UNIVERSAL(3)

NNAAMMEE
       UNIVERSAL - base class for ALL classes (blessed
       references)

SSYYNNOOPPSSIISS
           $io = $fd->isa("IO::Handle");
           $sub = $obj->can('print');

           $yes = UNIVERSAL::isa($ref, "HASH");

DDEESSCCRRIIPPTTIIOONN
       UNIVERSAL is the base class which all bless references
       will inherit from, see the perlobj manpage

       UNIVERSAL provides the following methods

       isa ( TYPE )
           isa returns true if REF is blessed into package TYPE
           or inherits from package TYPE.

           isa can be called as either a static or object method
           call.

       can ( METHOD )
           can checks if the object has a method called METHOD.
           If it does then a reference to the sub is returned. If
           it does not then undef is returned.

           can can be called as either a static or object method
           call.

       VERSION ( [ REQUIRE ] )
           VERSION will return the value of the variable $VERSION
           in the package the object is blessed into. If REQUIRE
           is given then it will do a comparison and die if the
           package version is not greater than or equal to
           REQUIRE.

           VERSION can be called as either a static or object
           method call.

       The isa and can methods can also be called as subroutines

       UNIVERSAL::isa ( VAL, TYPE )
           isa returns true if the first argument is a reference
           and either of the following statements is true.
                   VAL is a blessed reference and is blessed into
                   package TYPE or inherits from package TYPE
                   VAL is a reference to a TYPE of perl variable
                   (er 'HASH')

       UNIVERSAL::can ( VAL, METHOD )
           If VAL is a blessed reference which has a method
           called METHOD, can returns a reference to the
           subroutine.   If VAL is not a blessed reference, or if
           it does not have a method METHOD, undef is returned.

       These subroutines should not be imported via use UNIVERSAL
       qw(...).  If you want simple local access to them you can
       do

         *isa = \&UNIVERSAL::isa;

       to import isa into your package.