X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbase.pm;h=be4c667e674f60f31a3a5d4d0f98a1dfb1fe413c;hb=d81018543234fe5f8d429eb7048c0b50792ea031;hp=4c4fb8b86bfac5ba906079e9d9c0591ea5c1dffa;hpb=9b599b2a63d2324ddacddd9710c41b795a95070d;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/base.pm b/lib/base.pm index 4c4fb8b..be4c667 100644 --- a/lib/base.pm +++ b/lib/base.pm @@ -1,52 +1,261 @@ +package base; + +use strict 'vars'; +use vars qw($VERSION); +$VERSION = '2.13'; + +# 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( ($fglob && 'GLOB' eq ref($fglob) && *$fglob{HASH}) ? 1 : 0 ); +} + +sub has_version { + my($base) = shift; + my $vglob = ${$base.'::'}{VERSION}; + return( ($vglob && *$vglob{SCALAR}) ? 1 : 0 ); +} + +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]}; +} + +if ($] < 5.009) { + *get_fields = sub { + # Shut up a possible typo warning. + () = \%{$_[0].'::FIELDS'}; + my $f = \%{$_[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 $class = shift; + + return SUCCESS unless @_; + + # List of base classes from which we will inherit %FIELDS. + my $fields_base; + + my $inheritor = caller(0); + my @isa_classes; + + my @bases; + foreach my $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'}; + } + else { + 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 $" = " "; + Carp::croak(<[0] = @$battr; + + if( keys %$dfields ) { + warn <<"END"; +$derived is inheriting from $base but already has its own fields! +This will cause problems. Be sure you use base BEFORE declaring fields. +END + + } + + # Iterate through the base's fields adding all the non-private + # ones to the derived class. Hang on to the original attribute + # (Public, Private, etc...) and add Inherited. + # This is all too complicated to do efficiently with add_fields(). + while (my($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] = PRIVATE | INHERITED; + } + else { + $dattr->[$v] = INHERITED | $battr->[$v]; + $dfields->{$k} = $v; + } + } + + foreach my $idx (1..$#{$battr}) { + next if defined $dattr->[$idx]; + $dattr->[$idx] = $battr->[$idx] & INHERITED; + } +} + + +1; + +__END__ + =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 package Baz; - use base qw(Foo Bar); =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); + require Foo; + require Bar; + push @ISA, qw(Foo Bar); } -This module was introduced with Perl 5.004_04. +C employs some heuristics to determine if a module has already been +loaded, if it has it doesn't try again. If C tries to C 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: -=head1 BUGS + package Foo; + sub exclaim { "I can have such a thing?!" } + + package Bar; + use base "Foo"; -Needs proper documentation! +If $VERSION is not detected even after loading it, will define $VERSION +in the base package, setting it to the string C<-1, set by base.pm>. -=cut +C will also initialize the fields if one of the base classes has it. +Multiple inheritance of fields is B supported, if two or more base classes +each have inheritable fields the 'base' pragma will croak. See L, +L and L for a description of this feature. -package base; +The base class' C method is B called. -sub import { - my $class = shift; - foreach my $base (@_) { - unless (defined %{"$base\::"}) { - 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 %{"$base\::"}) { - require Carp; - Carp::croak("Base class package \"$base\" is empty.\n", - "\t(Perhaps you need to 'use' the module ", - "which defines that package first.)"); - } - } - } - - push @{caller(0) . '::ISA'}, @_; -} +=head1 DIAGNOSTICS -1; +=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 implementation, you must use +base I you declare any of your own fields. + + +=head1 SEE ALSO + +L + +=cut