheritance.
+            $dfields->{$k} = $v;
+        }
+    }
+}
+
+
+1;
+
+__END__
+
 =head1 NAME
 
 base - Establish IS-A relationship with base class at compile time
@@ -12,15 +180,16 @@ base - Establish IS-A relationship with base class at compile time
 Roughly similar in effect to
 
     BEGIN {
-	require Foo;
-	require Bar;
-	push @ISA, qw(Foo Bar);
+        require Foo;
+        require Bar;
+        push @ISA, qw(Foo Bar);
     }
 
-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 have a %FIELDS hash.  See
-L<fields> for a description of this feature.
+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.
 
 When strict 'vars' is in scope, I<base> also lets you assign to @ISA
 without having to declare @ISA with the 'vars' pragma first.
@@ -32,63 +201,20 @@ $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 HISTORY
 
 This module was introduced with Perl 5.004_04.
 
-=head1 SEE ALSO
-
-L<fields>
 
-=cut
+=head1 CAVEATS
 
-package base;
+Due to the limitations of the pseudo-hash implementation, you must use
+base I<before> you declare any of your own fields.
 
-use 5.006_001;
-our $VERSION = "1.04";
 
-sub import {
-    my $class = shift;
-    my $fields_base;
-    my $pkg = caller(0);
+=head1 SEE ALSO
 
-    foreach my $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 (%{"$base\::"}) {
-		require Carp;
-		Carp::croak("Base class package \"$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
-	# the hash if it was not present before.
-	my $fglob;
-	if ($fglob = ${"$base\::"}{"FIELDS"} and *$fglob{HASH}) {
-	    if ($fields_base) {
-		require Carp;
-		Carp::croak("Can't multiply inherit %FIELDS");
-	    } else {
-		$fields_base = $base;
-	    }
-	}
-    }
-    if ($fields_base) {
-	require fields;
-	fields::inherit($pkg, $fields_base);
-    }
-}
+L<fields>
 
-1;
+=cut