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Diffstat (limited to 'Master/perltl/lib/UNIVERSAL.pm')
-rw-r--r-- | Master/perltl/lib/UNIVERSAL.pm | 118 |
1 files changed, 0 insertions, 118 deletions
diff --git a/Master/perltl/lib/UNIVERSAL.pm b/Master/perltl/lib/UNIVERSAL.pm deleted file mode 100644 index 92b4fcd352a..00000000000 --- a/Master/perltl/lib/UNIVERSAL.pm +++ /dev/null @@ -1,118 +0,0 @@ -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 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 VERSION); - -1; -__END__ - -=head1 NAME - -UNIVERSAL - base class for ALL classes (blessed references) - -=head1 SYNOPSIS - - $is_io = $fd->isa("IO::Handle"); - $is_io = Class->isa("IO::Handle"); - - $sub = $obj->can("print"); - $sub = Class->can("print"); - - 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>. - -C<UNIVERSAL> provides the following methods and functions: - -=over 4 - -=item $obj->isa( TYPE ), CLASS->isa( TYPE ), isa( VAL, TYPE ) - - C<TYPE> is a package name - $obj is a blessed reference or a string containing a package name - C<CLASS> is a package name - C<VAL> is any of the above or an unblessed reference - -When used as an instance or class method (C<$obj->isa( TYPE )>), C<isa> -returns I<true> if $obj is blessed into package C<TYPE> or inherits from -package C<TYPE>. - -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>. - -When used as a function, like - - use UNIVERSAL qw( isa ) ; - $yes = isa $h, "HASH"; - $yes = isa "Foo", "Bar"; - -or - - require UNIVERSAL ; - $yes = UNIVERSAL::isa $a, "ARRAY"; - -, 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 $obj->can( METHOD ), CLASS->can( METHOD ), can( VAL, METHOD ) - -C<can> checks if the object or class has a method called C<METHOD>. If it does -then a reference to the sub is returned. If it does not then I<undef> is -returned. This includes methods inherited or imported by C<$obj>, C<CLASS>, or -C<VAL>. - -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<can> can be called as a class (static) method, an object method, or a -function. - -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. - -=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 class (static) method, an object method or -or a function. - - -=back - -These subroutines should I<not> be imported via S<C<use UNIVERSAL qw(...)>>. -If you want simple local access to them you can do - - *isa = \&UNIVERSAL::isa; - -to import isa into your package. - -=cut |