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Hi all, I've found a bug in IronPython 2.6.1 that causes to terminate IronPython 2.6.1 based on .NET 2.0 with SystemError: Object reference not set to an instance of an object. exception. Below is the code. You need clrtype.py and pyevent.py to run it. When you run it, a simple form with listbox and checkbox appears. The SK items in the listbox can be filtered out by checking the checkbox. There is a binding to the selected item in the listbox which is the cause of the error. If you select the SK item and check the checkbox to filter it out, the exception occurs. But it only occurs in IronPython based on .NET 2.0 - it works fine in IronPython 2.6.1 based on .NET 4. Here is the full exception: C:\BindingTest>C:\IronPython-2.6.1.NET20\ipy.exe -X:Debug -X:ShowClrExceptions BindingTest.py Traceback (most recent call last): File "BindingTest.py", line 133, in <module> File "BindingTest.py", line 125, in filtered SystemError: Object reference not set to an instance of an object. CLR Exception: NullReferenceException : Object reference not set to an instance of an object. I'm going to build IronPython in the debug mode this afternoon to see what's wrong inside and possible fix it in my own build. As this is quite showstopper for me, I would be very happy if somebody can help me with this. Thank you. -- -- Lukáš --- file BindingTest.py --- import clr import clrtype import pyevent clr.AddReference('WindowsBase') clr.AddReference('PresentationFramework') from System.Windows import Application from System.ComponentModel import INotifyPropertyChanged, PropertyChangedEventArgs from System.Collections.ObjectModel import ObservableCollection from System.Windows.Markup import XamlReader from System.Windows.Data import CollectionViewSource xaml = """<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Binding test" Height="150" Width="250"> <Grid x:Name="root"> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="*" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <CheckBox Content="Filtered" IsChecked="{Binding filtered}" /> <ListBox Name="lbxMountains" Grid.Row="1" ItemsSource="{Binding lstMountains}" SelectedItem="{Binding selMountain}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBlock Grid.Column="1" Text="{Binding country}" /> <TextBlock Text=": " /> <TextBlock Text="{Binding name}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> <TextBlock Grid.Row="2" Text="{Binding selMountain.name}" /> </Grid> </Window>""" class NotifyPropertyChangedBase(INotifyPropertyChanged): PropertyChanged = None def __init__(self): self.PropertyChanged, self._propertyChangedCaller = pyevent.make_event() def add_PropertyChanged(self, value): self.PropertyChanged += value def remove_PropertyChanged(self, value): self.PropertyChanged -= value def OnPropertyChanged(self, propertyName): if self.PropertyChanged is not None: self._propertyChangedCaller(self, PropertyChangedEventArgs(propertyName)) class Mountain(NotifyPropertyChangedBase): __metaclass__ = clrtype.ClrClass def __init__(self, name, country): super(Mountain, self).__init__() self.name = name self.country = country @property def name(self): return self._name @name.setter def name(self, value): self._name = value self.OnPropertyChanged('name') @property def country(self): return self._country @country.setter def country(self, value): self._country = value self.OnPropertyChanged('country') class Mountains(NotifyPropertyChangedBase): __metaclass__ = clrtype.ClrClass def __init__(self): super(Mountains, self).__init__() self._lstMountains = ObservableCollection[Mountain]() self.lstMountains.Add(Mountain('Snezka', 'CR')) self.lstMountains.Add(Mountain('Rip', 'CR')) self.lstMountains.Add(Mountain('Gerlach', 'SK')) self.filtered = False self.selMountain = Mountain('', '') @property @clrtype.accepts() @clrtype.returns(Mountain) def selMountain(self): return self._selMountain @selMountain.setter @clrtype.accepts(Mountain) @clrtype.returns() def selMountain(self, value): self._selMountain = value self.OnPropertyChanged('selMountain') @property @clrtype.accepts() @clrtype.returns(ObservableCollection[Mountain]) def lstMountains(self): return self._lstMountains @property @clrtype.accepts() @clrtype.returns(bool) def filtered(self): return self._filtered @filtered.setter @clrtype.accepts(bool) @clrtype.returns() def filtered(self, value): self._filtered = value self.OnPropertyChanged('filtered') dv = CollectionViewSource.GetDefaultView(self.lstMountains) dv.Filter = (lambda x: x.country == 'CR' if value else True) class MyApp: def __init__(self): self.root = XamlReader.Parse(xaml) self.root.DataContext = Mountains() app = Application() app.Run(MyApp().root) |
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