-

cool-RR · cool-RR · commit 6dc9eac2cb89 · 2014-01-24T17:44:49.000+02:00
diff --git a/source_py3/python_toolbox/monkeypatching_tools.py b/source_py3/python_toolbox/monkeypatching_tools.py
@@ -116,6 +116,13 @@ def change_defaults_(function_, new_defaults_):
              double=True, 
          )
         
+        non_existing_arguments = set(new_defaults) - set(defaultful_parameters)
+        if non_existing_arguments:
+            raise Exception("Arguments %s are not defined, or do not have a "
+                            "default defined. (Can't create default value for "
+                            "argument that has no existing default.)"
+                            % non_existing_arguments)
+        
         for parameter_name in keyword_only_defaultful_parameters:
             if parameter_name in new_defaults_:
                 kwdefaults[parameter_name] = new_defaults_[parameter_name]
diff --git a/source_py3/test_python_toolbox/test_monkeypatching_tools/test_change_defaults.py b/source_py3/test_python_toolbox/test_monkeypatching_tools/test_change_defaults.py
@@ -23,4 +23,17 @@ def f2(alpha, beta, *args, gamma=10, delta=20, **kwargs):
     def f3(alpha, beta, *args, gamma=10, delta=20, **kwargs):
         return (alpha, beta, args, gamma, delta, kwargs)
     assert f3(1, 2) == (1, 2, (), 1000, 20, {})
+    
+    @monkeypatching_tools.change_defaults(new_defaults={'x': 'A', 'z': 'C'})
+    def f4(x='a', y='b', z='c'):
+        return (x, y, z)
+    assert f4() == ('A', 'b', 'C')
+    
+    with cute_testing.RaiseAssertor(Exception):
+        @monkeypatching_tools.change_defaults(new_defaults={'x': 'A', 'z': 'C',
+                                                            'nonexistant': 7,})
+        def f5(x='a', y='b', z='c'):
+            return (x, y, z)
+    
+    
         
