UNIVERSAL - base class for ALL classes (blessed refer
ences)
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 `$VER
SION' 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 subrou
tines
UNIVERSAL::isa ( VAL, TYPE )
`isa' returns true if one of the following statements
is true.
· `VAL' is a reference blessed into either pack
age `TYPE' or a package which inherits from
package `TYPE'.
able (e.g. 'HASH').
· `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 sub
routine. 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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