dbus/python service.py,1.13,1.14
Robert McQueen
robot101 at freedesktop.org
Thu Nov 3 13:47:33 PST 2005
Update of /cvs/dbus/dbus/python
In directory gabe:/tmp/cvs-serv16001/python
Modified Files:
service.py
Log Message:
2005-11-03 Robert McQueen <robot101 at debian.org>
* python/service.py: Heavy refactoring of method invocation, with
hopefully no effect on functionality. Nuked _dispatch_dbus_method_call
in favour of a new _message_cb that uses seperate functions for
looking up the method to call, marshalling the return values, and
sending exceptions as errors, and is easier to follow as a
consequence. Fixes some corner cases about returning things that
don't match your declared out_signature, allows exceptions to define
_dbus_error_name and have it be sent over the bus as the error name,
and paves the way for cool stuff like heeding the message no reply
flag, asynchronous method implementations, informing the method of the
sender, and including backtraces in the error messages.
* test/python/test-client.py: Catch and print exceptions thrown in the
async callback tests, rather than passing them to the low-level
bindings to be ignored in a noisy and frustrating manner.
Index: service.py
===================================================================
RCS file: /cvs/dbus/dbus/python/service.py,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -d -r1.13 -r1.14
--- service.py 3 Nov 2005 16:13:52 -0000 1.13
+++ service.py 3 Nov 2005 21:47:31 -0000 1.14
@@ -32,118 +32,110 @@
return '<dbus.service.BusName %s on %r at %#x>' % (self._named_service, self._bus, id(self))
__str__ = __repr__
-def _dispatch_dbus_method_call(self, argument_list, message):
- """Calls method_to_call using argument_list, but handles
- exceptions, etc, and generates a reply to the DBus Message message
+
+def _method_lookup(self, method_name, dbus_interface):
+ """Walks the Python MRO of the given class to find the method to invoke.
+
+ Returns two methods, the one to call, and the one it inherits from which
+ defines its D-Bus interface name, signature, and attributes.
"""
- try:
- method_name = message.get_member()
- dbus_interface = message.get_interface()
- candidate = None
- successful = False
+ parent_method = None
+ candidate_class = None
+ successful = False
- # split up the cases when we do and don't have an interface because the
- # latter is much simpler
- if dbus_interface:
- # search through the class hierarchy in python MRO order
- for cls in self.__class__.__mro__:
- # if we haven't got a candidate yet, and we find a class with a
- # suitably named member, save this as a candidate
- if (not candidate and method_name in cls.__dict__):
- if ("_dbus_is_method" in cls.__dict__[method_name].__dict__
- and "_dbus_interface" in cls.__dict__[method_name].__dict__):
- # however if it is annotated for a different interface
- # than we are looking for, it cannot be a candidate
- if cls.__dict__[method_name]._dbus_interface == dbus_interface:
- candidate = cls
- sucessful = True
- target_parent = cls.__dict__[method_name]
- break
- else:
- pass
+ # split up the cases when we do and don't have an interface because the
+ # latter is much simpler
+ if dbus_interface:
+ # search through the class hierarchy in python MRO order
+ for cls in self.__class__.__mro__:
+ # if we haven't got a candidate class yet, and we find a class with a
+ # suitably named member, save this as a candidate class
+ if (not candidate_class and method_name in cls.__dict__):
+ if ("_dbus_is_method" in cls.__dict__[method_name].__dict__
+ and "_dbus_interface" in cls.__dict__[method_name].__dict__):
+ # however if it is annotated for a different interface
+ # than we are looking for, it cannot be a candidate
+ if cls.__dict__[method_name]._dbus_interface == dbus_interface:
+ candidate_class = cls
+ parent_method = cls.__dict__[method_name]
+ sucessful = True
+ break
else:
- candidate = cls
+ pass
+ else:
+ candidate_class = cls
- # if we have a candidate, carry on checking this and all
- # superclasses for a method annoated as a dbus method
- # on the correct interface
- if (candidate and method_name in cls.__dict__
- and "_dbus_is_method" in cls.__dict__[method_name].__dict__
- and "_dbus_interface" in cls.__dict__[method_name].__dict__
- and cls.__dict__[method_name]._dbus_interface == dbus_interface):
- # the candidate is a dbus method on the correct interface,
- # or overrides a method that is, success!
- target_parent = cls.__dict__[method_name]
- sucessful = True
- break
+ # if we have a candidate class, carry on checking this and all
+ # superclasses for a method annoated as a dbus method
+ # on the correct interface
+ if (candidate_class and method_name in cls.__dict__
+ and "_dbus_is_method" in cls.__dict__[method_name].__dict__
+ and "_dbus_interface" in cls.__dict__[method_name].__dict__
+ and cls.__dict__[method_name]._dbus_interface == dbus_interface):
+ # the candidate class has a dbus method on the correct interface,
+ # or overrides a method that is, success!
+ parent_method = cls.__dict__[method_name]
+ sucessful = True
+ break
- else:
- # simpler version of above
- for cls in self.__class__.__mro__:
- if (not candidate and method_name in cls.__dict__):
- candidate = cls
+ else:
+ # simpler version of above
+ for cls in self.__class__.__mro__:
+ if (not candidate_class and method_name in cls.__dict__):
+ candidate_class = cls
- if (candidate and method_name in cls.__dict__
- and "_dbus_is_method" in cls.__dict__[method_name].__dict__):
- target_parent = cls.__dict__[method_name]
- sucessful = True
- break
+ if (candidate_class and method_name in cls.__dict__
+ and "_dbus_is_method" in cls.__dict__[method_name].__dict__):
+ parent_method = cls.__dict__[method_name]
+ sucessful = True
+ break
- retval = candidate.__dict__[method_name](self, *argument_list)
- target_name = str(candidate.__module__) + '.' + candidate.__name__ + '.' + method_name
+ if sucessful:
+ return (candidate_class.__dict__[method_name], parent_method)
+ else:
+ if dbus_interface:
+ raise UnknownMethodException('%s is not a valid method of interface %s' % (method_name, dbus_interface))
+ else:
+ raise UnknownMethodException('%s is not a valid method' % method_name)
- if not sucessful:
- if not dbus_interface:
- raise UnknownMethodException('%s is not a valid method'%(message.get_member()))
- else:
- raise UnknownMethodException('%s is not a valid method of interface %s'%(message.get_member(), dbus_interface))
- except Exception, e:
- if e.__module__ == '__main__':
- # FIXME: is it right to use .__name__ here?
- error_name = e.__class__.__name__
+def _method_reply_return(connection, message, method_name, signature, *retval):
+ reply = dbus_bindings.MethodReturn(message)
+ iter = reply.get_iter(append=True)
+
+ # do strict adding if an output signature was provided
+ if signature:
+ if len(signature) > len(retval):
+ raise TypeError('output signature %s is longer than the number of values returned by %s' %
+ (signature, method_name))
+ elif len(retval) > len(signature):
+ raise TypeError('output signature %s is shorter than the number of values returned by %s' %
+ (signature, method_name))
else:
- error_name = e.__module__ + '.' + str(e.__class__.__name__)
+ for (value, sig) in zip(retval, signature):
+ iter.append_strict(value, sig)
- error_contents = str(e)
- reply = dbus_bindings.Error(message, error_name, error_contents)
+ # no signature, try and guess the return type by inspection
else:
- reply = dbus_bindings.MethodReturn(message)
+ for value in retval:
+ iter.append(value)
- # do strict adding if an output signature was provided
- if target_parent._dbus_out_signature != None:
- # iterate signature into list of complete types
- signature = tuple(dbus_bindings.Signature(target_parent._dbus_out_signature))
+ connection.send(reply)
- if retval == None:
- if len(signature) != 0:
- raise TypeError('%s returned nothing but output signature is %s' %
- (target_name, target_parent._dbus_out_signature))
- elif len(signature) == 1:
- iter = reply.get_iter(append=True)
- iter.append_strict(retval, signature[0])
- elif len(signature) > 1:
- if operator.isSequenceType(retval):
- if len(signature) > len(retval):
- raise TypeError('output signature %s is longer than the number of values returned by %s' %
- (target_parent._dbus_out_signature, target_name))
- elif len(retval) > len(signature):
- raise TypeError('output signature %s is shorter than the number of values returned by %s' %
- (target_parent._dbus_out_signature, target_name))
- else:
- iter = reply.get_iter(append=True)
- for (value, sig) in zip(retval, signature):
- iter.append_strict(value, sig)
- else:
- raise TypeError('output signature %s has multiple values but %s didn\'t return a sequence type' %
- (target_parent._dbus_out_signature, target_name))
- # try and guess the return type
- elif retval != None:
- iter = reply.get_iter(append=True)
- iter.append(retval)
+def _method_reply_error(connection, message, exception):
+ if '_dbus_error_name' in exception.__dict__:
+ name = exception._dbus_error_name
+ elif exception.__module__ == '__main__':
+ name = 'org.freedesktop.DBus.Python.%s' % exception.__class__.__name__
+ else:
+ name = 'org.freedesktop.DBus.Python.%s.%s' % (exception.__module__, exception.__class__.__name__)
+
+ contents = str(exception)
+ reply = dbus_bindings.Error(message, name, contents)
+
+ connection.send(reply)
- return reply
class InterfaceType(type):
def __init__(cls, name, bases, dct):
@@ -251,17 +243,53 @@
def _message_cb(self, connection, message):
try:
- target_method_name = message.get_member()
+ # lookup candidate method and parent method
+ method_name = message.get_member()
+ interface_name = message.get_interface()
+ (candidate_method, parent_method) = _method_lookup(self, method_name, interface_name)
+
+ # call method
args = message.get_args_list()
-
- reply = _dispatch_dbus_method_call(self, args, message)
+ retval = candidate_method(self, *args)
- self._connection.send(reply)
- except Exception, e:
- error_reply = dbus_bindings.Error(message,
- "org.freedesktop.DBus.Python.%s" % e.__class__.__name__,
- str(e))
- self._connection.send(error_reply)
+ # send return reply if it's not an asynchronous function
+ # if we have a signature, use it to turn the return value into a tuple as appropriate
+ if parent_method._dbus_out_signature:
+ # iterate signature into list of complete types
+ signature = tuple(dbus_bindings.Signature(parent_method._dbus_out_signature))
+
+ # if we have zero or one return values we want make a tuple
+ # for the _method_reply_return function, otherwise we need
+ # to check we're passing it a sequence
+ if len(signature) == 0:
+ if retval == None:
+ retval = ()
+ else:
+ raise TypeError('%s has an empty output signature but did not return None' %
+ method_name)
+ elif len(signature) == 1:
+ retval = (retval,)
+ else:
+ if operator.isSequenceType(retval):
+ # multi-value signature, multi-value return... proceed unchanged
+ pass
+ else:
+ raise TypeError('%s has multiple output values in signature %s but did not return a sequence' %
+ (method_name, signature))
+
+ # no signature, so just turn the return into a tuple and send it as normal
+ else:
+ signature = None
+ if retval == None:
+ retval = ()
+ else:
+ retval = (retval,)
+
+ print retval, signature
+ _method_reply_return(connection, message, method_name, signature, *retval)
+ except Exception, exception:
+ # send error reply
+ _method_reply_error(connection, message, exception)
@method('org.freedesktop.DBus.Introspectable', in_signature='', out_signature='s')
def Introspect(self):
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