mostly worked around annoying Qt bug

portable_computing_toolkit_installer/ui/installer_wizard.py

@@ -36,7 +36,12 @@ class InstallerWizard(QtWidgets.QWizard):
         self.intro.anchorClicked.connect(self._link_clicked)
         self.license.anchorClicked.connect(self._link_clicked)
         self.selection_menu.itemClicked.connect(self._enforce_dependencies)
-        self.install_location.setValidator(Location_Validator(self))
+        self._location_validator = Location_Validator(self)
+        try:
+            self.install_location.inputRejected.connect(self.install_location.clear)
+        except AttributeError:
+            pass #inputRejected signal added in Qt 5.12, I have 5.9
+        self.install_location.setValidator(self._location_validator)
         self.location_page.registerField("Location*", self.install_location)
         self.browse_button.clicked.connect(self._select_location)
         self.selection_menu.itemClicked.connect(self._open_homepage)

portable_computing_toolkit_installer/validators/location_validator.py

@@ -3,21 +3,24 @@ import psutil
 import os
 import platform
 from pathlib import Path
-
+from threading import Lock, Condition, Event
 
 class Location_Validator(QtGui.QValidator):
+    _disposition = QtGui.QValidator.Intermediate
+    _pos = 0
+    _location = ""
+    _ntfs_location_selected = False
+    _previous_location = None
     def __init__(self, parent):
         super().__init__(parent)
         """for some reason on my Linux system, selecting a directory validates the same location repatedly,
         once for each subdir of the location.  The only way to keep it from repeatedly validating and potentially
         opening a warning window for each subdirectory in the location path was to track this and return the same
         value that was returned the last time it was validated."""
-        self._previous = {"location":"", "disposition":(QtGui.QValidator.Intermediate, "", 0,)}
-        self._ntfs_location_selected = False
 
         @property
         def ntfs_location_selected(self):
-            return self._ntfs_location_selected
+            return Location_Validator._ntfs_location_selected
 
     def _onNTFSDrive(self, location):
         """Tests if location is a path on an NTFS-formatted drive.  Returns True if path is on NTFS-formatted drive.
@@ -32,11 +35,10 @@ class Location_Validator(QtGui.QValidator):
         #elif platform.system() == "Linux":
         #    pass
         else:
-            self._ntfs_location_selected = False
-            if QtWidgets.QMessageBox.question(self.parent(), "", f"{Path(location)} is not an NTFS-formatted volume.  Tools which require a NTFS filesystem to function will not be available.  Continue anyway?") in (QtWidgets.QMessageBox.No, 0):
+            if QtWidgets.QApplication.instance().activeModalWidget():
                 return False
-            else:
-                return True
+            self._ntfs_location_selected = False
+            return not QtWidgets.QMessageBox.question(self.parent(), "", f"{Path(location)} is not an NTFS-formatted volume.  Tools which require a NTFS filesystem to function will not be available.  Continue anyway?") in (QtWidgets.QMessageBox.No, 0)
 
     def validate(self, input_, pos):
         """Called by InstallerWizard via QtWidget.QLineEdit.TextChanged signal to validate installation location input of user
@@ -46,48 +48,42 @@ class Location_Validator(QtGui.QValidator):
             pos {int} -- The current location of the cursor in the QLineEdit widget
         """
         if not input_.strip():
-            self._previous["location"] = Path(input_.strip())
-            self._previous["disposition"] = (QtGui.QValidator.Intermediate, input_, pos,)
-            return (QtGui.QValidator.Intermediate, input_, pos,)
-        elif Path(input_.strip()) == self._previous["location"]:
-            #I really hate that I have to do this
-            return self._previous["disposition"]
+            _previous_location = input_
+            return (QtGui.QValidator.Intermediate, input_, pos)
+
+        elif input_.strip() == self._previous_location:
+            return (self._disposition, self._previous_location, self._pos)
+
         elif input_.strip().endswith(r":"):
-            self._previous["location"] = Path(input_.strip())
-            self._previous["disposition"] = (QtGui.QValidator.Intermediate, input_, pos,)
-            # bugfix.  _onNTFSDrive triggers when typing the : in a drive name e.g. C:\
-            return (QtGui.QValidator.Intermediate, input_, pos,)
+            #if nothing entered or location ends with : e.g. C: which will cause _onNTFSDrive to trigger unwanted messages
+            self._location = input_
+            self._disposition = QtGui.QValidator.Intermediate
         else:
-            # because this class method is invoked via signal, it cannot handle python exceptions
-            # testing writability in Python is difficult and involves actually writing a temporary file
-            # to the directory, however, if that fails and raises an exception, it happens in Qt/C++ world
-            # and the python interpreter can't catch it, the program just crashes without any output,
-            # therefore, we will use Qt to do checking
-            input_ = os.path.expandvars(input_.strip())  # expand any environment variables in input
-            location = QtCore.QFileInfo(input_)
+            expanded_input = os.path.expandvars(input_.strip())  # expand any environment variables in input
+            location = QtCore.QFileInfo(expanded_input)
             if location.exists() and location.isDir():
-                if input_ and not self._onNTFSDrive(input_):
-                    self._previous["location"] = Path(input_)
-                    self._previous["disposition"] = (QtGui.QValidator.Intermediate, "", 0)
+                if not self._onNTFSDrive(expanded_input):
                     # clear the location, reset cursor, but allow continued edits
-                    return (QtGui.QValidator.Intermediate, "", 0)
-
-                test_file = QtCore.QTemporaryFile(f"{Path(input_)/'testXXXXXX.tmp'}")
-
-                if test_file.open(QtCore.QIODevice.ReadWrite):
-                    test_file.close()
-                    test_file.remove()
-                    self._previous["location"] = Path(input_)
-                    self._previous["disposition"] = (QtGui.QValidator.Acceptable, input_, pos,)
-                    return (QtGui.QValidator.Acceptable, input_, pos,)
+                    self._location = ""
+                    self._disposition = QtGui.QValidator.Intermediate
                 else:
-                    self._previous["location"] = Path(input_)
-                    self._previous["disposition"] = (QtGui.QValidator.Intermediate, input_, pos,)
-                    return (QtGui.QValidator.Intermediate, input_, pos,)
+                    test_file = QtCore.QTemporaryFile(f"{Path(expanded_input)/'testXXXXXX.tmp'}")
 
+                    if test_file.open(QtCore.QIODevice.ReadWrite):
+                        test_file.close()
+                        test_file.remove()
+                        self._location = input_
+                        self._disposition = QtGui.QValidator.Acceptable
+                    else:
+                        self._location = input_
+                        self._disposition = QtGui.QValidator.Intermediate
             else:
-                self._previous["location"] = Path(input_)
-                self._previous["disposition"] = (QtGui.QValidator.Intermediate, input_, pos,)
                 # I wanted to return invalid, but that would prevent input of anything not instantly acceptable
                 # or editing something acceptable to something else acceptable, passing through an invalid on the way
-                return (QtGui.QValidator.Intermediate, input_, pos,)
+                self._location = input_
+                self._disposition = QtGui.QValidator.Intermediate
+                
+            self._pos = pos
+            self._previous_location = self._location
+
+        return (self._disposition, self._location, self._pos,)