Manpages

UNIVERSAL

NAME

SYNOPSIS

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

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

DESCRIPTION

"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.

*

"VAL" is a reference blessed into either package "TYPE" or a package which inherits from package "TYPE".

*

"VAL" is a reference to a "TYPE" of Perl variable (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 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;

Index

NAME

SYNOPSIS

DESCRIPTION