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GNU/Linux man pages

Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :

ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)

GNU/Linux

CentOS 2.1AS

(Slurm)

UNIVERSAL(3pm)


UNIVERSAL

UNIVERSAL

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 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;

to import isa into your package.



UNIVERSAL(3pm)