Resolve circular imports for CuraAPI

cura/API/Account.py

@@ -1,15 +1,18 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
-from typing import Optional, Dict
+from typing import Optional, Dict, TYPE_CHECKING
 
 from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot, pyqtProperty
 
+from UM.i18n import i18nCatalog
 from UM.Message import Message
+
 from cura.OAuth2.AuthorizationService import AuthorizationService
 from cura.OAuth2.Models import OAuth2Settings
-from UM.Application import Application
 
-from UM.i18n import i18nCatalog
+if TYPE_CHECKING:
+    from cura.CuraApplication import CuraApplication
+
 i18n_catalog = i18nCatalog("cura")
 
 
@@ -26,8 +29,9 @@ class Account(QObject):
     # Signal emitted when user logged in or out.
     loginStateChanged = pyqtSignal(bool)
 
-    def __init__(self, parent = None) -> None:
+    def __init__(self, application: "CuraApplication", parent = None) -> None:
         super().__init__(parent)
+        self._application = application
 
         self._error_message = None  # type: Optional[Message]
         self._logged_in = False
@@ -47,7 +51,11 @@ class Account(QObject):
             AUTH_FAILED_REDIRECT="{}/app/auth-error".format(self._oauth_root)
         )
 
-        self._authorization_service = AuthorizationService(Application.getInstance().getPreferences(), self._oauth_settings)
+        self._authorization_service = AuthorizationService(self._oauth_settings)
+
+    def initialize(self) -> None:
+        self._authorization_service.initialize(self._application.getPreferences())
+
         self._authorization_service.onAuthStateChanged.connect(self._onLoginStateChanged)
         self._authorization_service.onAuthenticationError.connect(self._onLoginStateChanged)
         self._authorization_service.loadAuthDataFromPreferences()

cura/API/Backups.py

@@ -1,9 +1,12 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
-from typing import Tuple, Optional
+from typing import Tuple, Optional, TYPE_CHECKING
 
 from cura.Backups.BackupsManager import BackupsManager
 
+if TYPE_CHECKING:
+    from cura.CuraApplication import CuraApplication
+
 
 ##  The back-ups API provides a version-proof bridge between Cura's
 #   BackupManager and plug-ins that hook into it.
@@ -13,9 +16,10 @@ from cura.Backups.BackupsManager import BackupsManager
 #       api = CuraAPI()
 #       api.backups.createBackup()
 #       api.backups.restoreBackup(my_zip_file, {"cura_release": "3.1"})``
-
 class Backups:
-    manager = BackupsManager()  # Re-used instance of the backups manager.
+
+    def __init__(self, application: "CuraApplication") -> None:
+        self.manager = BackupsManager(application)
 
     ##  Create a new back-up using the BackupsManager.
     #   \return Tuple containing a ZIP file with the back-up data and a dict

cura/API/Interface/Settings.py

@@ -1,8 +1,12 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
     from cura.CuraApplication import CuraApplication
 
+
 ##  The Interface.Settings API provides a version-proof bridge between Cura's
 #   (currently) sidebar UI and plug-ins that hook into it.
 #
@@ -19,8 +23,9 @@ from cura.CuraApplication import CuraApplication
 #       api.interface.settings.addContextMenuItem(data)``
 
 class Settings:
-    # Re-used instance of Cura:
-    application = CuraApplication.getInstance()  # type: CuraApplication
+
+    def __init__(self, application: "CuraApplication") -> None:
+        self.application = application
 
     ##  Add items to the sidebar context menu.
     #   \param menu_item dict containing the menu item to add.

cura/API/Interface/__init__.py

@@ -1,9 +1,15 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
+from typing import TYPE_CHECKING
+
 from UM.PluginRegistry import PluginRegistry
 from cura.API.Interface.Settings import Settings
 
+if TYPE_CHECKING:
+    from cura.CuraApplication import CuraApplication
+
+
 ##  The Interface class serves as a common root for the specific API
 #   methods for each interface element.
 #
@@ -20,5 +26,6 @@ class Interface:
     # For now we use the same API version to be consistent.
     VERSION = PluginRegistry.APIVersion
 
+    def __init__(self, application: "CuraApplication") -> None:
         # API methods specific to the settings portion of the UI
-    settings = Settings()
+        self.settings = Settings(application)

cura/API/__init__.py

@@ -1,5 +1,7 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
+from typing import Optional, TYPE_CHECKING
+
 from PyQt5.QtCore import QObject, pyqtProperty
 
 from UM.PluginRegistry import PluginRegistry
@@ -7,6 +9,9 @@ from cura.API.Backups import Backups
 from cura.API.Interface import Interface
 from cura.API.Account import Account
 
+if TYPE_CHECKING:
+    from cura.CuraApplication import CuraApplication
+
 
 ##  The official Cura API that plug-ins can use to interact with Cura.
 #
@@ -19,14 +24,30 @@ class CuraAPI(QObject):
     # For now we use the same API version to be consistent.
     VERSION = PluginRegistry.APIVersion
 
+    def __init__(self, application: "CuraApplication") -> None:
+        super().__init__(parent = application)
+        self._application = application
+
+        # Accounts API
+        self._account = Account(self._application)
+
         # Backups API
-    backups = Backups()
+        self._backups = Backups(self._application)
 
         # Interface API
-    interface = Interface()
+        self._interface = Interface(self._application)
 
-    _account = Account()
+    def initialize(self) -> None:
+        self._account.initialize()
 
     @pyqtProperty(QObject, constant = True)
-    def account(self) -> Account:
-        return CuraAPI._account
+    def account(self) -> "Account":
+        return self._account
+
+    @property
+    def backups(self) -> "Backups":
+        return self._backups
+
+    @property
+    def interface(self) -> "Interface":
+        return self._interface

cura/Backups/BackupsManager.py

@@ -1,10 +1,12 @@
 # Copyright (c) 2018 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
-from typing import Dict, Optional, Tuple
+from typing import Dict, Optional, Tuple, TYPE_CHECKING
 
 from UM.Logger import Logger
 from cura.Backups.Backup import Backup
+
+if TYPE_CHECKING:
     from cura.CuraApplication import CuraApplication
 
 
@@ -13,8 +15,8 @@ from cura.CuraApplication import CuraApplication
 #
 #   Back-ups themselves are represented in a different class.
 class BackupsManager:
-    def __init__(self):
-        self._application = CuraApplication.getInstance()
+    def __init__(self, application: "CuraApplication") -> None:
+        self._application = application
 
     ##  Get a back-up of the current configuration.
     #   \return A tuple containing a ZipFile (the actual back-up) and a dict

cura/CuraApplication.py

@@ -44,6 +44,7 @@ from UM.Operations.RemoveSceneNodeOperation import RemoveSceneNodeOperation
 from UM.Operations.GroupedOperation import GroupedOperation
 from UM.Operations.SetTransformOperation import SetTransformOperation
 
+from cura.API import CuraAPI
 from cura.Arranging.Arrange import Arrange
 from cura.Arranging.ArrangeObjectsJob import ArrangeObjectsJob
 from cura.Arranging.ArrangeObjectsAllBuildPlatesJob import ArrangeObjectsAllBuildPlatesJob
@@ -204,7 +205,7 @@ class CuraApplication(QtApplication):
 
         self._quality_profile_drop_down_menu_model = None
         self._custom_quality_profile_drop_down_menu_model = None
-        self._cura_API = None
+        self._cura_API = CuraAPI(self)
 
         self._physics = None
         self._volume = None
@@ -713,6 +714,9 @@ class CuraApplication(QtApplication):
         default_visibility_profile = self._setting_visibility_presets_model.getItem(0)
         self.getPreferences().setDefault("general/visible_settings", ";".join(default_visibility_profile["settings"]))
 
+        # Initialize Cura API
+        self._cura_API.initialize()
+
         # Detect in which mode to run and execute that mode
         if self._is_headless:
             self.runWithoutGUI()
@@ -900,10 +904,7 @@ class CuraApplication(QtApplication):
             self._custom_quality_profile_drop_down_menu_model = CustomQualityProfilesDropDownMenuModel(self)
         return self._custom_quality_profile_drop_down_menu_model
 
-    def getCuraAPI(self, *args, **kwargs):
-        if self._cura_API is None:
-            from cura.API import CuraAPI
-            self._cura_API = CuraAPI()
+    def getCuraAPI(self, *args, **kwargs) -> "CuraAPI":
         return self._cura_API
 
     ##  Registers objects for the QML engine to use.

cura/OAuth2/AuthorizationService.py

@@ -29,7 +29,7 @@ class AuthorizationService:
     # Emit signal when authentication failed.
     onAuthenticationError = Signal()
 
-    def __init__(self, preferences: Optional["Preferences"], settings: "OAuth2Settings") -> None:
+    def __init__(self, settings: "OAuth2Settings", preferences: Optional["Preferences"] = None) -> None:
         self._settings = settings
         self._auth_helpers = AuthorizationHelpers(settings)
         self._auth_url = "{}/authorize".format(self._settings.OAUTH_SERVER_URL)
@@ -38,6 +38,8 @@ class AuthorizationService:
         self._preferences = preferences
         self._server = LocalAuthorizationServer(self._auth_helpers, self._onAuthStateChanged, daemon=True)
 
+    def initialize(self, preferences: Optional["Preferences"] = None) -> None:
+        self._preferences = preferences
         if self._preferences:
             self._preferences.addPreference(self._settings.AUTH_DATA_PREFERENCE_KEY, "{}")