If speed of class creation is important (as it is for us). suggest to call type directly rather then evaluating a string every time and executing it - this is one way.

	/* always use O not N when calling, N causes refcount errors */
	newclass = PyObject_CallFunction((PyObject *)&PyType_Type, (char

*)"s(O) {sss()}", idname, py_base_class, "__module__", "bpy.types", "__slots__");

which is like doing this in python...

type(idname, (py_base_class, ), dict(__module__="bpy.types", __slots__=()))

On Thu, May 10, 2012 at 6:17 PM, Mateusz Loskot mateusz@loskot.net wrote:

On 10 May 2012 14:55, Mateusz Loskot mateusz@loskot.net wrote:

...

On 10 May 2012 14:01, Stefan Behnel python_capi@behnel.de wrote:

...

You can execute any Python code from your C code. Look for the PyRun_*() functions.

Do you mean something similar to this approach?

 /* dynamically generated lengthy class definition */ const char* c = "class A(object): pass";

PyObject* class_a = PyRun_StringFlags(c, ...); PyObject_SetAttrString(module, "A", class_a)

The pseudo-code above is incorrect. I have come up with the following example of dynamically generating new Python class, indirectly through script using class keyword. Such dynamically created class is added to module dictionary:

/* error checks removed for brevity */

static PyModuleDef embmodule = { ... };

PyInit_emb(void) { PyObject* m = PyModule_Create(&embmodule); PyObject* d = PyModule_GetDict(m);

   /* Required to allow 'class' use in context of module which is not yet complete and ready. Otherwise, error is thrown: ImportError: __build_class__ not found */ PyObject* builtins = PyEval_GetBuiltins(); PyDict_SetItemString(d, "__builtins__", builtins);

   /* Python class is dynamically generated */ const char* c = "class A(object):\n\tpass"; /* sample class */

   /* Create object for A class, automatically added to the module dictionary as noddy.A */ PyRun_StringFlags(c, Py_file_input, d, d, NULL);

   return m; }

This approach works well. If anyone noticed a problem or there is better way to do the same, please let me know.

Best regards,

Mateusz Loskot, http://mateusz.loskot.net

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