[Python.NET] Passing in null as the value for a nullable type.

Wed Feb 5 21:13:30 CET 2014

That's what I thought too... but..

In [82]: System.Nullable[System.DateTime]()
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-82-97bddf8dec27> in <module>()
----> 1 System.Nullable[System.DateTime]()

TypeError: no constructor matches given arguments

In any case that would give me an actual DateTime, not a Nullable<DateTime> with HasValue = false

If only you HasValue wasn't read only ;)

Anyway, now I understand what is going on I think this is enough of an edge case not to worry about - unless someone out there has a simple fix to pythondotnet to support it.

John

From: PythonDotNet [mailto:pythondotnet-bounces+jgill=tokiomillennium.com at python.org] On Behalf Of Zane D. Purvis
Sent: Wednesday, February 05, 2014 3:36 PM
To: A list for users and developers of Python for .NET
Subject: Re: [Python.NET] Passing in null as the value for a nullable type.

Try System.Nullable[System.DateTime]()
I haven't tested that, but I think that's what you need.

On Wed, Feb 5, 2014 at 1:25 PM, John Gill <jgill at tokiomillennium.com<mailto:jgill at tokiomillennium.com>> wrote:
Thanks.   At least on my system there is no such thing as System.Null

In c# at least, null is just a keyword in the language.

From: PythonDotNet [mailto:pythondotnet-bounces+jgill<mailto:pythondotnet-bounces%2Bjgill>=tokiomillennium.com at python.org<mailto:tokiomillennium.com at python.org>] On Behalf Of Tribble, Brett
Sent: Wednesday, February 05, 2014 1:45 PM
To: A list for users and developers of Python for .NET
Subject: Re: [Python.NET] Passing in null as the value for a nullable type.

I believe you want to import System and pass System.Null. I can't remember if I've done this, but I think so.

From: PythonDotNet [mailto:pythondotnet-bounces+btribble<mailto:pythondotnet-bounces%2Bbtribble>=ea.com at python.org<mailto:ea.com at python.org>] On Behalf Of John Gill
Sent: Wednesday, February 05, 2014 8:47 AM
To: pythondotnet at python.org<mailto:pythondotnet at python.org>
Subject: [Python.NET] Passing in null as the value for a nullable type.

I am sure there is a really simple answer to this one... but so far it is eluding me.

I have a class something like this:

public class Foo
{
  ...
    public int process_date(DateTime? mydate)
   {
      ...
   }
}

I want to call this from python using pythondotnet.

Calling it like this works fine:

     mydate = DateTime(0)
     Foo().process_date(mydate)

But if I try to pass in a null as the date as follows:

    Foo().process_date(None)

I get:

   TypeError: No method matches given arguments

Hoping there is something really obvious I am missing here.

John
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