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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 one of the following statements is
         true.

         o       `VAL' is a reference blessed into either package
                 `TYPE' or a package which inherits from package
                 `TYPE'.

         o       `VAL' is a reference to a `TYPE' of Perl
                 variable (e.g. 'HASH').

         o       `VAL' is the name of a package that inherits
                 from (or is itself) package `TYPE'.

     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.









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Created 1996-2024 by Maxim Chirkov

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