Argument Type Subclasses

[Lawrence D'Oliveiro]

D-Bus defines separate types for arguments of type “object path”,
“signature” and “Unix FD”, so I thought it made sense to do the same in
my Python binding <https://github.com/ldo/dbussy>. These are subclasses
of string and integer, and the base classes are still acceptable for
those arguments, but the retrieved values are always of the appropriate
subclass:

    import dbussy

    msg = dbussy.Message.new_method_call \
      (
        destination = "com.example",
        path = "/com/example",
        iface = "com.example",
        method = "something"
      ).append_objects("vh", ("s", "stderr"), 2)
    print("path = %s" % repr(msg.path))
    print("args = %s" % repr(msg.all_objects))

produces output

    path = ObjectPath('/com/example')
    args = [(Signature('s'), 'stderr'), UnixFD(4)]