Add const to several API functions that take char *. In C++, it's an error to pass a string literal to a char* function without a const_cast(). Rather than require every C++ extension module to put a cast around string literals, fix the API to state the const-ness. I focused on parts of the API where people usually pass literals: PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type slots, etc. Predictably, there were a large set of functions that needed to be fixed as a result of these changes. The most pervasive change was to make the keyword args list passed to PyArg_ParseTupleAndKewords() to be a const char *kwlist[]. One cast was required as a result of the changes: A type object mallocs the memory for its tp_doc slot and later frees it. PyTypeObject says that tp_doc is const char *; but if the type was created by type_new(), we know it is safe to cast to char *.

--- a/Include/cStringIO.h	Sat Dec 10 17:44:27 2005 +0000
+++ b/Include/cStringIO.h	Sat Dec 10 18:50:16 2005 +0000
@@ -38,7 +38,7 @@
   int(*creadline)(PyObject *, char **);
 
   /* Write a string to an output object*/
-  int(*cwrite)(PyObject *, char *, int);
+  int(*cwrite)(PyObject *, const char *, int);
 
   /* Get the output object as a Python string (returns new reference). */
   PyObject *(*cgetvalue)(PyObject *);