C# exception handling improvements - they are robust and don't leak anymore. Requires typemap modifications using attribute canthrow in any unmanaged code typemaps that throw an exception and excode attribute in csout and csconstruct typemaps.

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@6934 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Lib/csharp/csharphead.swg

@@ -122,6 +122,41 @@ DllExport void SWIGSTDCALL SWIGRegisterExceptionCallbacks_$module(SWIG_CSharpExc
   }
 
   static SWIGExceptionHelper exceptionHelper = new SWIGExceptionHelper();
+
+  [ThreadStatic]
+  private static Exception pendingException = null;
+  private static int numExceptionsPending = 0;
+
+  public static bool ExceptionPending {
+    get {
+      bool pending = false;
+      if (numExceptionsPending > 0)
+        if (pendingException != null)
+          pending = true;
+      return pending;
+    } 
+  }
+
+  public static void SetPendingException(Exception e) {
+    pendingException = e;
+    lock(typeof($modulePINVOKE)) {
+      numExceptionsPending++;
+    }
+  }
+
+  public static Exception RetrievePendingException() {
+    Exception e = null;
+    if (numExceptionsPending > 0) {
+      if (pendingException != null) {
+        e = pendingException;
+        pendingException = null;
+        lock(typeof($modulePINVOKE)) {
+          numExceptionsPending--;
+        }
+      }
+    }
+    return e;
+  }
 %}
 
 %insert(runtime) %{