Handling Structured Types

ues of the correct type before hand. A service may also override the default decoders for extended types such as the date and time types if desired.

The encoding mechanism for data does not provide a way of adding support for your own structured types, whereby the type of that object can also be transmitted. All objects need to be able to be con- verted into instances of scalar types, dictionaries, tuples or lists. To avoid having to do this conversion manually, it is however possible to define an encoder for a structured type which will do this for you.

At the global level, such a function is again registered using the "encoder()" function. The differ- ence between this function and that for scalar types however, is that instead of returning a string giving the name of the scalar type, the value None should be returned in its place. The second value in the tuple should then be the instance of the structured type translated into either a scalar type, dictionary, tuple or list.

def _encode_UserList(object): return (None,list(object))

netsvc.encoder(UserList.UserList,_encode_UserList)

Having returned the translated value, it will be represented to the encoder. Thus it is only necessary to translate the top level of the data structure as enclosed values will in turn be translated automatically if required and if an encoder is registered. This mechanism may also be used in an encoder specific to a service.