Fixes in GraphDataHandling

    - return field in add_array
    - add `simulate_only` parameter to call_kernel

src/pystencils_autodiff/graph_datahandling.py

@@ -168,20 +168,21 @@ class GraphDataHandling(pystencils.datahandling.SerialDataHandling):
                   alignment=False,
                   field_type=FieldType.GENERIC):
 
-        super().add_array(name,
-                          values_per_cell,
-                          dtype,
-                          latex_name,
-                          ghost_layers,
-                          layout,
-                          cpu,
-                          gpu,
-                          alignment,
-                          field_type)
+        rtn = super().add_array(name,
+                                values_per_cell,
+                                dtype,
+                                latex_name,
+                                ghost_layers,
+                                layout,
+                                cpu,
+                                gpu,
+                                alignment,
+                                field_type)
         if cpu:
             self.call_queue.append(DataTransfer(self._fields[name], DataTransferKind.HOST_ALLOC))
         if gpu:
             self.call_queue.append(DataTransfer(self._fields[name], DataTransferKind.DEVICE_ALLOC))
+        return rtn
 
     def add_custom_data(self, name, cpu_creation_function,
                         gpu_creation_function=None, cpu_to_gpu_transfer_func=None, gpu_to_cpu_transfer_func=None):
@@ -200,10 +201,10 @@ class GraphDataHandling(pystencils.datahandling.SerialDataHandling):
         self.call_queue.append(Swap(self._fields[name1], self._fields[name2], gpu))
         super().swap(name1, name2, gpu)
 
-    def run_kernel(self, kernel_function, **kwargs):
+    def run_kernel(self, kernel_function, simulate_only=False, **kwargs):
         self.call_queue.append(KernelCall(kernel_function, kwargs))
-        super().run_kernel(kernel_function, **kwargs)
-        # skip calling super
+        if not simulate_only:
+            super().run_kernel(kernel_function, **kwargs)
 
     def to_cpu(self, name):
         super().to_cpu(name)