On Sun, Feb 04, 2001 at 11:47:26PM -0500, Guido van Rossum wrote:
Yes, I've often thought that we should be able to heal the split for 95% by using a few well-aimed tricks like this. Later...
I was playing around this weekend with the class/type problem. Without too much effort I had an interpreter that could to things like this: >>> class MyInt(type(1)): ... pass ... >>> i = MyInt(10) >>> i 10 >>> i + 1 11 The major changes were allowing PyClassObject to subclass types (ie. changing PyClass_Check(op) to (PyClass_Check(op) || PyType_Check(op))), writing a _PyType_Lookup function, and making class_lookup use it. The experiment has convinced me that we can allow subclasses of types quite easily without major changes. It has also given me some ideas on "the right way" to solve this problem. The rough scheme I can up yesterday goes like this: PyObject { int ob_refcnt; PyClass ob_class; } PyClass { PyObject_HEAD char *cl_name; getattrfunc cl_getattr; PyMethodTable *cl_methods; } PyMethodTable { binaryfunc nb_add; binaryfunc nb_sub; ... } When calling a method on a object the interpreter would first check for a direct method and if that does not exist then call cl_getattr. Obviously there are still a few details to be worked out. :-) Neil