Attachment 35713 Details for Bug 26903 – Implementation of D-Bus properties

Implementation of D-Bus properties

dbus-properties.py (text/x-python), 7.82 KB, created by Anonymous Helper on 2010-05-17 11:56:43 UTC

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Creator: Anonymous Helper

Created: 2010-05-17 11:56:43 UTC

Size: 7.82 KB

patch

obsolete

>#!/usr/bin/python
># -*- mode: python; coding: utf-8 -*-
>
>import xml.dom.minidom
>import inspect
>
>import dbus
>import dbus.service
>
>def dbus_service_property(dbus_interface, signature=u"v",
>                          access=u"readwrite", byte_arrays=False):
>    """Decorators for marking methods of a DBusObjectWithProperties to
>    become properties on the D-Bus.
>    
>    The decorated method will be called with no arguments by "Get"
>    and with one argument by "Set".
>    
>    The parameters, where they are supported, are the same as
>    dbus.service.method, except there is only "signature", since the
>    type from Get() and the type sent to Set() is the same.
>    """
>    # Encoding deeply encoded byte arrays is not supported yet by the
>    # "Set" method, so we fail early here:
>    if byte_arrays and signature != u"ay":
>        raise ValueError(u"Byte arrays not supported for non-'ay'"
>                         u" signature %r" % signature)
>    def decorator(func):
>        func._dbus_is_property = True
>        func._dbus_interface = dbus_interface
>        func._dbus_signature = signature
>        func._dbus_access = access
>        func._dbus_name = func.__name__
>        if func._dbus_name.endswith(u"_dbus_property"):
>            func._dbus_name = func._dbus_name[:-14]
>        func._dbus_get_args_options = {u'byte_arrays': byte_arrays }
>        return func
>    return decorator
>
>
>class DBusPropertyException(dbus.exceptions.DBusException):
>    """A base class for D-Bus property-related exceptions
>    """
>    def __unicode__(self):
>        return unicode(str(self))
>
>
>class DBusPropertyAccessException(DBusPropertyException):
>    """A property's access permissions disallows an operation.
>    """
>    pass
>
>
>class DBusPropertyNotFound(DBusPropertyException):
>    """An attempt was made to access a non-existing property.
>    """
>    pass
>
>
>class DBusObjectWithProperties(dbus.service.Object):
>    """A D-Bus object with properties.
>
>    Classes inheriting from this can use the dbus_service_property
>    decorator to expose methods as D-Bus properties.  It exposes the
>    standard Get(), Set(), and GetAll() methods on the D-Bus.
>    """
>    
>    @staticmethod
>    def _is_dbus_property(obj):
>        return getattr(obj, u"_dbus_is_property", False)
>    
>    def _get_all_dbus_properties(self):
>        """Returns a generator of (name, attribute) pairs
>        """
>        return ((prop._dbus_name, prop)
>                for name, prop in
>                inspect.getmembers(self, self._is_dbus_property))
>    
>    def _get_dbus_property(self, interface_name, property_name):
>        """Returns a bound method if one exists which is a D-Bus
>        property with the specified name and interface.
>        """
>        for name in (property_name,
>                     property_name + u"_dbus_property"):
>            prop = getattr(self, name, None)
>            if (prop is None
>                or not self._is_dbus_property(prop)
>                or prop._dbus_name != property_name
>                or (interface_name and prop._dbus_interface
>                    and interface_name != prop._dbus_interface)):
>                continue
>            return prop
>        # No such property
>        raise DBusPropertyNotFound(self.dbus_object_path + u":"
>                                   + interface_name + u"."
>                                   + property_name)
>    
>    @dbus.service.method(dbus.PROPERTIES_IFACE, in_signature=u"ss",
>                         out_signature=u"v")
>    def Get(self, interface_name, property_name):
>        """Standard D-Bus property Get() method, see D-Bus standard.
>        """
>        prop = self._get_dbus_property(interface_name, property_name)
>        if prop._dbus_access == u"write":
>            raise DBusPropertyAccessException(property_name)
>        value = prop()
>        if not hasattr(value, u"variant_level"):
>            return value
>        return type(value)(value, variant_level=value.variant_level+1)
>    
>    @dbus.service.method(dbus.PROPERTIES_IFACE, in_signature=u"ssv")
>    def Set(self, interface_name, property_name, value):
>        """Standard D-Bus property Set() method, see D-Bus standard.
>        """
>        prop = self._get_dbus_property(interface_name, property_name)
>        if prop._dbus_access == u"read":
>            raise DBusPropertyAccessException(property_name)
>        if prop._dbus_get_args_options[u"byte_arrays"]:
>            # The byte_arrays option is not supported yet on
>            # signatures other than "ay".
>            if prop._dbus_signature != u"ay":
>                raise ValueError
>            value = dbus.ByteArray(''.join(unichr(byte)
>                                           for byte in value))
>        prop(value)
>    
>    @dbus.service.method(dbus.PROPERTIES_IFACE, in_signature=u"s",
>                         out_signature=u"a{sv}")
>    def GetAll(self, interface_name):
>        """Standard D-Bus property GetAll() method, see D-Bus
>        standard.
>
>        Note: Will not include properties with access="write".
>        """
>        all = {}
>        for name, prop in self._get_all_dbus_properties():
>            if (interface_name
>                and interface_name != prop._dbus_interface):
>                # Interface non-empty but did not match
>                continue
>            # Ignore write-only properties
>            if prop._dbus_access == u"write":
>                continue
>            value = prop()
>            if not hasattr(value, u"variant_level"):
>                all[name] = value
>                continue
>            all[name] = type(value)(value, variant_level=
>                                    value.variant_level+1)
>        return dbus.Dictionary(all, signature=u"sv")
>    
>    @dbus.service.method(dbus.INTROSPECTABLE_IFACE,
>                         out_signature=u"s",
>                         path_keyword='object_path',
>                         connection_keyword='connection')
>    def Introspect(self, object_path, connection):
>        """Standard D-Bus method, overloaded to insert property tags.
>        """
>        xmlstring = dbus.service.Object.Introspect(self, object_path,
>                                                   connection)
>        try:
>            document = xml.dom.minidom.parseString(xmlstring)
>            def make_tag(document, name, prop):
>                e = document.createElement(u"property")
>                e.setAttribute(u"name", name)
>                e.setAttribute(u"type", prop._dbus_signature)
>                e.setAttribute(u"access", prop._dbus_access)
>                return e
>            for if_tag in document.getElementsByTagName(u"interface"):
>                for tag in (make_tag(document, name, prop)
>                            for name, prop
>                            in self._get_all_dbus_properties()
>                            if prop._dbus_interface
>                            == if_tag.getAttribute(u"name")):
>                    if_tag.appendChild(tag)
>                # Add the names to the return values for the
>                # "org.freedesktop.DBus.Properties" methods
>                if (if_tag.getAttribute(u"name")
>                    == u"org.freedesktop.DBus.Properties"):
>                    for cn in if_tag.getElementsByTagName(u"method"):
>                        if cn.getAttribute(u"name") == u"Get":
>                            for arg in cn.getElementsByTagName(u"arg"):
>                                if (arg.getAttribute(u"direction")
>                                    == u"out"):
>                                    arg.setAttribute(u"name", u"value")
>                        elif cn.getAttribute(u"name") == u"GetAll":
>                            for arg in cn.getElementsByTagName(u"arg"):
>                                if (arg.getAttribute(u"direction")
>                                    == u"out"):
>                                    arg.setAttribute(u"name", u"props")
>            xmlstring = document.toxml(u"utf-8")
>            document.unlink()
>        return xmlstring

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Attachments on bug 26903: 35713 | 48084 | 48183 | 98993 | 112098

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