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=head1 DATA TYPES

Several libalpm data types have been converted into hash references. The
alternative is to turn them into full-blown objects, which seems pointless
considering the only methods are data accessors.

=head2 Dependency

Dependencies specify constraints on a set of packages. Only certain packages
satisfy a dependency. These can be used in places other than dependencies,
such as conflicts. Dependencies have the following keys:

=over 4

=item name

The name of a package.

=item version

A version string, which can be empty.

=item mod

A boolean operator used to compare package versions to our dependency
version, must be either an empty string (which allows any version), =, >=,
<=, >, <, or ? if an internal error occurred.

=item desc

If the dependency is optional this key gives a description of the dependency. This key does not exist on a regular dependency.

=back

=head2 Conflict

Conflicts have the following keys:

=over 4

=item package1

An L<ALPM::Package> object.

=item package2

An L<ALPM::Package> object.

=item reason

A hashref that is identical to a dependency. See L</Dependency>.

=back

=head2 Signature Level

Signature levels describe the level of security which is required for packages files
and by databases files. Different degrees of signature checking can be used for
either type of file. The signature checking is performed after the file is downloaded
in order to verify the original packager. B<When gpg is not available an invalid argument
error will be raised from libalpm if you try to set the siglevel.>

A "siglvl" can either be the string C<"default"> or a hash reference. A value of C<"default">
can be used when registering a database to instruct libalpm to use the default siglevel
that is set by I<set_defsiglvl>. A siglvl hashref must contain a C<"pkg"> key
and a C<"db"> key. Other keys are ignored.

Possible hash values include:

=over 4

=item C<"never">

No signature verification is performed.

=item C<"optional">

Signatures are optional. They are checked if they are available.

=item C<"required">

Signatures are required.

=back

The string C<"trustall">, preceded by a space, can be added to C<"optional"> or
C<"required"> options to specify that signatures from anyone are to be trusted.

Here are some example siglevels:

  $alpm->set_defsiglvl({ 'pkg' => 'never', 'db' => 'never' });
  $alpm->set_defsiglvl({ 'pkg' => 'optional', 'db' => 'required trustall' });
  $alpm->set_defsiglvl({ 'pkg' => 'required', 'db' => 'optional' });

=head1 ERRORS

In previous version of this module, errors were thrown automatically. Since then,
errors are no longer stored in a global variable (like UNIX's errno) but are instead
stored inside of the libalpm handle structure. In order to preserve the old functionality
I will have to either store a copy of the ALPM object inside every other object or use
the internal C representation which I'm technically not supposed to know.

Whatever. I'm too lazy for either of those. What this means for you is you really really
should check for errors yourself. If a method call returns undef you should follow it
up with an "or die". Something like this:

  $db->force_update or die $alpm->strerror;

This is annoying but not unlike most other perl error checking. If you find yourself
calling methods on an undefined value then an error most likely occurred.

But wait there's more! Errors are actually thrown when getting/setting options and
an error condition occurs.

=head1 SEE ALSO

=over

=item * L<ALPM::Conf>, L<ALPM::DB>, L<ALPM::Package>, L<ALPM::Transaction>