UNIVERSAL(3)

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

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

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


DESCRIPTION
     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.