===Python API===

Something to try making import/export script writers happy; Mesh.New() will
not create a new Blender mesh datablock unless the mesh is linked to an
object.

source/blender/python/api2_2x/Mesh.c

@@ -6907,6 +6907,12 @@ static int Mesh_setActiveGroup( BPy_Mesh * self, PyObject * arg )
 
 static void Mesh_dealloc( BPy_Mesh * self )
 {
+	Mesh *mesh = self->mesh;
+
+	/* if the mesh is new and has no users, delete it */
+	if( self->new && !mesh->id.us )
+	    free_libblock( &G.main->mesh, mesh );
+
 	PyObject_DEL( self );
 }
 
@@ -7149,6 +7155,7 @@ static PyObject *M_Mesh_New( PyObject * self_unused, PyObject * args )
 
 	obj->mesh = mesh;
 	obj->object = NULL;
+	obj->new = 1;
 	return (PyObject *)obj;
 }
 
@@ -7403,6 +7410,7 @@ PyObject *Mesh_CreatePyObject( Mesh * me, Object *obj )
 
 	nmesh->mesh = me;
 	nmesh->object = obj;
+	nmesh->new = 0;
 
 	return ( PyObject * ) nmesh;
 }

source/blender/python/api2_2x/Mesh.h

@@ -115,6 +115,7 @@ typedef struct {
 	PyObject_HEAD		/* required python macro   */
 	Mesh *mesh;
 	Object *object;
+	char new;			/* was mesh created or already existed? */
 } BPy_Mesh;
 
 /* PROTOS */

source/blender/python/api2_2x/doc/Mesh.py

@@ -132,6 +132,8 @@ def New(name='Mesh'):
   @param name: The name of the mesh data object.
   @rtype: Mesh
   @return: a new Blender mesh.
+  @note: if the mesh is not linked to an object, its datablock will be deleted
+  when the object is deallocated.
   """
 
 def Mode(mode=0):