[Python.NET] Problem with System.ArgumentException in call to method from dll

[Barton]

Two things spring instantly to mind (thanks for the reminder)
1) A patch has been submitted that tries very cleverly to allow out 
params to be omitted. This sounds like it's worth pursuing.
2) iPy's Reference type is something that I looked into implementing 
which would (or could) allow the wrapper to function more like (or just 
the same as) the C# being wrapped, writing the value directly on the 
given out param.

Oh, boy; I'm starting to get excited by the possibilities.
Thanks all,
Barton

On 01/23/2013 06:23 AM, brad at fie.us wrote:
> Out of curiosity Barton, could you pass "None" rather than constructing instances?  Or does it truly need the argument to have a type in order to disambiguate overloaded methods?
>
> Also, it is my understanding that in iPy, out parameters are often omitted from the method's arguments.  But in Python.Net they remain in the header.  I assume this is because removing the out parameters potentially creates a lot of ambiguity between overloads?
>
> I'm wondering if it might be appropriate for PythonNet to define a type to make it possible to remove ambiguity.
>
> i.e.:
> c#:
> public bool DoJob(int data1, int data2, out string result) { …}
>
> python:
> doer = Doer()
> doResult = doer.DoJob(1,2,clr.OutParam(string))
> if (doResult[0]):
>     print(doResult[1])
> else:
>     print("error")
>
> The key being: python net will never ever never let an OutParam object through to the clr.  Therefore, the following should throw an exception.
>
> clr.OutParam(clr.OutParam)
>
> Therefore, you would never run into reflective ambiguity.
>
> On Jan 23, 2013, at 5:52 AM, Barton <barton at bcdesignswell.com> wrote:
>
>> The Python.Runtime is a bit tricky when it comes to out parameters:
>> In C# DateTime.TryParse(String, out DateTime) becomes
>>
>>>>> d = DateTime(0)    # just a dummy to call the method on
>>>>> d2 = DateTime(0) # another dummy to satisfy the out parameter (could be the same instance, d)
>> # d3 is were the result is passed out
>>>>> result, d3 = d.TryParse("2013/01/22", d2)
>>>>> d3.ToString()
>> u'1/22/2013 12:00:00 AM'
>>>>> # this is the same behavior as iPy
>>
>>
>> I can't test this - I'm on Linux, but:
>> Here you've given the type (class)
>> from System.Windows.Media.Imaging import BitmapSource
>> bitmapsrc = BitmapSource
>> print bitmapsrc
>> cam = xiCam()
>> cam.OpenDevice(0)
>> cam.SetParam(PRM.BUFFER_POLICY, BUFF_POLICY.SAFE)
>> cam.SetParam(PRM.IMAGE_DATA_FORMAT,  IMG_FORMAT.MONO8)
>> cam.StartAcquisition()
>> timeout = 1000
>> bitmapsrc = cam.GetImage(bitmapsrc, timeout)
>> cam.StopAcquisition()
>> ##
>>
>> Console output:
>> <class 'System.Windows.Media.Imaging.BitmapSource'>
>>
>> What you need is an instance, perhaps:
>> bitmapsrc = BitmapSource() # or something to that effect.
>>
>> On 01/22/2013 11:58 AM, Daniel Krause wrote:
>>> from System.Windows.Media.Imaging import BitmapSource
>>> bitmapsrc = BitmapSource
>>> print bitmapsrc
>>> cam = xiCam()
>>> cam.OpenDevice(0)
>>> cam.SetParam(PRM.BUFFER_POLICY, BUFF_POLICY.SAFE)
>>> cam.SetParam(PRM.IMAGE_DATA_FORMAT,  IMG_FORMAT.MONO8)
>>> cam.StartAcquisition()
>>> timeout = 1000
>>> bitmapsrc = cam.GetImage(bitmapsrc, timeout)
>>> cam.StopAcquisition()
>>> ##
>>>
>>> Console output:
>>> <class 'System.Windows.Media.Imaging.BitmapSource'>
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