OpenBSD::PackingList(3p) Perl Programmers Reference Guide
NAMEOpenBSD::PackingList - "pkg_add(1)" packing-list manipulations
SYNOPSIS
use OpenBSD::PackingList;
# different methods to create packing-lists
my $p1 = OpenBSD::PackingList->new; # empty
my $p2 = OpenBSD::PackingList->read($fh);
my $p3 = OpenBSD::PackingList->fromfile($filename);
my $p4 = OpenBSD::PackingList->fromfile(\$scalar);
my $p5 = OpenBSD::PackingList->from_installation($pkgname);
# writing packing-lists
$p2->write($fh);
$p3->tofile($filename);
$p4->to_installation;
$p4->to_cache;
# building up packing-lists
OpenBSD::PackingElement::SUBCLASS->add($plist, @args);
my $o = OpenBSD::PackingElement::SUBCLASS->new(@args);
$o->add_object($plist);
# tests and access
$b = $p2->has($name);
$b = $p2->get($name);
# frequent accesses
print $p3->pkgname, $p3->localbase, "\n";
# processing packing-lists
$p4->visit('method', @args);
# auto visit
$p4->method(@args);
# signatures
if ($p3->signature eq $p4->signature) {
}
DESCRIPTION
"OpenBSD::PackingList" is the only supported interface for access to
packing-list information. It includes conversion methods from an
external textual representation (file) into an internal structured
representation. Basically, a packing-list is a collection of
strongly-typed objects. Some of these objects are just properties of
the package (like the package name, or dependencies), some objects have
long lists of properties (files come with MD5 checksums, sizes, or
linknames), some objects represent state information (like file modes)
and must be kept in the proper order. The "OpenBSD::PackingList" class
handles all that.
Packing-lists can be obtained using the following methods: from an
opened file handle using "OpenBSD::PackingList->read($fh)", from an
existing file using "OpenBSD::PackingList->fromfile($filename)", from a
scalar in memory using "OpenBSD::PackingList->fromfile(\$scalar)", or
from an installed package using
"OpenBSD::PackingList->from_installation($pkgname)".
Since building a full packing-list is a complex operation and can
consume a large amount of memory, those methods may take an extra
argument in order to obtain partial packing-lists with only some
information:
SharedItemsOnly read only stuff that may be shared between packages,
e.g., new users, groups and directories.
LibraryOnly read only shared library entries.
FilesOnly read only files without the associated annotations like
size or MD5.
DependOnly read only dependency information.
ExtraInfoOnly read only the extra information field.
UpdateInfoOnly read only what is needed to decide to update a package.
PrelinkStuffOnly
read only what is need to figure out all binary/library
information, e.g., libraries, dependencies and
binaries.
A complete packing-list $plist may be written to disk using the
following methods: "$plist->write($fh)" will write a packing-list to an
opened file handle $fh, "$plist->tofile($filename)" will write a
packing-list to a file named $filename, and "$plist->to_installation"
will write a packing-list during registration of a package.
In addition "$plist->to_cache" will register enough information from a
package to let the framework believe the package has been installed.
This is used for the simulation modes of pkg_add(1) and friends.
Since a packing-list is structured information, reading a packing-list
from the disk and writing it back offers no guarantee the information
will remain in the same order. It is a good way to validate
packing-lists and normalize them, though.
Building packing-lists entails cooperation with
"OpenBSD::PackingElement". Packing-lists are usually built by adding
objects from an "OpenBSD::PackingElement" subclass to the packing-list,
either with the "add" constructor:
"OpenBSD::PackingElement::SUBCLASS->add($plist, $args)", which builds a
packing element and adds it to the packing-list in one operation, or
with the "add_object" method, which takes an existing packing element
and adds it to the packing-list (note that "add_object" only makes
sense for subclasses of "OpenBSD::PackingElement::Object"). See
OpenBSD::PackingElement for more details.
"$plist->pkgname" retrieves a packing-list name (mandatory).
"$plist->signature" retrieves a packing-list full signature, composed
of the package name and dependency information.
"$plist->visit($method, @args)" is a visitor pattern, calling
"method(@args)" on each element of the packing-list in a specific
order.
As a feature, if "OpenBSD::PackingElement->can(method)",
"$plist->method(@args)" will be turned into a visitor call
automatically.
perl v5.12.2 January 2, 2011
