diff options
author | Todd C. Miller <millert@cvs.openbsd.org> | 2002-10-27 22:25:41 +0000 |
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committer | Todd C. Miller <millert@cvs.openbsd.org> | 2002-10-27 22:25:41 +0000 |
commit | d85c2f57f17d991a6ca78d3e1c9f3308a2bbb271 (patch) | |
tree | 8c9a359433cbb3488b0a848e99bd869c76295dfd /gnu/usr.bin/perl/lib/UNIVERSAL.pm | |
parent | 74cfb115ac810480c0000dc742b20383c1578bac (diff) |
Resolve conflicts, remove old files, merge local changes
Diffstat (limited to 'gnu/usr.bin/perl/lib/UNIVERSAL.pm')
-rw-r--r-- | gnu/usr.bin/perl/lib/UNIVERSAL.pm | 113 |
1 files changed, 65 insertions, 48 deletions
diff --git a/gnu/usr.bin/perl/lib/UNIVERSAL.pm b/gnu/usr.bin/perl/lib/UNIVERSAL.pm index f2f1fe9e7ad..92b4fcd352a 100644 --- a/gnu/usr.bin/perl/lib/UNIVERSAL.pm +++ b/gnu/usr.bin/perl/lib/UNIVERSAL.pm @@ -1,11 +1,16 @@ package UNIVERSAL; +our $VERSION = '1.00'; + # UNIVERSAL should not contain any extra subs/methods beyond those # that it exists to define. The use of Exporter below is a historical -# accident that should be fixed sometime. +# accident that can't be fixed without breaking code. Note that we +# *don't* set @ISA here, don't want all classes/objects inheriting from +# Exporter. It's bad enough that all classes have a import() method +# whenever UNIVERSAL.pm is loaded. require Exporter; *import = \&Exporter::import; -@EXPORT_OK = qw(isa can); +@EXPORT_OK = qw(isa can VERSION); 1; __END__ @@ -16,78 +21,90 @@ UNIVERSAL - base class for ALL classes (blessed references) =head1 SYNOPSIS - $io = $fd->isa("IO::Handle"); - $sub = $obj->can('print'); + $is_io = $fd->isa("IO::Handle"); + $is_io = Class->isa("IO::Handle"); + + $sub = $obj->can("print"); + $sub = Class->can("print"); - $yes = UNIVERSAL::isa($ref, "HASH"); + use UNIVERSAL qw( isa can VERSION ); + $yes = isa $ref, "HASH" ; + $sub = can $ref, "fandango" ; + $ver = VERSION $obj ; =head1 DESCRIPTION C<UNIVERSAL> is the base class which all bless references will inherit from, -see L<perlobj> +see L<perlobj>. -C<UNIVERSAL> provides the following methods +C<UNIVERSAL> provides the following methods and functions: =over 4 -=item isa ( TYPE ) - -C<isa> returns I<true> if C<REF> is blessed into package C<TYPE> -or inherits from package C<TYPE>. - -C<isa> can be called as either a static or object method call. - -=item can ( METHOD ) - -C<can> checks if the object has a method called C<METHOD>. If it does -then a reference to the sub is returned. If it does not then I<undef> -is returned. +=item $obj->isa( TYPE ), CLASS->isa( TYPE ), isa( VAL, TYPE ) -C<can> can be called as either a static or object method call. + C<TYPE> is a package name + $obj is a blessed reference or a string containing a package name + C<CLASS> is a package name + C<VAL> is any of the above or an unblessed reference -=item VERSION ( [ REQUIRE ] ) - -C<VERSION> will return the value of the variable C<$VERSION> in the -package the object is blessed into. If C<REQUIRE> is given then -it will do a comparison and die if the package version is not -greater than or equal to C<REQUIRE>. - -C<VERSION> can be called as either a static or object method call. +When used as an instance or class method (C<$obj->isa( TYPE )>), C<isa> +returns I<true> if $obj is blessed into package C<TYPE> or inherits from +package C<TYPE>. -=back +When used as a class method (C<CLASS->isa( TYPE )>; sometimes referred to as a +static method), C<isa> returns I<true> if C<CLASS> inherits from (or is itself) +the name of the package C<TYPE> or inherits from package C<TYPE>. -The C<isa> and C<can> methods can also be called as subroutines +When used as a function, like -=over 4 + use UNIVERSAL qw( isa ) ; + $yes = isa $h, "HASH"; + $yes = isa "Foo", "Bar"; -=item UNIVERSAL::isa ( VAL, TYPE ) +or -C<isa> returns I<true> if one of the following statements is true. + require UNIVERSAL ; + $yes = UNIVERSAL::isa $a, "ARRAY"; -=over 8 +, C<isa> returns I<true> in the same cases as above and also if C<VAL> is an +unblessed reference to a perl variable of type C<TYPE>, such as "HASH", +"ARRAY", or "Regexp". -=item * +=item $obj->can( METHOD ), CLASS->can( METHOD ), can( VAL, METHOD ) -C<VAL> is a reference blessed into either package C<TYPE> or a package -which inherits from package C<TYPE>. +C<can> checks if the object or class has a method called C<METHOD>. If it does +then a reference to the sub is returned. If it does not then I<undef> is +returned. This includes methods inherited or imported by C<$obj>, C<CLASS>, or +C<VAL>. -=item * +C<can> cannot know whether an object will be able to provide a method +through AUTOLOAD, so a return value of I<undef> does not necessarily mean +the object will not be able to handle the method call. To get around +this some module authors use a forward declaration (see L<perlsub>) +for methods they will handle via AUTOLOAD. For such 'dummy' subs, C<can> +will still return a code reference, which, when called, will fall through +to the AUTOLOAD. If no suitable AUTOLOAD is provided, calling the coderef +will cause an error. -C<VAL> is a reference to a C<TYPE> of Perl variable (e.g. 'HASH'). +C<can> can be called as a class (static) method, an object method, or a +function. -=item * +When used as a function, if C<VAL> is a blessed reference or package name which +has a method called C<METHOD>, C<can> returns a reference to the subroutine. +If C<VAL> is not a blessed reference, or if it does not have a method +C<METHOD>, I<undef> is returned. -C<VAL> is the name of a package that inherits from (or is itself) -package C<TYPE>. +=item VERSION ( [ REQUIRE ] ) -=back +C<VERSION> will return the value of the variable C<$VERSION> in the +package the object is blessed into. If C<REQUIRE> is given then +it will do a comparison and die if the package version is not +greater than or equal to C<REQUIRE>. -=item UNIVERSAL::can ( VAL, METHOD ) +C<VERSION> can be called as either a class (static) method, an object method or +or a function. -If C<VAL> is a blessed reference which has a method called C<METHOD>, -C<can> returns a reference to the subroutine. If C<VAL> is not -a blessed reference, or if it does not have a method C<METHOD>, -I<undef> is returned. =back |