What are the consequences of adding a subtype?

Currently functions have two subtypes: normal ones (0) and builtin functions (USHRT_MAX). What would be the implications of adding two more?

I propose adding FUNCTION_GENERATOR and FUNCTION_GENSTATE to differentiate continue functions, and the state functions that they return; and also a Pike-callable Function.function_type which will return the corresponding type. Thus:

continue int demo() { }

Function.function_type(demo) == 1 Function.function_type(demo()) == 2

Alternatively, if this doesn't need to be a subtype, is there a way to recognize them already? I'm poking around, trying to implement this, but I think more information needs to be carried through to runtime - might be wrong though.

ChrisA