C# create custom parameter from base class

Grasshopper Developer
,
1

Is there a simple way to create a custom parameter class inherited from GH_Param<BaseClass>, where BaseClass is an abstract class, and construct the parameter with the inherited classes?

I have the abstract class Element which have Truss, Beam and Membrane inherited from it. I woud like to generate an “abstract” parameter which would permit to transfer any generic object with a single custom parameter in Grasshopper.

1 Like
2

I don’t think so because on startup Grasshopper creates a new (fake) instance of each parameters object of your plugins to register it.

but i have no test.
if it possible, the important thing is to replace the “GH_Param.InstantiateT”

I don’t know if I’m off topic.
but do you know “BHoM” (github)

3

I’m not entirely clear on what you want, but you can create a non-abstract class derived from GH_Param<Element>, where Element is abstract. But as @kitjmv said, you’ll definitely need to override the InstantiateT method and return an actual instance of some Element derived class.

If however truss, beam, and membrane are not IGH_Goo types to begin with, you can create a single goo type which can store all Element types. That would entirely remove the abstractness from the situation.

4

Ho! so to understand it is also possible to create it with an interface ?
class MyClass: GH_Param <IMyInterface>

5

@DavidRutten @kitjmv Thanks for the help!

Actually the solution was quite simple, I have simple classes inherited from Elem, I just created an GH_Goo of Elem and created an parameter inherited from it. Just tested and I manage to recover specific methods and data from the inherited classes.

[Serializable]
public class GH_Elem : GH_Goo<Elem>
{
    public GH_Elem()
    {
        Value = new Truss();
    }
    public GH_Elem(Elem c)
    {
        Value = c;
    }

    public override bool IsValid
    {
        get
        {
            return true;
        }
    }

    public override string TypeDescription
    {
        get
        {
            return "Element";
        }
    }

    public override string TypeName
    {
        get
        {
            return "Element";
        }
    }

    public override IGH_Goo Duplicate()
    {
        GH_Elem dup = new GH_Elem();
        dup.Value = Value.DeepClone();
        return dup;
    }

    public override string ToString()
    {
        return string.Format(Value.GetType().Name.ToString() + ": " + Value.id);
    }
}

public class Param_Elem : GH_Param<GH_Elem>
{
    public Param_Elem() : base("Element", "Elem", "Element", "BATS", "0.Parameters", GH_ParamAccess.item) { }
}
1 Like
6

I already heard of BHoM, but I need my own classes as they will have specific attributes regarding structural analysis (as my project is a non-linear structural analysis plug-in). But it is in mine request list an integration with BHoM structural classes.

7

It should work. There are two parameters based on IGH_Goo and IGH_GeometricGoo in the standard set, and those are both interfaces.

1 Like
8

I think I’m running into a related issue. I have a number of custom GH_Goo types, some of which contain interfaces (GH_Goo<Interface>) and some that contain abstract classes (GH_Goo<AbstractClass>). Creating a custom GH_Param of either seems to work, in that my custom components that use my custom Params function as expected.

However, the Params that contain an abstract class (GH_Param<GH_Goo<AbstractClass>>) do not show up in the component library or in search. In other words, you can’t place a floating abstract class param on the canvas.

On the other hand, GH_Param<GH_Goo<Interface>> appears in search/library as expected.

Any ideas on why this is happening?