Currently it comes with the following main features:
- Programming language independent D-Bus interface, which allows to write clients in several languages
- Transaction based design which allows to queue actions
- The daemon runs only if required (D-Bus activation)
- Fine grained privilege management using PolicyKit, e.g. allowing alldesktop user to query for updates without entering a password
- Support for media changes during installation from DVD/CDROM
- Support for debconf (Debian's package configuration system)
- Support for attaching a terminal to the underlying dpkg call
- Command line client aptdcon
- Python GTK widgets to monitor and control a running transaction

Aptdaemon was inspired by PackageKit which doesn't allow a tightintegration into Debian/Ubuntu by policy: Running transaction are notallowed to be paused. This makes the use of debconf or resolving configfile conflicts impossible.

The documentation can be found at the home page.

DBus driven daemon for APT

Aptdaemon allows to perform package management tasks in a background processcontrolled by DBus. It is greatly inspired by PackageKit, which doesn't supportessential features of apt by policy.

http://pypi.python.org/pypi/aptdaemon/0.40

What is D-Bus?

D-Bus is amessage bus system, a simple way for applications to talk to oneanother. In addition to interprocess communication, D-Bus helpscoordinate process lifecycle; it makes it simple and reliable to code a"single instance" application or daemon, and to launch applications anddaemons on demand when their services are needed.

D-Bussupplies both a system daemon (for events such as "new hardware deviceadded" or "printer queue changed") and a per-user-login-session daemon(for general IPC needs among user applications). Also, the message busis built on top of a general one-to-one message passing framework, whichcan be used by any two apps to communicate directly (without goingthrough the message bus daemon). Currently the communicatingapplications are on one computer, or through unencrypted TCP/IP suitablefor use behind a firewall with shared NFS home directories. (Helpwanted with better remote transports - the transport mechanism is well-abstracted and extensible.)

The D-Bus low-level API reference implementation and protocolhave been heavily tested in the real world over several years, and arenow "set in stone." Future changes will either be compatible orversioned appropriately.

Thelow-level libdbus reference implementation has no requireddependencies; the bus daemon's only *required* dependency is an XMLparser (either libxml or expat). Higher-level bindings specific toparticular frameworks (Qt, GLib, Java, C#, Python, etc.) add moredependencies, but can make more assumptions and are thus much simpler touse. The bindings evolve separately from the low-level libdbus, so someare more mature and ABI-stable than others; check the docs for thebinding you plan to use.

Thereare also some reimplementations of the D-Bus protocol for languagessuch as C#, Java, and Ruby. These do not use the libdbus referenceimplementation.

Python signals are indicated by thePYSIGNAL() function, which also takes astring. There is no PYSLOT() functioncorresponding to SLOT(), because you canuse any function as a slot inPython.

The argument of PYSIGNAL() is a simplestring that is unique for the class from which the signal isemitted. It performs the same function as theoccasion string in the smallregistry.py script. The difference is thatPYSIGNAL() string needs to be unique onlyfor the class, and not the whole application.

Table 7-1. Matrix ofQObject.connect()combinations.

Table 7-1. Matrix ofQObject.connect()combinations.

python pass

pass语句什么也不做，一般作为占位符或者创建占位程序，pass语句不会执行任何操作，比如：

while False:

pass

pass通常用来创建一个最简单的类：

class MyEmptyClass:

pass

pass在软件设计阶段也经常用来作为TODO，提醒实现相应的实现，比如：

def initlog(*args):

pass #please implement this

http://apt.alioth.debian.org/python-apt-doc/library/index.html

Python APT’s library provides access to almost every functionality supportedby the underlying apt-pkg and apt-inst libraries. This means that it ispossible to rewrite frontend programs like apt-cdrom in Python, and this isrelatively easy, as can be seen in e.g. Writing your own apt-cdrom.

When going through the library, the first two modules are apt_pkg andapt_inst. These modules are more or less straight bindings to theapt-pkg and apt-inst libraries and the base for the rest of python-apt.

Going forward, the apt package appears. This package is usingapt_pkg and :mod`apt_inst` to provide easy to use ways to manipulatethe cache, fetch packages, or install new packages. It also provides usefulprogress classes, for text and GTK+ interfaces. The last package isaptsources. The aptsources package provides classes and functions toread files like /etc/apt/sources.list and to modify them.

lass apt.cache.Cache(progress=None, rootdir=None, memonly=False)

Dictionary-like package cache.

This class has all the packages that are available in it’sdictionary.

Keyword arguments:progress – a OpProgress objectrootdir – a alternative root directory. if that is given

the system sources.list and system lists/ files arenot read, only files relative to the given rootdir

memonly – build the cache in memory only

cache[pkgname]

Return a Package() for the package with the name pkgname.