How do I create a .NET List?

[Jim_Kring]

[cross-posted to LAVA]

Does anyone know why I can't seem to find the System.Collections.Generic.List object in LabVIEW's "Select .NET Constructor" dialog?

I'm trying to create a .NET "List" in LabVIEW (Namespace: System.Collections.Generic, Assembly: mscorlib), similar to how it's done in the text-based code, below.

List<string> myList = new List<string>();

The problem is that I can't seem to find the Generic List object contstructor anywhere.

System.Collections.Generic object under the System assembly (I was only able to find System.Collections.Specialized).  I looked inside the mscorlib assembly and found the System.Collections.Generic object, but the only constructor is for something else.

 

Thanks for your help.

-Jim

Message Edited by Jim Kring on 04-11-2009 05:23 PM

[Jim_Kring · Accepted solution]

Whew...  I figured it out.  It's possible to create these generic types using reflection (dynamic object creation).

Message Edited by Jim Kring on 04-11-2009 06:17 PM

[adambe]

I am curious if this works for lists of object types as well?

I am using a customer provided API, and unfortunately most of the functions return a generic rtnObject that needs to be converted into the function specific data type. The non list returns were straightforward to convert but the list ones are providing a challenge.

Will I be better off just writting my own companion c# dll to convert these custom data types into something labview can more easily recognize?

sample C#

public override GatewayReturn GetLatestReads(
     uint gateway_id
)

Return Value
GatewayReturn with rtnObject as List of TransmitterReadMessageItem

[Wes_Ramm1]

---

@Jim Kring wrote:

Whew...  I figured it out.  It's possible to create these generic types using reflection (dynamic object creation).

Message Edited by Jim Kring on 04-11-2009 06:17 PM

---

Jim, 

I neither have the System.Type NOR the System.Activator classes / methods available with the .NET 2.0 framework.  

I can see that these are static classes (no constructor), but when I search System (2.0.0.0), I don't see classes or methods for System.Type or System.Activator.  I also don't see System.Type or System.Activator as assemblies.  MS .NET help tells me that System.Collections.Generic IS a namespace I should be able to see, but I dont.

I CAN see System.Collections.Specialized, but NOT System.Collections.Generic.

If I need to "force" labview to recognize this method using reflection, that's fine, but I can't even find the System.Type or System.Activator calls.

Specifically, what did you select when you configured these .NET invoke nodes?

Also, the string "System.Collections.Generic.List`1[System.String]" seems to have both special nomenclature and formatting.  From where did you get the information on how to format this string to invoke this method?

Just a little lost here.....

Thanks, 

Wes

[smercurio_fc]

System.Type and System.Activator are definitely part of .NET 2.0. Both these classes are sealed classes, not static classes.

In order to select a static method that a class may expose you need to:

1. Place a .NET Invoke Node on the block diagram (forget the Constructor node).
2. Right-click on the Invoke Node and go to Select Class -> .NET -> Browse.
3. In the dialog box select "mscorlib" from the "Assembly" dropdown menu.
4. Double-click on "System" to expand it. Scroll down and select "Type".
5. Click OK.
6. Now left-click on the Invoke node. A HUGE pop-up menu will display with all of the methods. You'll need to scroll down a bit (having a 60" tall monitor helps here), until you see the GetType methods. The ones you want are the ones that have "[S]" in front of them. These are the static methods. 

The same process holds for the static method for System.Activator.

[Garousi]

Hi 

I use system.Type and System.Activator for create  List of point 

but when run it . i see this error 

can you help me ?

thanks

[smercurio_fc]

The error string tells you the problem: The CreateInstance method threw an error because it was passed a null value. That means the GetType method did not work. It would not work if you passed it an invalid type. Have you verified that's a valid type?

[Garousi]

I think it is true 

[smercurio_fc]

That doesn't prove anything. The reason why you can do what you are doing on the right-hand side is that you are casting a reference to something else. Try something like this:

 

[Garousi]

thanks for your help 

I use " GMap.NET.WindowsForm.GMapPolygon ( [[GMap.NET.PointLatLng, GMap.NET.Core, Version=1.5.5.5, Culture=neutral, PublicKeyToken=b85b9027b614afef]] points , string ) "

I must put List of point , i understand that can do it by use ( system.collections.generic.list ) ,  apparently labview does not support  Generic .