$OpenBSD: OpenBSD::PackingElement.pod,v 1.6 2005/08/17 19:28:24 espie Exp $

=head1 NAME

OpenBSD::PackingElement - C<pkg_add(1)> packing-elements object hierarchy

=head1 SYNOPSIS

    package OpenBSD::PackingElement;
    sub method
    {
    }

    package OpenBSD::PackingElement::Depend;
    sub method
    {
    	my ($self, @args) = @_;
	# do something
    }

    package main;
    use OpenBSD::PackingList;

    $plist = OpenBSD::PackingList->fromfile($filename);
    $plist->visit('method', @args);

=head1 DESCRIPTION

C<OpenBSD::PackingElement> is the base class for all elements in a 
packing-list (see L<OpenBSD::PackingList(3p)> and C<pkg_create(1)>).

Manipulation of packing-lists mostly occurs through visitor patterns
such as C<OpenBSD::PackingList::visit>: client code defines a method for
each relevant class in the hierarchy and calls C<$plist-E<gt>visit('method')>
to perform the processing.

Most actual objects have one property: their C<name>.

=over 4

=item ::Meta

base class for all meta information that can be reordered at will.

=over 4

=item ::Unique

meta information with uniqueness properties.

=over 4

=item ::Arch

architecture requirements.

=item ::ExtraInfo

some unique properties, like C<PKGPATH> and allowed-for-ftp status.

=item ::Name

the package name.

=item ::LocalBase

the local base for the package.

=item ::NoDefaultConflict

special annotation that package should not have any C<stem-*> conflict marker.

=item ::SpecialFile

special files like the package description or install script.

=over 4

=item ::FCONTENTS

contents file.

=item ::FCOMMENT

comment file. Deprecated.

=item ::FDESC

package description.

=item ::FREQUIRE

registration of forward dependencies (see L<OpenBSD::RequiredBy(3p)>).

=item ::FREQUIRED_BY

registration of reverse dependencies.

=item ::FMTREE_DIRS

deprecated

=item ::DisplayFile

abstract class for special files that can be displayed.
provides method C<prepare($state)> to display the file.

=over 4

=item ::FDISPLAY

message displayed during package install.

=item ::FUNDISPLAY

message displayed during package uninstall.

=back

=item ::ScriptFile

abstract class for special files that can be run.
provides method C<run($state, @args)> to run the script.

=over 4

=item ::FINSTALL

INSTALL script.

=item ::FDEINSTALL

DEINSTALL script.

=item ::FREQUIRE

REQUIRE script.

=back

=back

=back

=item ::Option

factory for C<@option>

=item ::Comment

comments in the packing-lists. The constructor is actually a factory,
since some comments evolve to some other class.

=item ::CVSTag

special class of comments that get reordered to the front of packing-lists.

=item ::Depend

all dependency information.

=over 4

=item ::PkgDep

deprecated.

=item ::NewDepend

deprecated.

=item ::LibDepend

deprecated.

=item ::Wantlib

shared library needed for the package.

=item ::Dependency

package needed, with the following properties: C<pkgpath> is the path
used to create the dependency, C<pattern> is the L<OpenBSD::PkgSpec(3p)>
pattern used to match the dependency, C<def> is the default value of
the dependency computed during build, to use for comparing package signatures
and to fullfill default dependencies.

=back

=item ::Conflict

conflict information.

=over 4

=item ::PkgConflict

deprecated.

=back

=back

=item ::Annotation

stuff that doesn't really exist as objects, but is used to add
properties to objects.

=over 4

=item ::Ignore

mark next object as ignored.

=item ::md5

mark last file with a checksum.

=item ::size

mark last file with a size.

=item ::symlink

mark last file as a symlink.

=item ::hardlink

mark last file as a hardlink.

=item ::temp

mark last file with a temporary name. Used during extraction of
packages for replacement.

=back

=item ::Object

somewhat concrete elements in packing-lists.
This is the base class for objects with a location in the filesystem.
It defineds method C<fullname>, to access the complete name of the object.

Note that all objects with file names use relative names except for
C<::Extra>, C<::Sample> and C<::Sampledir>

=over 4

=item ::FileObject

abstract class corresponding to files and directories.
Default constructor depends on a C<dirclass> property, that may
create objects from another class if their name ends with a C</>.
The full object name is normally computed relative to the current 
working directory as set in C<::State>.

=over 4

=item ::FileBase

abstract class for files.

=over 4

=item ::File

actual file objects present in the packing-list.

=item ::InfoFile

GNU info file objects.

=item ::Shell

files with shell properties.

=item ::Manpage

man pages.

=item ::Lib

shared library files.

=item ::Sample

file objects not present in the packing-list.

=for comment  ::Extra and ::Extradir intentionally not documented yet.

=back

=item ::DirlikeObject

abstract class for directories.

=over 4

=item ::DirRm

deprecated.

=item ::DirBase

=over 4

=item ::Dir

normal directory, with specialized versions.

=over 4

=item ::Infodir

directory holds GNU info files.

=item ::Fontdir

directory holds X11 fonts.

=item ::Mandir

directory is the root of a set of manpages.

=item ::Sampledir

directory is used to hold configuration files or similar objects.

=back

=back

=back

=back

=item ::Action

stuff that performs some action during addition/removal of package.

=over 4

=item ::NewUser

user that needs to be created for the package to work.

=item ::NewGroup

group that needs to be created for the package to work.

=item ::Sysctl

C<sysctl(8)> property needed for the package to work.

=item ::ExeclikeAction

escape mechanism for embedded code that needs to be run.

=over 4

=item ::Exec

code to run during installation.

=item ::Unexec

code to run during deinstallation.

=item ::Extraunexec

extra code to run during deinstallation with -c.

=back

=back

=item ::State

annotation-like stuff that can't be easily moved around because it influences
surrounding objects (mostly derived from C<::FileObject>).

=over 4

=item ::Cwd

change the current working directory.

=item ::EndFake

=item ::Owner

change the current file owner.

=item ::Group

change the current file group.

=item ::Mode

change the current file mode.

=back

=back

=back

=head1 CAVEATS

Some aspects of this API are likely to change in the future, although the
basic class hierarchy is now more or less worked out.