BGE Python API

This changes how the BGE classes and Python work together, which hasnt changed since blender went opensource.
The main difference is PyObjectPlus - the base class for most game engine classes, no longer inherit from PyObject, and cannot be cast to a PyObject.

This has the advantage that the BGE does not have to keep 2 reference counts valid for C++ and Python.

Previously C++ classes would never be freed while python held a reference, however this reference could be problematic eg: a GameObject that isnt in a scene anymore should not be used by python, doing so could even crash blender in some cases.

Instead PyObjectPlus has a member "PyObject *m_proxy" which is lazily initialized when python needs it. m_proxy reference counts are managed by python, though it should never be freed while the C++ class exists since it holds a reference to avoid making and freeing it all the time.
When the C++ class is free'd it sets the m_proxy reference to NULL, If python accesses this variable it will raise a RuntimeError, (check the isValid attribute to see if its valid without raising an error).
- This replaces the m_zombie bool and IsZombie() tests added recently.

In python return values that used to be..
 return value->AddRef();
Are now
 return value->GetProxy();
or...
 return value->NewProxy(true); // true means python owns this C++ value which will be deleted when the PyObject is freed

1 files changed, 3 insertions, 9 deletions

diff --git a/source/gameengine/Ketsji/KX_BlenderMaterial.cpp b/source/gameengine/Ketsji/KX_BlenderMaterial.cpp
index 0e417dde5d2..bdad21f76eb 100644
--- a/source/gameengine/Ketsji/KX_BlenderMaterial.cpp
+++ b/source/gameengine/Ketsji/KX_BlenderMaterial.cpp
@@ -827,8 +827,7 @@ KX_PYMETHODDEF_DOC( KX_BlenderMaterial, getShader , "getShader()")
 			m_flag &= ~RAS_BLENDERGLSL;
 			mMaterial->SetSharedMaterial(true);
 			mScene->GetBucketManager()->ReleaseDisplayLists(this);
-			Py_INCREF(mShader);
-			return mShader;
+			return mShader->GetProxy();
 		}else
 		{
 			// decref all references to the object
@@ -836,13 +835,8 @@ KX_PYMETHODDEF_DOC( KX_BlenderMaterial, getShader , "getShader()")
 			// We will then go back to fixed functionality
 			// for this material
 			if(mShader) {
-				if(mShader->ob_refcnt > 1) {
-					Py_DECREF(mShader);
-				}
-				else {
-					delete mShader;
-					mShader=0;
-				}
+				delete mShader; /* will handle python de-referencing */
+				mShader=0;
 			}
 		}
 		Py_RETURN_NONE;