C# Grasshopper Component inheritance

Petras_Vestartas · April 9, 2018, 1:58pm

Hi,

I have basic question about class inheritance.

I have created Grasshopper component base class, not to write the same things for each component:

When I inherit this class in another component, like this below and I have two the same components on grasshopper canvas. One of them will overwrite/change variables such as preview, bbox, m, lines, directory or other variables from base class. Will it only be affected/changed for one component only while other will have initial values?

nathanletwory · April 9, 2018, 2:03pm

That should work fine. This is what I use for GhShaderNodes as well, where I actually have a chain of base classes:

github.com

mcneel/GhShaderNodes/blob/master/ShaderGraphComponents/MathNodes.cs

using ccl.ShaderNodes;
using GH_IO.Serialization;
using Grasshopper.Kernel;
using ShaderGraphResources;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ShaderGraphComponents
{

	public class MathBaseNode : CyclesNode {
		public MathBaseNode(Type mathop, MathNode.Operations openum, string category, string subcategory, string outputdescription, Func<float, float, float> op) : base(
			openum.ToString().Replace('_', ' '),
			openum.ToString().Replace('_', ' '),
			openum.ToString().Replace('_', ' '),

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I have a CyclesNode class deriving from GH_Component. This is where I essentially dynamically create the inputs and outputs based on the types in ccl.ShaderNodes.* and some extra stuff for the heavy lifting. Then for the math nodes I have yet another base class MathBaseNode deriving from CyclesNode.

This all works fine.

Petras_Vestartas · April 9, 2018, 2:08pm

Thank you just wanted to be sure before inheriting in all components:)

Dani_Abalde · April 9, 2018, 3:12pm

To make a GH_Component base class, declare it as abstract to force inheritors to overwrite methods that it does not overwrite, such as Guid, It’s just good practice I think.

Regarding your question, it depends on the implementation. If the fields are not declared static, in principle they should not share the values.

dale · April 9, 2018, 9:08pm

Hi @Petras_Vestartas,

Here is a sample that demonstrates GH_Component inheritance if you need one.

https://github.com/mcneel/rhino-developer-samples/tree/5/grasshopper/cs/SamplePlatonics

– Dale