New update:
I found why the stackoverflow happened, and how to avoid it and make MVVM model
work. however, it did not entirely solve the problem.
The StackOverFlow was not directly because of the INotifyPropertyChanged
interface, but because I used a class derived from it.
if I define my ViewModel as
class ViewModel(System.ComponentModel.INotifyPropertyChanged):and implement all
components such as clr.clrproperty, PropertyChanged, add_PropertyChanged,
remove_PropertyChanged etc as previous posted, and assign this class to
window.DataContext, everything actually worked.
The problem is that I used a derived classclass
ViewModelBase(System.ComponentModel.INotifyPropertyChanged): where
PropertyChanged, add_PropertyChanged, remove_PropertyChanged are
implementedthenclass ViewModel(ViewModelBase): where clr.clrproperty is
implemented. This results in the StackOverflow....
To make a simpler case, I tested out the following code that is entirely
self-contained.
import clr, Systemclass
DotNetINotifyPropertyChanged(System.ComponentModel.INotifyPropertyChanged):
__namespace__ = "DotNetINotifyPropertyChanged" def __init__(self):
super(DotNetINotifyPropertyChanged, self).__init__() def
add_PropertyChanged(self, value): pass def
remove_PropertyChanged(self, value):
passc1=DotNetINotifyPropertyChanged()c1.add_PropertyChanged("text")print "C1
success"
class A(DotNetINotifyPropertyChanged): __namespace__ = "A" def
__init__(self): super(A,self).__init__()a1 =
A()a1.add_PropertyChanged("text")print "a1 success"
if you run it, you can see that "C1 success" is printed, but python can not
find a1.add_PropertyChanged method and throws exception. which I believe is the
direct cause of StackOverflow above.
Obviously, if DotNetINotifyPropertyChanged is derived from "object", the above
code runs fine.
Therefore the question is, what is it that inheriting from .NET interface that
is unique, that the method defined in base class is not inherited by child
class?
Hansong
From: [email protected]
Date: Sun, 3 Apr 2016 15:40:17 +0000
Subject: Re: [Python.NET] How to handle INotifyPropertyChanged interface
To: [email protected]; [email protected]
Yeah, it looks like the crash is probably because of the missing event
implementation as suspected. I'm a bit surprised that it didn't fail earlier
when trying to instantiate the type.
If you do get a chance to take a look at adding that functionality be sure to
submit a pull request!
Best regards,Tony
On Sun, Apr 3, 2016 at 4:30 PM Hansong Huang <[email protected]> wrote:
Tony,
thanks for the hint.
the event PropertyChanged was declared in INotifyPropertyChanged interface by
pythonnet, but obviously not implemented. [('PropertyChanged', <unbound event
'PropertyChanged'>),
anyway, the stackoverflow only happens if both following are present1. the
class is derived from INotifyPropertyChanged interface2. 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.
I was not sure if .Net event can be handled by pythonnet. I found a few
examples with IronPython, but there, a python class of "event" seems to be
implemented instead.
Below is the stack trace
[External Code] 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
mscorlib.ni.dll!00007fffb86e1ca4() Unknown
mscorlib.ni.dll!00007fffb8618272() Unknown
mscorlib.ni.dll!00007fffb867fc4a() Unknown [External Code]
mscorlib.ni.dll!00007fffb86dbaf5() Unknown
mscorlib.ni.dll!00007fffb86d281f() Unknown
System.ni.dll!00007fffb77556d4() Unknown
System.ni.dll!00007fffb7755637() Unknown
System.ni.dll!00007fffb775541d() Unknown
PresentationFramework.ni.dll!00007fff96c1ca70() Unknown
PresentationFramework.ni.dll!00007fff96c23902() Unknown
PresentationFramework.ni.dll!00007fff96c22ea1() Unknown
PresentationFramework.ni.dll!00007fff96c22693() Unknown
PresentationFramework.ni.dll!00007fff96c223c9() Unknown
PresentationFramework.ni.dll!00007fff96c21a03() Unknown
PresentationFramework.ni.dll!00007fff96c0d84c() Unknown
PresentationFramework.ni.dll!00007fff96b97299() Unknown
PresentationFramework.ni.dll!00007fff96b9720e() Unknown
PresentationFramework.ni.dll!00007fff96c852f0() Unknown
WindowsBase.ni.dll!00007fff9f6f9bc9() Unknown
WindowsBase.ni.dll!00007fff9f6f9ac6() Unknown
WindowsBase.ni.dll!00007fff9f6fca2b() Unknown
mscorlib.ni.dll!00007fffb86ca79e() Unknown
mscorlib.ni.dll!00007fffb86ca637() Unknown
mscorlib.ni.dll!00007fffb86ca5f2() Unknown
WindowsBase.ni.dll!00007fff9f913810() Unknown
WindowsBase.ni.dll!00007fff9f6fc784() Unknown
WindowsBase.ni.dll!00007fff9f6f7c24() Unknown
WindowsBase.ni.dll!00007fff9f6f8061() Unknown
WindowsBase.ni.dll!00007fff9f6f9e53() Unknown
WindowsBase.ni.dll!00007fff9f6f9d82() Unknown
WindowsBase.ni.dll!00007fff9f6f9bc9() Unknown
WindowsBase.ni.dll!00007fff9f6f9ac6() Unknown
WindowsBase.ni.dll!00007fff9f6f7583() Unknown
WindowsBase.ni.dll!00007fff9f6f94ff() Unknown
WindowsBase.ni.dll!00007fff9f8c496a() Unknown clr.dll!UMThunkStub ()
Unknown user32.dll!UserCallWinProcCheckWow() Unknown
user32.dll!DispatchMessageWorker() Unknown
WindowsBase.ni.dll!00007fff9f730ee8() Unknown
WindowsBase.ni.dll!00007fff9f70d8fc() Unknown
PresentationFramework.ni.dll!00007fff96af98b3() Unknown
PresentationFramework.ni.dll!00007fff96af969d() Unknown
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
mscorlib.ni.dll!00007fffb86e1c20() Unknown
mscorlib.ni.dll!00007fffb8618272() Unknown [External Code]
clr.dll!UMThunkStub () Unknown [External Code] >
WPFPy.py!threadStart Line 256 Python [External Code]
From: [email protected]
Date: Sun, 3 Apr 2016 15:20:47 +0000
Subject: Re: [Python.NET] How to handle INotifyPropertyChanged interface
To: [email protected]; [email protected]
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
On Sun, Apr 3, 2016 at 3:37 PM Hansong Huang <[email protected]> wrote:
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
From: [email protected]
To: [email protected]
Subject: How to handle INotifyPropertyChanged interface
Date: Thu, 31 Mar 2016 20:38:38 -0400
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 .Netclass
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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