Add typing for MachineAction

CURA-5812

cura/MachineAction.py

@@ -1,13 +1,13 @@
 # Copyright (c) 2016 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
+import os
+
 from PyQt5.QtCore import QObject, pyqtSlot, pyqtProperty, pyqtSignal
 
+from UM.Logger import Logger
 from UM.PluginObject import PluginObject
 from UM.PluginRegistry import PluginRegistry
-from UM.Application import Application
-
-import os
 
 
 ##  Machine actions are actions that are added to a specific machine type. Examples of such actions are
@@ -19,7 +19,7 @@ class MachineAction(QObject, PluginObject):
     ##  Create a new Machine action.
     #   \param key unique key of the machine action
     #   \param label Human readable label used to identify the machine action.
-    def __init__(self, key, label = ""):
+    def __init__(self, key: str, label: str = "") -> None:
         super().__init__()
         self._key = key
         self._label = label
@@ -30,14 +30,14 @@ class MachineAction(QObject, PluginObject):
     labelChanged = pyqtSignal()
     onFinished = pyqtSignal()
 
-    def getKey(self):
+    def getKey(self) -> str:
         return self._key
 
     @pyqtProperty(str, notify = labelChanged)
-    def label(self):
+    def label(self) -> str:
         return self._label
 
-    def setLabel(self, label):
+    def setLabel(self, label: str) -> None:
         if self._label != label:
             self._label = label
             self.labelChanged.emit()
@@ -46,29 +46,35 @@ class MachineAction(QObject, PluginObject):
     #   This should not be re-implemented by child classes, instead re-implement _reset.
     #   /sa _reset
     @pyqtSlot()
-    def reset(self):
+    def reset(self) -> None:
         self._finished = False
         self._reset()
 
     ##  Protected implementation of reset.
     #   /sa reset()
-    def _reset(self):
+    def _reset(self) -> None:
         pass
 
     @pyqtSlot()
-    def setFinished(self):
+    def setFinished(self) -> None:
         self._finished = True
         self._reset()
         self.onFinished.emit()
 
     @pyqtProperty(bool, notify = onFinished)
-    def finished(self):
+    def finished(self) -> bool:
         return self._finished
 
     ##  Protected helper to create a view object based on provided QML.
-    def _createViewFromQML(self):
-        path = os.path.join(PluginRegistry.getInstance().getPluginPath(self.getPluginId()), self._qml_url)
-        self._view = Application.getInstance().createQmlComponent(path, {"manager": self})
+    def _createViewFromQML(self) -> None:
+        plugin_path = PluginRegistry.getInstance().getPluginPath(self.getPluginId())
+        if plugin_path is None:
+            Logger.log("e", "Cannot create QML view: cannot find plugin path for plugin [%s]", self.getPluginId())
+            return
+        path = os.path.join(plugin_path, self._qml_url)
+
+        from cura.CuraApplication import CuraApplication
+        self._view = CuraApplication.getInstance().createQmlComponent(path, {"manager": self})
 
     @pyqtProperty(QObject, constant = True)
     def displayItem(self):