the event PropertyChanged was declared in INotifyPropertyChanged interface by pythonnet, but obviously not implemented.
1. the class is derived from INotifyPropertyChanged interface
2. the class exposes property back to .Net vis @clrproperty
which seems to prove that it is the PropertyChanged event that is not implemented in python class resulted in the crash.
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clr.dll!CallDescrWorkerInternal () Unknown
clr.dll!CallDescrWorkerWithHandler(struct CallDescrData *,int) Unknown
clr.dll!CallDescrWorkerReflectionWrapper(struct CallDescrData *,class Frame *) Unknown
clr.dll!RuntimeMethodHandle::InvokeMethod(class Object *,class PtrArray *,class SignatureNative *,bool) Unknown
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clr.dll!UMThunkStub () Unknown
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> WPFPy.py!threadStart Line 256 Python
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From: tony@pyxll.com
Date: Sun, 3 Apr 2016 15:20:47 +0000
Subject: Re: [Python.NET] How to handle INotifyPropertyChanged interface
To: hhspiny@pine.cc; pythondotnet@python.org
What's the full stack trace?
I suspect it's something to do with the event declared on the interface not being implemented. The managed type constructed doesn't define any events, so that would cause the construction of the type of fail - which is probably the error you're getting (although without the stack trace it's just an educated guess).
It shouldn't be too hard to add events to the derived type if someone wanted to have a go at implementing it. The code is in the CreateDerivedType method in src/runtime/classderived.cs. To be consistent with how methods and properties work, it would need a clrevent function adding to the clr module (src/runtime/resource/clr.py) - maybe it could work like this:
class MyClass(INotifyPropertyChanged):
OnPropertyChanged = clr.clrevent(event_attributes, event_type)
Then in classderived.cs the class any clrevents on the python class could be added to the managed type using TypeBuilder.DefineEvent.
So, anyway - short answer is that what you're trying to do won't work without changes to pythonnet; but the changes required shouldn't be too hard if you wanted to have a go.
Best regards,
Tony
It seems inheriting from INotifyPropertyChanged is the cause
self.window = System.Windows.Markup.XamlReader.Load(outStream)
self.window.DataContext = MyViewModel()
class MyViewModel(System.Object):
__namespace__ = "WPFPyDemo"
def __init__(self):
super(MyViewModel,self).__init__()
self._inputText = "Line - in"
@clr.clrproperty(str)
def inputText(self):
return self._inputText
@inputText.setter
def inputText(self,value):
self._inputText = value
self.OnPropertyChanged("inputText")
The above code works fine.
but if switch inheritance to
class MyViewModel(System.ComponentModel.INotifyPropertyChanged):
and nothing else changed, python gives
"The process terminates due to StackOverflowException"
Not sure why.
Thanks for the help
I am still trying to figure out how to implement WPF MVVM with Python.Net.
Previously, I have successfully used System.Dynamic.ExpandoObject as a ViewModel container
self.window = System.Windows.Markup.XamlReader.Load(outStream)
self.window.DataContext = DotNetExpandoObject()
where DotNetExpandoObject is a wrapper class for System.Dynamic.ExpandoObject
class DotNetExpandoObject(System.Dynamic.ExpandoObject):
... in which I redefined __getattr__ and __setattr__
it works flawlessly as System.Dynamic.ExpandoObject implements INotifyPropertyChange interface already
Now, I would like to get away from using System.Dynamic.ExpandoObject but to implement my own
I first tried to expose a python class back to .Net
class MyViewModel(System.Object):
__namespace__ = "WPFPyDemo"
def __init__(self):
super(MyViewModel,self).__init__()
self._inputText = "Line - in"
@clr.clrproperty(str)
def inputText(self):
return self._inputText
@inputText.setter
def inputText(self,value):
self._inputText = value
self.OnPropertyChanged("inputText")
self.window.DataContext = MyViewModel()
The one direction data binding works fine, and the "Line - in" text correctly shows up in the textblock control.
obviously this is not sufficient as there is no INotifyPropertyChange interface.
So, I inherit the interface , and tries to implement the typical C# code
" public event PropertyChangedEventHandler PropertyChanged"
-- not sure how to handle event in Python.Net, the follow code probably is completely wrong
class ViewModel(System.ComponentModel.INotifyPropertyChanged):
__namespace__ = "WPFPy"
def __init__(self):
super(ViewModel, self).__init__()
self.PropertyChanged = System.ComponentModel.PropertyChangedEventHandler
def OnPropertyChanged(self, propertyName):
if self.PropertyChanged != None:
PropertyChanged(self, System.ComponentModel.PropertyChangedEventArgs(propertyName))
class MyViewModel(ViewModel):
__namespace__ = "WPFPyDemo"
def __init__(self):
super(MyViewModel,self).__init__()
self._inputText = "Line - in"
@clr.clrproperty(str)
def inputText(self):
return self._inputText
@inputText.setter
def inputText(self,value):
self._inputText = value
self.OnPropertyChanged("inputText")
The process terminates due to StackOverflowException.
Looks like the error happens when WFP recoganized INotifyPropertyChange interface and tries to access MyViewModel class via it.
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