Use application singleton instead of locally cached application

cura/NetworkClient.py

@@ -7,8 +7,8 @@ from PyQt5.QtCore import QUrl
 from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkReply, QHttpMultiPart, QNetworkRequest, QHttpPart, \
     QAuthenticator
 
+from UM.Application import Application
 from UM.Logger import Logger
-from cura.CuraApplication import CuraApplication
 
 
 ##  Abstraction of QNetworkAccessManager for easier networking in Cura.
@@ -17,9 +17,6 @@ class NetworkClient:
     
     def __init__(self) -> None:
         
-        # Use the given application instance or get the singleton instance.
-        self._application = CuraApplication.getInstance()
-        
         # Network manager instance to use for this client.
         self._manager = None  # type: Optional[QNetworkAccessManager]
         
@@ -29,7 +26,8 @@ class NetworkClient:
         self._last_request_time = None  # type: Optional[float]
         
         # The user agent of Cura.
-        self._user_agent = "%s/%s " % (self._application.getApplicationName(), self._application.getVersion())
+        application = Application.getInstance()
+        self._user_agent = "%s/%s " % (application.getApplicationName(), application.getVersion())
 
         # Uses to store callback methods for finished network requests.
         # This allows us to register network calls with a callback directly instead of having to dissect the reply.

plugins/UM3NetworkPrinting/src/Cloud/CloudOutputDeviceManager.py

@@ -6,6 +6,7 @@ from typing import Dict, Optional
 from PyQt5.QtNetwork import QNetworkRequest, QNetworkReply
 
 from UM.Logger import Logger
+from cura.CuraApplication import CuraApplication
 from cura.NetworkClient import NetworkClient
 from plugins.UM3NetworkPrinting.src.Cloud.CloudOutputDevice import CloudOutputDevice
 from .Models import Cluster
@@ -26,14 +27,15 @@ class CloudOutputDeviceManager(NetworkClient):
     def __init__(self):
         super().__init__()
 
-        self._output_device_manager = self._application.getOutputDeviceManager()
-        self._account = self._application.getCuraAPI().account
-        
         # Persistent dict containing the remote clusters for the authenticated user.
         self._remote_clusters = {}  # type: Dict[str, CloudOutputDevice]
 
+        application = CuraApplication.getInstance()
+        self._output_device_manager = application.getOutputDeviceManager()
+        self._account = application.getCuraAPI().account
+        
         # When switching machines we check if we have to activate a remote cluster.
-        self._application.globalContainerStackChanged.connect(self._activeMachineChanged)
+        application.globalContainerStackChanged.connect(self._activeMachineChanged)
 
         # Fetch all remote clusters for the authenticated user.
         # TODO: update remote clusters periodically
@@ -96,7 +98,7 @@ class CloudOutputDeviceManager(NetworkClient):
     
     ##  Callback for when the active machine was changed by the user.
     def _activeMachineChanged(self):
-        active_machine = self._application.getGlobalContainerStack()
+        active_machine = CuraApplication.getInstance().getGlobalContainerStack()
         if not active_machine:
             return