def getClassAlias(self, klass):
        """
        Gets a class alias based on the supplied C{klass}. If one is not found
        in the global context, one is created locally.

        If you supply a string alias and the class is not registered,
        L{pyamf.UnknownClassAlias} will be raised.

        @param klass: A class object or string alias.
        @return: The L{pyamf.ClassAlias} instance that describes C{klass}
        """
        try:
            return self._class_aliases[klass]
        except KeyError:
            pass

        try:
            alias = self._class_aliases[klass] = pyamf.get_class_alias(klass)
        except pyamf.UnknownClassAlias:
            if isinstance(klass, python.str_types):
                raise

            # no alias has been found yet .. check subclasses
            alias = util.get_class_alias(klass) or pyamf.ClassAlias
            meta = util.get_class_meta(klass)
            alias = alias(klass, defer=True, **meta)

            self._class_aliases[klass] = alias

        return alias

    def test_simple(self):
        class A(object):
            pass

        pyamf.register_alias_type(DummyAlias, A)

        self.assertEqual(util.get_class_alias(A), DummyAlias)

def register_class(klass, alias=None):
    """
    Registers a class to be used in the data streaming. This is the equivalent
    of the C{[RemoteClass(alias="foobar")]} metatag in Adobe Flex, and the
    C{flash.net.registerClassAlias} method in Actionscript 3.0.

    @return: The registered L{ClassAlias} instance.
    @see: L{unregister_class}
    @see: U{flash.net.registerClassAlias on Adobe Help (external)
            <http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/package.html#registerClassAlias%28%29>}
    """
    meta = util.get_class_meta(klass)

    if alias is not None:
        meta["alias"] = alias

    alias_klass = util.get_class_alias(klass) or ClassAlias

    x = alias_klass(klass, defer=True, **meta)

    if not x.anonymous:
        CLASS_CACHE[x.alias] = x

    CLASS_CACHE[klass] = x

    return x

    def test_multiple(self):
        class A(object):
            pass

        class B(object):
            pass

        class C(object):
            pass

        pyamf.register_alias_type(DummyAlias, A)
        pyamf.register_alias_type(AnotherDummyAlias, B)
        pyamf.register_alias_type(YADummyAlias, C)

        self.assertEqual(util.get_class_alias(B), AnotherDummyAlias)
        self.assertEqual(util.get_class_alias(C), YADummyAlias)
        self.assertEqual(util.get_class_alias(A), DummyAlias)

    def test_subclass(self):
        class A(object):
            pass

        class B(A):
            pass

        pyamf.register_alias_type(DummyAlias, A)

        self.assertEquals(util.get_class_alias(B), DummyAlias)

    def test_nested(self):
        class A(object):
            pass

        class B(object):
            pass

        class C(object):
            pass

        pyamf.register_alias_type(DummyAlias, A, B, C)

        self.assertEqual(util.get_class_alias(B), DummyAlias)

    def getClassAlias(self, klass):
        """
        Gets a class alias based on the supplied C{klass}.
        """
        if klass not in self.class_aliases.keys():
            try:
                self.class_aliases[klass] = get_class_alias(klass)
            except UnknownClassAlias:
                # no alias has been found yet .. check subclasses
                alias = util.get_class_alias(klass)

                if alias is not None:
                    self.class_aliases[klass] = alias(klass, None)
                else:
                    self.class_aliases[klass] = None

        return self.class_aliases[klass]

    def getClassAlias(self, klass):
        """
        Gets a class alias based on the supplied C{klass}.
        """
        try:
            return self.class_aliases[klass]
        except KeyError:
            pass

        try:
            self.class_aliases[klass] = get_class_alias(klass)
        except UnknownClassAlias:
            # no alias has been found yet .. check subclasses
            alias = util.get_class_alias(klass)

            self.class_aliases[klass] = alias(klass)

        return self.class_aliases[klass]

    def getClassAlias(self, klass):
        """
        Gets a class alias based on the supplied C{klass}.

        @param klass: The class object.
        @return: The L{ClassAlias} that is linked to C{klass}
        """
        try:
            return self.class_aliases[klass]
        except KeyError:
            pass

        try:
            self.class_aliases[klass] = get_class_alias(klass)
        except UnknownClassAlias:
            # no alias has been found yet .. check subclasses
            alias = util.get_class_alias(klass)

            self.class_aliases[klass] = alias(klass)

        return self.class_aliases[klass]

def register_class(klass, alias=None):
    """
    Registers a class to be used in the data streaming.

    @return: The registered L{ClassAlias}.
    """
    meta = util.get_class_meta(klass)

    if alias is not None:
        meta['alias'] = alias

    alias_klass = util.get_class_alias(klass)

    x = alias_klass(klass, defer=True, **meta)

    if not x.anonymous:
        CLASS_CACHE[x.alias] = x

    CLASS_CACHE[klass] = x

    return x

def register_class(klass, alias=None, attrs=None, attr_func=None, metadata=[]):
    """
    Registers a class to be used in the data streaming.

    @type alias: C{str}
    @param alias: The alias of klass, i.e. C{org.example.Person}.
    @param attrs: A list of attributes that will be encoded for the class.
    @type attrs: C{list} or C{None}
    @type attr_func:
    @param attr_func:
    @type metadata:
    @param metadata:
    @raise TypeError: PyAMF doesn't support required init arguments.
    @raise TypeError: The C{klass} is not callable.
    @raise ValueError: The C{klass} or C{alias} is already registered.
    @return: The registered L{ClassAlias}.
    """
    if not callable(klass):
        raise TypeError("klass must be callable")

    if klass in CLASS_CACHE:
        raise ValueError("klass %s already registered" % (klass,))

    if alias is not None and alias in CLASS_CACHE.keys():
        raise ValueError("alias '%s' already registered" % (alias,))

    alias_klass = util.get_class_alias(klass)

    if alias_klass is None:
        alias_klass = ClassAlias

    x = alias_klass(klass, alias, attr_func=attr_func,
        attrs=attrs, metadata=metadata)

    if alias is None:
        alias = "%s.%s" % (klass.__module__, klass.__name__,)

    CLASS_CACHE[alias] = x

    return x

 def test_none_existant(self):
     self.assertEqual(util.get_class_alias(self.__class__), None)

 def test_none_existant(self):
     self.assertEquals(pyamf.ClassAlias, util.get_class_alias(self.__class__))

    def writeObject(self, obj, use_proxies=None):
        """
        Writes an object to the stream.

        @param obj: The object data to be encoded to the AMF3 data stream.
        @type obj: object data
        @raise EncodeError: Encoding an object in amf3 tagged as amf0 only.
        """
        if use_proxies is None:
            use_proxies = self.use_proxies

        if use_proxies is True:
            self.writeProxy(obj)

            return

        self.stream.write(TYPE_OBJECT)

        ref = self.context.getObjectReference(obj)

        if ref is not None:
            self._writeInteger(ref << 1)

            return

        self.context.addObject(obj)

        # object is not referenced, serialise it
        kls = obj.__class__
        definition = self.context.getClass(kls)
        alias = None
        class_ref = False # if the class definition is a reference

        if definition:
            class_ref = True
            alias = definition.alias

            if alias.anonymous and definition.reference is not None:
                class_ref = True
        else:
            try:
                alias = pyamf.get_class_alias(kls)
            except pyamf.UnknownClassAlias:
                alias_klass = util.get_class_alias(kls)
                meta = util.get_class_meta(kls)

                alias = alias_klass(kls, defer=True, **meta)

            definition = ClassDefinition(alias)

            self.context.addClass(definition, alias.klass)

        if class_ref:
            self.stream.write(definition.reference)
        else:
            ref = 0

            if definition.encoding != ObjectEncoding.EXTERNAL:
                ref += definition.attr_len << 4

            final_reference = encode_int(ref | definition.encoding << 2 |
                REFERENCE_BIT << 1 | REFERENCE_BIT)

            self.stream.write(final_reference)

            definition.reference = encode_int(
                definition.reference << 2 | REFERENCE_BIT)

            if alias.anonymous:
                self.stream.write_uchar(0x01)
            else:
                self._writeString(alias.alias)

            # work out what the final reference for the class will be.
            # this is okay because the next time an object of the same
            # class is encoded, class_ref will be True and never get here
            # again.

        if alias.external:
            obj.__writeamf__(DataOutput(self))

            return

        attrs = alias.getEncodableAttributes(obj, codec=self)

        if alias.static_attrs:
            if not class_ref:
                [self._writeString(attr) for attr in alias.static_attrs]

            for attr in alias.static_attrs:
                value = attrs.pop(attr)

                self.writeElement(value)

            if definition.encoding == ObjectEncoding.STATIC:
                return

        if definition.encoding == ObjectEncoding.DYNAMIC:
            if attrs:
                for attr, value in attrs.iteritems():
#.........这里部分代码省略.........