cleaning + comments, and add the nondynamic feature handlers

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@6266 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Lib/python/pyuserdir.swg

@@ -0,0 +1,56 @@
+/* -----------------------------------------------------------------------------
+ *  Special user directives
+ * ----------------------------------------------------------------------------- */
+
+/* shadow code */
+#define %shadow      %insert("shadow")
+#define %pythoncode  %insert("python")
+
+
+/* 
+Use the "nondynamic" feature to make a wrapped class behaves as a "nondynamic"
+one, ie, a python class that doesn't dynamically add new attributes.
+
+For example, for the class
+
+%pythonnondynamic(1) A;
+struct A
+{
+  int a;
+  int b;
+};
+
+you will get:
+
+ aa = A()
+ aa.a = 1  # Ok
+ aa.b = 1  # Ok
+ aa.c = 3  # error
+
+Since "nondynamic" is a feature, if you use it like
+
+%pythonnondynamic(1);
+
+it will make all the wrapped classes nondynamic ones.
+
+The implementation is based on the recipe:
+
+ http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/252158
+
+and works for modern (-modern) and plain python. We don't use __slots__, 
+so, it works with old python versions. 
+
+You can also use the raw %feature form
+
+%feature("pythonnondynamic") A;
+
+or the inverse form
+
+%pythondynamic(0) A;
+
+
+*/
+
+
+#define %pythonnondynamic(FLAG) %feature("python:nondynamic", #FLAG)
+#define %pythondynamic(FLAG) %pythonnondynamic(!FLAG)