How to inherit point3d?

I hope to creat a class that inherit from point3d

"myPoint3d" add one attribute to show the distance with other points in the one input List.

i have tried:

class myPoint3d : Rhino.Geometry.Point3d {
}

but it doesnot work......

How to inherit point3d?via c# or vb,perfer c#

Thank you very much!!

Replies to This Discussion

Permalink Reply by Giulio Piacentino on November 30, 2011 at 12:03pm

Hi Andrea

you cannot derive from a struct in C# and Vb.Net, not you can do so in Python.
In .Net, you can only derive from non-sealed classes and implement (derive) interfaces.

In Python, if you try deriving from Point3d, you will receive this message:
"Cannot derive from Rhino.Geometry.Point3d because it is a value type".

http://msdn.microsoft.com/en-us/library/ms173149.aspx

What are you trying to do?

- Giulio
______________
giulio@mcneel.com

Permalink Reply by Andrea Lu on November 30, 2011 at 12:10pm

Hi,Giulio

I just want to create a class mypoint3d which inherit the properties(such as x,y,z position) from the Point3d.....can u tell me how to scri

Gracias!

Permalink Reply by Giulio Piacentino on November 30, 2011 at 12:46pm

Hi Andrea

Point3d represents a value: therefore inheritance cannot be achieved. That's just it.

What you can do, though, is store a Point3d inside your class and the use its properties and methods from within it. *

For example, if you are making a simplified model of the Solar System, you might create a Planet class, with Position, Radius and Color properties. Then Earth and Mars are two instances of the Planet class, each with a different Position and Radius. Also, Earth will be assigned color blue, Mars color red.

Please have a look at any Python, Vb.Net or C# references, especially books, about how and why things are specified this way. A full explanation here would be very very long!

I am copying some links from here:

Rhino 4 VB.NET SDk Pages - Contains reference material for the VB.NEt SDK and sample code.
VB.NET School - Covers all you need to know to start programming in VB.NET.
C# School - Covers all you need to know to start programming in C#.
Other Developer learning resources - Various links for general programming information.

Do you need any other book link or general pointer?

Cheers,

- Giulio
______________
giulio@mcneel.com

* other two alternatives could be: create your own MyPoint3d class/struct that does not have things in common with Point3d and either store a single Point3d field within it, or re-implement the properties. But why?

Permalink Reply by Andrea Lu on November 30, 2011 at 1:10pm

thank you for helping me,Giulio

i will try to learn!!!!!

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