Return None if blackboard value doesn't exist.

Author: kylc

python_examples/ex02_generic_data.py

@@ -64,7 +64,9 @@ def tick(self):
 @ports(inputs=["value"])
 class Print(SyncActionNode):
     def tick(self):
-        print(self.get_input("value"))
+        value = self.get_input("value")
+        if value is not None:
+            print(value)
         return NodeStatus.SUCCESS
 
 

python_examples/ex03_stateful_nodes.py

@@ -23,9 +23,6 @@
 
      <BehaviorTree ID="MainTree">
         <Sequence>
-            <!-- Initialize the interpolated position -->
-            <SetBlackboard output_key="interpolated" value="None" />
-
             <!-- Interpolate from the initial position to the final one printing
                  at each step. -->
             <ReactiveSequence name="root">
@@ -63,7 +60,9 @@ def on_halted(self):
 @ports(inputs=["value"])
 class Print(SyncActionNode):
     def tick(self):
-        print(self.get_input("value"))
+        value = self.get_input("value")
+        if value is not None:
+            print(value)
         return NodeStatus.SUCCESS
 
 

src/python_bindings.cpp

@@ -58,7 +58,10 @@ class Py_StatefulActionNode final : public StatefulActionNode
 py::object Py_getInput(const TreeNode& node, const std::string& name)
 {
   py::object obj;
-  node.getInput(name, obj);
+  if (!node.getInput(name, obj).has_value())
+  {
+    return py::none();
+  }
   return obj;
 }