BGE : Standardization of callbacks execution.

A new function (RunPythonCallBackList) to call all python functions
contained in a python list was developed.

This function has:
  - first argument is the python list of callbacks
  - second argument is a python list of arguments
  - third argument is the minimum quantity of arguments
  - forth argument is the maximum quantity of arguments

It improves flexibility and supports *args.

Reviewers: moguri, dfelinto, campbellbarton, sybren

Reviewed By: campbellbarton, sybren

Subscribers: sybren

Projects: #game_engine

Differential Revision: https://developer.blender.org/D1102

source/gameengine/Expressions/KX_PythonCallBack.cpp

@@ -0,0 +1,116 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Porteries Tristan.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file gameengine/Expressions/KX_PythonCallBack.cpp
+ *  \ingroup expressions
+ */
+
+#include "KX_PythonCallBack.h"
+#include <iostream>
+#include <stdarg.h>
+
+/** Check if a python value is a function and have the correct number of arguments.
+ * \param value The python value to check.
+ * \param minargcount The minimum of arguments possible.
+ * \param maxargcount The maximum of arguments possible.
+ * \param r_argcount The number of argument of this function, this variable will be
+ * changed in the function.
+ */
+static PyObject *CheckPythonFunction(PyObject *value, unsigned int minargcount, unsigned int maxargcount, unsigned int &r_argcount)
+{
+	if (PyMethod_Check(value)) {
+		PyCodeObject *code = ((PyCodeObject *)PyFunction_GET_CODE(PyMethod_GET_FUNCTION(value)));
+		// *args support
+		r_argcount = (code->co_flags & CO_VARARGS) ? maxargcount : (code->co_argcount - 1);
+	}
+	else if (PyFunction_Check(value)) {
+		PyCodeObject *code = ((PyCodeObject *)PyFunction_GET_CODE(value));
+		// *args support
+		r_argcount = (code->co_flags & CO_VARARGS) ? maxargcount : code->co_argcount;
+	}
+	else { // is not a methode or a function
+		PyErr_Format(PyExc_TypeError, "items must be functions or methodes, not %s",
+					 Py_TYPE(value)->tp_name);
+		return NULL;
+	}
+
+	if (r_argcount < minargcount || r_argcount >  maxargcount) {
+		// wrong number of arguments
+		PyErr_Format(PyExc_TypeError, "methode or function (%s) has invalid number of arguments (%i) must be between %i and %i",
+					 Py_TYPE(value)->tp_name, r_argcount, minargcount, maxargcount);
+		return NULL;
+	}
+
+	return value;
+}
+
+/** Create a python tuple to call a python function
+ * \param argcount The lenght of the tuple.
+ * \param arglist The fully list of python arguments [size >= argcount].
+ */
+static PyObject *CreatePythonTuple(unsigned int argcount, PyObject **arglist)
+{
+	PyObject *tuple = PyTuple_New(argcount);
+
+	for (unsigned int i = 0; i < argcount; ++i) {
+		PyObject *item = arglist[i];
+		// increment reference and copy it in a new tuple
+		Py_INCREF(item);
+		PyTuple_SET_ITEM(tuple, i, item);
+	}
+
+	return tuple;
+}
+
+void RunPythonCallBackList(PyObject *functionlist, PyObject **arglist, unsigned int minargcount, unsigned int maxargcount)
+{
+	unsigned int size = PyList_Size(functionlist);
+	PyObject *argTuples[(maxargcount - minargcount) + 1] = {NULL};
+
+	for (unsigned int i = 0; i < size; ++i) {
+		unsigned int funcargcount = 0;
+
+		PyObject *item = PyList_GET_ITEM(functionlist, i);
+		PyObject *func = CheckPythonFunction(item, minargcount, maxargcount, funcargcount);
+		if (!func) { // this item fails the check
+			PyErr_Print();
+			PyErr_Clear();
+			continue;
+		}
+
+		// get correct argument tuple.
+		PyObject *tuple = argTuples[funcargcount - minargcount];
+		if (!tuple)
+			argTuples[funcargcount - minargcount] = tuple = CreatePythonTuple(funcargcount, arglist);
+
+		PyObject *ret = PyObject_Call(func, tuple, NULL);
+		if (!ret) { // if ret is NULL this seems that the function doesn't work !
+			PyErr_Print();
+			PyErr_Clear();
+		}
+		else
+			Py_DECREF(ret);
+	}
+
+	for (unsigned int i = 0; i <= (maxargcount - minargcount); ++i)
+		Py_XDECREF(argTuples[i]);
+}