UNIVERSAL - base class for ALL classes (blessed references)

- NAME
- SYNOPSIS
- DESCRIPTION

# 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.