Added to/from_python converters for [plain] char.

Reverted to original converters for un/signed char.


[SVN r9046]

example/passing_char.cpp

@@ -0,0 +1,52 @@
+#include <iostream>
+
+namespace { // Avoid cluttering the global namespace.
+
+  // In C++, char, signed char and unsigned char are three distinct types.
+  // The Boost Python Library maps signed & unsigned char to
+  // Python integers. Plain char is mapped to a Python string with
+  // exactly one character.
+
+  // Plain char.
+  char get_char() { return 'ÿ'; }
+  void use_char(char c) {
+    std::cout << c << std::endl;
+  }
+
+  // signed char.
+  signed char get_signed_char() { return -128; }
+  void use_signed_char(signed char c) {
+    std::cout << c << " " << static_cast<int>(c) << std::endl;
+  }
+
+  // unsigned char.
+  unsigned char get_unsigned_char() { return 128; }
+  void use_unsigned_char(unsigned char c) {
+    std::cout << c << " " << static_cast<unsigned int>(c) << std::endl;
+  }
+}
+
+#include <boost/python/class_builder.hpp>
+namespace python = boost::python;
+
+extern "C"
+DL_EXPORT(void)
+initpassing_char()
+{
+  try
+  {
+    // Create an object representing this extension module.
+    python::module_builder this_module("passing_char");
+
+    this_module.def(get_char, "get_char");
+    this_module.def(use_char, "use_char");
+    this_module.def(get_signed_char, "get_signed_char");
+    this_module.def(use_signed_char, "use_signed_char");
+    this_module.def(get_unsigned_char, "get_unsigned_char");
+    this_module.def(use_unsigned_char, "use_unsigned_char");
+  }
+  catch(...)
+  {
+    python::handle_exception(); // Deal with the exception for Python
+  }
+}