dbus.decorators module

Service-side D-Bus decorators.

dbus.decorators.method(dbus_interface, in_signature=None, out_signature=None, async_callbacks=None, sender_keyword=None, path_keyword=None, destination_keyword=None, message_keyword=None, connection_keyword=None, byte_arrays=False, rel_path_keyword=None, **kwargs)

Factory for decorators used to mark methods of a dbus.service.Object to be exported on the D-Bus.

The decorated method will be exported over D-Bus as the method of the same name on the given D-Bus interface.

Parameters:
dbus_interface : str

Name of a D-Bus interface

in_signature : str or None

If not None, the signature of the method parameters in the usual D-Bus notation

out_signature : str or None

If not None, the signature of the return value in the usual D-Bus notation

async_callbacks : tuple containing (str,str), or None

If None (default) the decorated method is expected to return values matching the out_signature as usual, or raise an exception on error. If not None, the following applies:

async_callbacks contains the names of two keyword arguments to the decorated function, which will be used to provide a success callback and an error callback (in that order).

When the decorated method is called via the D-Bus, its normal return value will be ignored; instead, a pair of callbacks are passed as keyword arguments, and the decorated method is expected to arrange for one of them to be called.

On success the success callback must be called, passing the results of this method as positional parameters in the format given by the out_signature.

On error the decorated method may either raise an exception before it returns, or arrange for the error callback to be called with an Exception instance as parameter.

sender_keyword : str or None

If not None, contains the name of a keyword argument to the decorated function, conventionally 'sender'. When the method is called, the sender’s unique name will be passed as this keyword argument.

path_keyword : str or None

If not None (the default), the decorated method will receive the destination object path as a keyword argument with this name. Normally you already know the object path, but in the case of “fallback paths” you’ll usually want to use the object path in the method’s implementation.

For fallback objects, rel_path_keyword (new in 0.82.2) is likely to be more useful.

Since:0.80.0?
rel_path_keyword : str or None

If not None (the default), the decorated method will receive the destination object path, relative to the path at which the object was exported, as a keyword argument with this name. For non-fallback objects the relative path will always be ‘/’.

Since:0.82.2
destination_keyword : str or None

If not None (the default), the decorated method will receive the destination bus name as a keyword argument with this name. Included for completeness - you shouldn’t need this.

Since:0.80.0?
message_keyword : str or None

If not None (the default), the decorated method will receive the dbus.lowlevel.MethodCallMessage as a keyword argument with this name.

Since:0.80.0?
connection_keyword : str or None

If not None (the default), the decorated method will receive the dbus.connection.Connection as a keyword argument with this name. This is generally only useful for objects that are available on more than one connection.

Since:0.82.0
utf8_strings : bool

If False (default), D-Bus strings are passed to the decorated method as objects of class dbus.String, a unicode subclass.

If True, D-Bus strings are passed to the decorated method as objects of class dbus.UTF8String, a str subclass guaranteed to be encoded in UTF-8.

This option does not affect object-paths and signatures, which are always 8-bit strings (str subclass) encoded in ASCII.

Since:0.80.0
byte_arrays : bool

If False (default), a byte array will be passed to the decorated method as an Array (a list subclass) of Byte objects.

If True, a byte array will be passed to the decorated method as a ByteArray, a str subclass. This is usually what you want, but is switched off by default to keep dbus-python’s API consistent.

Since:0.80.0
dbus.decorators.signal(dbus_interface, signature=None, path_keyword=None, rel_path_keyword=None)

Factory for decorators used to mark methods of a dbus.service.Object to emit signals on the D-Bus.

Whenever the decorated method is called in Python, after the method body is executed, a signal with the same name as the decorated method, with the given D-Bus interface, will be emitted from this object.

Parameters:
dbus_interface : str

The D-Bus interface whose signal is emitted

signature : str

The signature of the signal in the usual D-Bus notation

path_keyword : str or None

A keyword argument to the decorated method. If not None, that argument will not be emitted as an argument of the signal, and when the signal is emitted, it will appear to come from the object path given by the keyword argument.

Note that when calling the decorated method, you must always pass in the object path as a keyword argument, not as a positional argument.

This keyword argument cannot be used on objects where the class attribute SUPPORTS_MULTIPLE_OBJECT_PATHS is true.

Deprecated:since 0.82.0. Use rel_path_keyword instead.
rel_path_keyword : str or None

A keyword argument to the decorated method. If not None, that argument will not be emitted as an argument of the signal.

When the signal is emitted, if the named keyword argument is given, the signal will appear to come from the object path obtained by appending the keyword argument to the object’s object path. This is useful to implement “fallback objects” (objects which own an entire subtree of the object-path tree).

If the object is available at more than one object-path on the same or different connections, the signal will be emitted at an appropriate object-path on each connection - for instance, if the object is exported at /abc on connection 1 and at /def and /x/y/z on connection 2, and the keyword argument is /foo, then signals will be emitted from /abc/foo and /def/foo on connection 1, and /x/y/z/foo on connection 2.

Since:0.82.0