package base;
+use strict 'vars';
use vars qw($VERSION);
-$VERSION = '2.0';
+$VERSION = '2.08';
# constant.pm is slow
sub SUCCESS () { 1 }
sub has_fields {
my($base) = shift;
my $fglob = ${"$base\::"}{FIELDS};
- return $fglob && *$fglob{HASH};
+ return( ($fglob && *$fglob{HASH}) ? 1 : 0 );
}
sub has_version {
my($base) = shift;
my $vglob = ${$base.'::'}{VERSION};
- return $vglob && *$vglob{SCALAR};
+ return( ($vglob && *$vglob{SCALAR}) ? 1 : 0 );
}
sub has_attr {
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');
-sub show_fields {
- my($base, $mask) = @_;
- my $fields = \%{$base.'::FIELDS'};
- return grep { ($Fattr->{$base}[$fields->{$_}] & $mask) == $mask}
- keys %$fields;
+ return $f;
+ }
+}
+else {
+ *get_fields = sub {
+ # Shut up a possible typo warning.
+ () = \%{$_[0].'::FIELDS'};
+ return \%{$_[0].'::FIELDS'};
+ }
}
-
sub import {
my $class = shift;
my $inheritor = caller(0);
foreach my $base (@_) {
+ if ( $inheritor eq $base ) {
+ warn "Class '$inheritor' tried to inherit from itself\n";
+ }
+
next if $inheritor->isa($base);
if (has_version($base)) {
unless defined ${$base.'::VERSION'};
}
else {
- local $SIG{__DIE__} = 'IGNORE';
+ local $SIG{__DIE__};
eval "require $base";
# Only ignore "Can't locate" errors from our eval require.
# Other fatal errors (syntax etc) must be reported.
}
push @{"$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 = $base;
- }
+ # No multiple fields inheritance *suck*
+ if ($fields_base) {
+ require Carp;
+ Carp::croak("Can't multiply inherit %FIELDS");
+ } else {
+ $fields_base = $base;
}
}
}
if( keys %$dfields ) {
warn "$derived is inheriting from $base but already has its own ".
"fields!\n".
- "This will cause problems with pseudo-hashes.\n".
+ "This will cause problems.\n".
"Be sure you use base BEFORE declaring fields\n";
}
}
if( $battr->[$v] & PRIVATE ) {
- $dattr->[$v] = undef;
+ $dattr->[$v] = PRIVATE | INHERITED;
}
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;
}
}
+
+ 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 IS-A relationship with base classes at compile time
=head1 SYNOPSIS
=head1 DESCRIPTION
-Roughly similar in effect to
+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);
}
+If any of the listed modules are not loaded yet, I<base> silently attempts to
+C<require> them (and silently continues if the C<require> failed). Whether to
+C<require> a base class module is determined by the absence of a global variable
+$VERSION in the base package. If $VERSION is not detected even after loading
+it, <base> will define $VERSION in the base package, setting it to the string
+C<-1, set by base.pm>.
+
Will also initialize the fields if one of the base classes has it.
-Multiple Inheritence of fields is B<NOT> supported, if two or more
+Multiple inheritance of fields is B<NOT> supported, if two or more
base classes each have inheritable fields the 'base' pragma will
croak. See L<fields>, L<public> and L<protected> for a description of
this feature.
-When strict 'vars' is in scope, I<base> also lets you assign to @ISA
-without having to declare @ISA with the 'vars' pragma first.
+=head1 DIAGNOSTICS
-If any of the base classes are not loaded yet, I<base> silently
-C<require>s them (but it won't call the C<import> method). Whether to
-C<require> a base class package is determined by the absence of a global
-$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>.
+=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.
+
+=back
=head1 HISTORY
This module was introduced with Perl 5.004_04.
+Attempting to inherit from yourself generates a warning:
+
+ use Foo;
+ use base 'Foo';
+
+ # Class 'Foo' tried to inherit from itself
=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