[IronPython] 'DispPropertyGet' error returned from read-write COM interop property

[Rodney Howeedy]

Stack trace for the statement that raises the SytemError:
 >>> mytestRun.Field.Item['RN_USER_01'] = 'abc'
Object reference not set to an instance of an object.
   at 
IronPython.Runtime.Types.ReflectedGetterSetter.CallTarget(CodeContext 
context, SiteLocalStorage`1 storage, MethodInfo[] targets, Object 
instance, Object[] args)
   at 
IronPython.Runtime.Types.ReflectedGetterSetter.CallSetter(CodeContext 
context, SiteLocalStorage`1 storage, Objectinstance, Object[] args, 
Object value)
   at IronPython.Runtime.Types.ReflectedIndexer.SetValue(CodeContext 
context, SiteLocalStorage`1 storage, Object[] keys, Object value)
   at 
IronPython.Runtime.Types.ReflectedIndexer.set_Item(SiteLocalStorage`1 
storage, Object[] key, Object value)
   at _stub_$1209##669(Closure , CallSite , Object , String , String )
   at 
Microsoft.Scripting.Actions.MatchCaller.Call3[T0,T1,T2,TRet](Func`5 
target, CallSite site, Object[] args)
   at Microsoft.Scripting.Actions.CallSite`1.UpdateAndExecute(Object[] args)
   at 
Microsoft.Scripting.Actions.UpdateDelegates.Update3[T,T0,T1,T2,TRet](CallSite 
site, T0 arg0, T1 arg1, T2 arg2)
   at <module>$1203##663(Closure , Scope , LanguageContext )
   at 
Microsoft.Scripting.Runtime.OptimizedScriptCode.InvokeTarget(LambdaExpression 
code, Scope scope)
   at Microsoft.Scripting.ScriptCode.Run(Scope scope)
   at 
IronPython.Hosting.PythonCommandLine.<>c__DisplayClass1.<RunOneInteraction>b__0()
SystemError: Object reference not set to an instance of an object.

Dino Viehland wrote:
> What's the stack trace for the object reference exception if you run with the -X:ExceptionDetail option?
>
> -----Original Message-----
> From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Rodney Howeedy
> Sent: Friday, December 05, 2008 3:22 PM
> To: Discussion of IronPython
> Subject: Re: [IronPython] 'DispPropertyGet' error returned from read-write COM interop property
>
> I found that one and tried before.  I didn't have any luck:
>  >>> mytestRun.Field.Item['RN_USER_01'] = 'abc'
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> SystemError: Object reference not set to an instance of an object.
>
>  >>> print mytestRun.Field.Item['RN_USER_01']
> None
>
> I couldn't decipher the error so I couldn't figure out what I'm doing
> wrong.
> I suspect the folks on this list can. =)
>
> Dino Viehland wrote:
>   
>> Does:
>>
>> mytestRun.Field.Item['RN_USER_01'] = 'abc'
>>
>> work?
>>
>> -----Original Message-----
>> From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Rodney Howeedy
>> Sent: Friday, December 05, 2008 3:11 PM
>> To: users at lists.ironpython.com
>> Subject: [IronPython] 'DispPropertyGet' error returned from read-write COM interop property
>>
>> Hi everyone,
>>
>> I encounter an error with 2.0 RC2 that didn't occur in the same
>> IronPython code on 2.0 Beta 3.
>>
>> I use a factory object from a COM interop assembly that has a read-write
>> property named "Field".  I get a TypeError when I assign a value to this
>> property (read-write):
>>  >>> mytestRun.Field['RN_USER_01'] = 'abc'
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>> TypeError: 'DispPropertyGet' object is unsubscriptable
>>
>>  >>> print mytestRun.Field['RN_USER_01']
>> None
>>
>> I imported the same COM interop assembly that worked with 2.0 Beta3.
>> The interop was converted with tlbimp.exe from a COM API .dll.  Here's
>> the 2.0 Beta3 output:
>>  >>> mytestRun.Field['RN_USER_01'] = 'abc'
>>  >>> print mytestRun.Field['RN_USER_01']
>> abc
>>
>> My best guess is that IronPython 2.0 RC2 interprets the property as
>> read-only even though the COM interop assembly defines the property
>> read-write. The error occurs in IronPython 2.0 RC2 with every COM
>> interop object with the read-write "Field" property.
>>
>> I can read the default assigned value but cannot assign anything.  Any
>> ideas?  I'm fresh out of them after trying many permutations of the syntax.
>>
>> Thank you,
>> Rodney Howeedy
>> Staff Engineer, Sun Microsystems
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>>     
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