Thanks Brad.

 

I think I understand what is happening now.   Note that the C# code I posted works fine, you can pass in Null as mydate.

 

DateTime? mydate

 

Gets translated by the C# compiler to System.Nullable<DateTime> mydate.

 

When you pass in null to the method C# sets up a Nullable<DateTime> with the HasValue set to False.

 

As far as I can tell there is no way to create such a thing in pythondotnet.   Not sure whether this is a bug or a feature, but certainly explains why it is dazed and confused when I try to pass in None, it isn’t prepared to match the DateTime?.

 

In this case, I have control of the C# code so I can just overload the method and work around this.

 

Thanks for helping me understand what is going on.

 

John

 

From: PythonDotNet [mailto:pythondotnet-bounces+jgill=tokiomillennium.com@python.org] On Behalf Of Brad Friedman
Sent: Wednesday, February 05, 2014 2:43 PM
To: A list for users and developers of Python for .NET
Cc: pythondotnet@python.org
Subject: Re: [Python.NET] Passing in null as the value for a nullable type.

 

DateTime is a struct. You have to pass a value. It should not take null.  If you tried to do that in c# it would not allow it either. 


On Feb 5, 2014, at 11:46 AM, John Gill <jgill@tokiomillennium.com> wrote:

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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