# phpman > man > Dpkg::Deps::KnownFacts

## NAME
    [Dpkg::Deps::KnownFacts](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3ADeps%3A%3AKnownFacts/markdown) - list of installed real and virtual packages

## DESCRIPTION
    This class represents a list of installed packages and a list of virtual packages provided (by
    the set of installed packages).

## METHODS
    $facts = [Dpkg::Deps::KnownFacts](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3ADeps%3A%3AKnownFacts/markdown)->new();
        Creates a new object.

    $facts->add_installed_package($package, $version, $arch, $multiarch)
        Records that the given version of the package is installed. If $version/$arch is undefined
        we know that the package is installed but we don't know which version/architecture it is.
        $multiarch is the Multi-Arch field of the package. If $multiarch is undef, it will be
        equivalent to "Multi-Arch: no".

        Note that $multiarch is only used if $arch is provided.

    $facts->add_provided_package($virtual, $relation, $version, $by)
        Records that the "$by" package provides the $virtual package. $relation and $version
        correspond to the associated relation given in the Provides field (if present).

    $facts->evaluate_simple_dep()
        This method is private and should not be used except from within [Dpkg::Deps](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3ADeps/markdown).

## CHANGES
  Version 2.00 (dpkg 1.20.0)
    Remove method: $facts->check_package().

  Version 1.01 (dpkg 1.16.1)
    New option: [Dpkg::Deps::KnownFacts](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3ADeps%3A%3AKnownFacts/markdown)->add_installed_package() now accepts 2 supplementary
    parameters ($arch and $multiarch).

    Deprecated method: [Dpkg::Deps::KnownFacts](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3ADeps%3A%3AKnownFacts/markdown)->check_package() is obsolete, it should not have been
    part of the public API.

  Version 1.00 (dpkg 1.15.6)
    Mark the module as public.