===============================

API changes in dbus-python 0.80

===============================

:Author: Simon McVittie

:Contact: simon.mcvittie@collabora.co.uk

:Organization: `Collabora Ltd`_

:Date: 2006-11-23

.. _Collabora Ltd: http://www.collabora.co.uk/

Type changes

============

* The Byte constructor accepts either single-byte strings, or integers in

  the range 0 to 255.

* There is no Variant type any more. Instead, the ``variant_level``

  attribute on D-Bus types gives the number of variant wrappers in

  which it is contained; this is to remove ambiguity. For instance, calling

  this method::

    @dbus.service.method('com.example', in_signature='v', out_signature='') 

    def Print(self, variant):

        print repr(variant)

  yields the following results::

    # on the wire: Variant containing Int32

    Int32(0, variant_level=1)

    # on the wire: Variant containing Variant containing Int32

    Int32(0, variant_level=2)

  Once an object of a D-Bus type has been constructed, its

  ``variant_level`` cannot be altered.

* The D-Bus integer types (dbus.Int32, etc.) are properly range-checked.

* The Array constructor takes arguments (iterable[, signature])

  rather than (iterable[, type][, signature]); ditto for Dict.

Calling conventions

===================

* In method parameters, method returns from proxy methods, etc.,

  integers arrive as instances of dbus.Int32 etc., bytes arrive as

  Byte, and so on, rather than everything being converted to an

  appropriate built-in Python type. This means you can tell exactly

  what arguments went over the bus, and their types.

* Proxy methods with multiple return values return a tuple rather than

  a list.

* Calling a proxy method with reply ignored, or with async

  handlers, returns None

``dbus_bindings``

=================

* ConnectionError no longer exists (it was never raised)

* ``dbus_bindings`` is now called ``_dbus_bindings``, and is considerably

  different internally:

  * connections are private at the libdbus level: shared connections

    are only shared among Python code

  * The MessageIter stuff is now done in C: there's a much simpler

    Python API, ``Message.append(...)`` where positional arguments are

    the things to be appended, and the keyword argument ``signature``

    controls how objects are interpreted

  * The signature-guessing algorithm used if there is no proper

    signature is exposed as a static method,

    ``Message.guess_signature(*args)``

  * Bus is a subclass of Connection rather than being a wrapper object

    which has-a Connection

  * The timeouts in _send_with_reply and in _send_with_reply_and_block

    are in (possibly fractional) seconds, as is conventional in Python

  * The specialized Message subclasses have names ending with Message

* There is a small amount of compatibility glue in a new

  ``dbus_bindings`` module (also ``dbus.dbus_bindings``)

  which should enable most current code to work - this is deprecated,

  and will disappear in a future version of dbus-python

Main loops

==========

Main loop handling is different - instead of the

``use_default_mainloop`` keyword argument to Bus and subclasses, there's now

``mainloop`` which takes an instance of dbus.mainloop.NativeMainLoop.

Alternatively, you can set a default main loop by calling

``dbus.set_default_main_loop()`` and passing it a NativeMainLoop, or

by passing ``set_as_default=True`` to the factory function

from which you obtained the native main loop.

The plan is that in a future version of dbus-python there will be an

abstract base class dbus.mainloop.MainLoop (or something); when it's added,

instances of its subclasses will be accepted wherever a NativeMainLoop

instance is now. This will let you wrap main loops using a Python API.

This will be used to implement SimpleMainLoop (a pure-Python main loop

which can only do D-Bus) and a Twisted main-loop wrapper.

The only working mainloop implementation is (still) GLib; you can get

a NativeMainLoop instance by::

  from dbus.mainloop.glib import DBusGMainLoop

  my_native_main_loop = DBusGMainLoop(set_as_default=True)

The above is how the highly magical ``dbus.glib`` module is now implemented.

At some point ``dbus.glib`` will be deprecated, since it's non-obvious,

and pychecker will usually complain if you use it correctly!

At the moment the GLib main loop always uses the default main context;

python-gobject will probably need to add some extra API before we can

allow other main-contexts to be used.

..

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