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Diffstat (limited to 'Master/tlpkg/tlperl/lib/base.pm')
-rw-r--r-- | Master/tlpkg/tlperl/lib/base.pm | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/base.pm b/Master/tlpkg/tlperl/lib/base.pm new file mode 100644 index 00000000000..001914be4d3 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/base.pm @@ -0,0 +1,226 @@ +package base; + +use strict 'vars'; +use vars qw($VERSION); +$VERSION = '2.07'; + +# 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}) ? 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); + + 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__}; + 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"}, $base; + + if ( has_fields($base) || has_attr($base) ) { + # No multiple fields inheritence *suck* + if ($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 $base but already has its own ". + "fields!\n". + "This will cause problems.\n". + "Be sure you use base BEFORE declaring fields\n"; + } + + # Iterate through the base's fields adding all the non-private + # ones to the derived class. Hang on to the original attribute + # (Public, Private, etc...) and add Inherited. + # This is all too complicated to do efficiently with add_fields(). + while (my($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] = 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 classes at compile time + +=head1 SYNOPSIS + + package Baz; + use base qw(Foo Bar); + +=head1 DESCRIPTION + +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 +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. + +=head1 DIAGNOSTICS + +=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. + + +=head1 CAVEATS + +Due to the limitations of the implementation, you must use +base I<before> you declare any of your own fields. + + +=head1 SEE ALSO + +L<fields> + +=cut |