Add in an example/test for Python __pow__

- A test for the ternaryfunc builtin slot
- Example of how to wrap C++ class for Python's pow

Examples/test-suite/python/python_builtin_runme.py

@@ -83,6 +83,7 @@ if is_python_builtin():
   if MyClass.less_than_counts != 6:
     raise RuntimeError("python:compare feature not working")
 
+# Test 6
 sa = SimpleArray(5)
 elements = [x for x in sa]
 if elements != [0, 10, 20, 30, 40]:
@@ -96,3 +97,17 @@ subslice = sa[1:3]
 elements = [x for x in subslice]
 if elements != [10, 20]:
   raise RuntimeError("slice not working")
+
+# Test 7 mapping to Python's pow
+x = ANumber(2)
+y = ANumber(4)
+z = x ** y
+if z.Value() != 16:
+  raise RuntimeError("x ** y wrong")
+z = pow(x, y)
+if z.Value() != 16:
+  raise RuntimeError("pow(x, y) wrong")
+z = ANumber(9)
+z = pow(x, y, z)
+if z.Value() != 7:
+  raise RuntimeError("pow(x, y, z) wrong")

Examples/test-suite/python_builtin.i

@@ -226,3 +226,22 @@ void Dealloc2Destroyer(PyObject *v) {
   };
 %}
 
+// Test 7 mapping to Python's pow
+%pybinoperator(__pow__, ANumber::power, ternaryfunc, nb_power);
+
+%inline %{
+class ANumber {
+  int num;
+public:
+  ANumber(int d = 0) : num(d) {}
+  ANumber __pow__(const ANumber &other, const ANumber *x) const {
+    int val = (int)pow(num, other.num);
+    val = x ? val % x->num : val;
+    return ANumber(val);
+  }
+  int Value() const {
+    return num;
+  }
+};
+%}
+