package UNIVERSAL; # 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. require Exporter; *import = \&Exporter::import; @EXPORT_OK = qw(isa can); 1; __END__ =head1 NAME UNIVERSAL - base class for ALL classes (blessed references) =head1 SYNOPSIS $io = $fd->isa("IO::Handle"); $sub = $obj->can('print'); $yes = UNIVERSAL::isa($ref, "HASH"); =head1 DESCRIPTION C is the base class which all bless references will inherit from, see L C provides the following methods =over 4 =item isa ( TYPE ) C returns I if C is blessed into package C or inherits from package C. C can be called as either a static or object method call. =item can ( METHOD ) C checks if the object has a method called C. If it does then a reference to the sub is returned. If it does not then I is returned. C can be called as either a static or object method call. =item VERSION ( [ REQUIRE ] ) C will return the value of the variable C<$VERSION> in the package the object is blessed into. If C is given then it will do a comparison and die if the package version is not greater than or equal to C. C can be called as either a static or object method call. =back The C and C methods can also be called as subroutines =over 4 =item UNIVERSAL::isa ( VAL, TYPE ) C returns I if the first argument is a reference and either of the following statements is true. =over 8 =item C is a blessed reference and is blessed into package C or inherits from package C =item C is a reference to a C of perl variable (er 'HASH') =back =item UNIVERSAL::can ( VAL, METHOD ) If C is a blessed reference which has a method called C, C returns a reference to the subroutine. If C is not a blessed reference, or if it does not have a method C, I is returned. =back These subroutines should I be imported via S>. If you want simple local access to them you can do *isa = \&UNIVERSAL::isa; to import isa into your package. =cut