Implement Korlib API versioning

A common error when developing with Korman and Korlib is to forget to
recompile _korlib on changes in the upstream C++ code. This will prevent
the errors from being catastrophic and will revert the user to the
python reference implementation with a minimum of fuss.

korlib/module.cpp

@@ -18,6 +18,9 @@
 #include "sound.h"
 #include "texture.h"
 
+// This konstant is compared against that in the Python module to prevent sneaky errors...
+#define KORLIB_API_VERSION 1
+
 extern "C" {
 
 static PyMethodDef korlib_Methods[] = {
@@ -46,6 +49,9 @@ PyMODINIT_FUNC PyInit__korlib() {
     // Module classes...
     PyModule_AddObject(module, "GLTexture", Init_pyGLTexture_Type());
 
+    // Konstants
+    PyModule_AddIntConstant(module, "_KORLIB_API_VERSION", KORLIB_API_VERSION);
+
     return module;
 }
 

korman/korlib/__init__.py

@@ -13,11 +13,22 @@
 #    You should have received a copy of the GNU General Public License
 #    along with Korman.  If not, see <http://www.gnu.org/licenses/>.
 
+_KORLIB_API_VERSION = 1
+
 try:
-    from _korlib import *
+    from _korlib import _KORLIB_API_VERSION as _C_API_VERSION
-except ImportError:
+    if _KORLIB_API_VERSION != _C_API_VERSION:
+        raise ImportError()
+
+except ImportError as ex:
     from .texture import *
 
+    if "_C_API_VERSION" in locals():
+        msg = "Korlib C Module Version mismatch (expected {}, got {}).".format(_KORLIB_API_VERSION, _C_API_VERSION)
+    else:
+        msg = "Korlib C Module did not load correctly."
+    print(msg, "Using PyKorlib :(", sep=' ')
+
     def create_bump_LUT(mipmap):
         kLUTHeight = 16
         kLUTWidth = 16
@@ -57,11 +68,9 @@ except ImportError:
     def inspect_voribsfile(stream, header):
         raise NotImplementedError("Ogg Vorbis not supported unless _korlib is compiled")
 
-    def is_c_library():
-        return False
 else:
-    def is_c_library():
+    from _korlib import *
-        return True
+
 finally:
     from .console import ConsoleToggler
     from .texture import TEX_DETAIL_ALPHA, TEX_DETAIL_ADD, TEX_DETAIL_MULTIPLY