UNIVERSAL
Section: Perl Programmers Reference Guide
(3)
Updated: perl 5.004, patch 55
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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 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.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
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Time: 23:58:16 GMT, February 15, 2023