decorators.py
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"""Service-side D-Bus decorators.""" # Copyright (C) 2003, 2004, 2005, 2006 Red Hat Inc. <http://www.redhat.com/> # Copyright (C) 2003 David Zeuthen # Copyright (C) 2004 Rob Taylor # Copyright (C) 2005, 2006 Collabora Ltd. <http://www.collabora.co.uk/> # # Permission is hereby granted, free of charge, to any person # obtaining a copy of this software and associated documentation # files (the "Software"), to deal in the Software without # restriction, including without limitation the rights to use, copy, # modify, merge, publish, distribute, sublicense, and/or sell copies # of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be # included in all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER # DEALINGS IN THE SOFTWARE. __all__ = ('method', 'signal') __docformat__ = 'restructuredtext' import inspect from dbus import validate_interface_name, Signature, validate_member_name from dbus.lowlevel import SignalMessage from dbus.exceptions import DBusException from dbus._compat import is_py2 def 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 """ validate_interface_name(dbus_interface) def decorator(func): if hasattr(inspect, 'Signature'): args = [] for arg in inspect.signature(func).parameters.values(): if arg.kind in (inspect.Parameter.POSITIONAL_ONLY, inspect.Parameter.POSITIONAL_OR_KEYWORD): args.append(arg.name) else: args = inspect.getargspec(func)[0] args.pop(0) if async_callbacks: if type(async_callbacks) != tuple: raise TypeError('async_callbacks must be a tuple of (keyword for return callback, keyword for error callback)') if len(async_callbacks) != 2: raise ValueError('async_callbacks must be a tuple of (keyword for return callback, keyword for error callback)') args.remove(async_callbacks[0]) args.remove(async_callbacks[1]) if sender_keyword: args.remove(sender_keyword) if rel_path_keyword: args.remove(rel_path_keyword) if path_keyword: args.remove(path_keyword) if destination_keyword: args.remove(destination_keyword) if message_keyword: args.remove(message_keyword) if connection_keyword: args.remove(connection_keyword) if in_signature: in_sig = tuple(Signature(in_signature)) if len(in_sig) > len(args): raise ValueError('input signature is longer than the number of arguments taken') elif len(in_sig) < len(args): raise ValueError('input signature is shorter than the number of arguments taken') func._dbus_is_method = True func._dbus_async_callbacks = async_callbacks func._dbus_interface = dbus_interface func._dbus_in_signature = in_signature func._dbus_out_signature = out_signature func._dbus_sender_keyword = sender_keyword func._dbus_path_keyword = path_keyword func._dbus_rel_path_keyword = rel_path_keyword func._dbus_destination_keyword = destination_keyword func._dbus_message_keyword = message_keyword func._dbus_connection_keyword = connection_keyword func._dbus_args = args func._dbus_get_args_options = dict(byte_arrays=byte_arrays) if is_py2: func._dbus_get_args_options['utf8_strings'] = kwargs.get( 'utf8_strings', False) elif 'utf8_strings' in kwargs: raise TypeError("unexpected keyword argument 'utf8_strings'") return func return decorator def 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 """ validate_interface_name(dbus_interface) if path_keyword is not None: from warnings import warn warn(DeprecationWarning('dbus.service.signal::path_keyword has been ' 'deprecated since dbus-python 0.82.0, and ' 'will not work on objects that support ' 'multiple object paths'), DeprecationWarning, stacklevel=2) if rel_path_keyword is not None: raise TypeError('dbus.service.signal::path_keyword and ' 'rel_path_keyword cannot both be used') def decorator(func): member_name = func.__name__ validate_member_name(member_name) def emit_signal(self, *args, **keywords): abs_path = None if path_keyword is not None: if self.SUPPORTS_MULTIPLE_OBJECT_PATHS: raise TypeError('path_keyword cannot be used on the ' 'signals of an object that supports ' 'multiple object paths') abs_path = keywords.pop(path_keyword, None) if (abs_path != self.__dbus_object_path__ and not self.__dbus_object_path__.startswith(abs_path + '/')): raise ValueError('Path %r is not below %r', abs_path, self.__dbus_object_path__) rel_path = None if rel_path_keyword is not None: rel_path = keywords.pop(rel_path_keyword, None) func(self, *args, **keywords) for location in self.locations: if abs_path is None: # non-deprecated case if rel_path is None or rel_path in ('/', ''): object_path = location[1] else: # will be validated by SignalMessage ctor in a moment object_path = location[1] + rel_path else: object_path = abs_path message = SignalMessage(object_path, dbus_interface, member_name) message.append(signature=signature, *args) location[0].send_message(message) # end emit_signal args = inspect.getargspec(func)[0] args.pop(0) for keyword in rel_path_keyword, path_keyword: if keyword is not None: try: args.remove(keyword) except ValueError: raise ValueError('function has no argument "%s"' % keyword) if signature: sig = tuple(Signature(signature)) if len(sig) > len(args): raise ValueError('signal signature is longer than the number of arguments provided') elif len(sig) < len(args): raise ValueError('signal signature is shorter than the number of arguments provided') emit_signal.__name__ = func.__name__ emit_signal.__doc__ = func.__doc__ emit_signal._dbus_is_signal = True emit_signal._dbus_interface = dbus_interface emit_signal._dbus_signature = signature emit_signal._dbus_args = args return emit_signal return decorator
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