错误（CS0120）：该方法需要对象引用

Question

With the code below I get the following error, the method used is documented here . Why is the method not accepting my list of strings to create new layers?

Error (CS0120): An object reference is required for the non-static field, method, or property 'Rhino.DocObjects.Tables.LayerTable.Add(string, System.Drawing.Color)' (line 73)

Code:

  private void RunScript(List<string> x, ref object A)
  {

    for (int i = 0; i <= x.Count;i++)
    {
      Rhino.DocObjects.Tables.LayerTable.Add(x[i], Color.Black);
    }
    A = x;
  }

Line 73 is this one:

Rhino.DocObjects.Tables.LayerTable.Add(x[i], Color.Black);

Answer 1

I think you need to change it to

Rhino.DocObjects.Tables.LayerTable.Add(x[i], ref Color.Black);

Note the ref before last parameter.

EDIT

To resolve this issue you may do something like this ;

 object ob = Color.Black; //box value
 Rhino.DocObjects.Tables.LayerTable.Add(x[i], ref ob );

Answer 2

Use ref as @Tigran suggested.

Also,

• make sure x is not null
• make sure that all strings in x are valid (not null)
• Use < rather than <= in your loop. As it stands it will try to access one item beyond the end of the list and will thrown an index out of range exception.

Answer 3

The method signature in the documentation is:

public int Add(
    string layerName,
    Color layerColor
);

This is not a static method. You need to call it on an actual LayerTable object, such as in the example in the documentation:

partial class Examples
{
    public static Rhino.Commands.Result AddLayer(Rhino.RhinoDoc doc)
    {
        // <snip>
        layer_index = doc.Layers.Add(layer_name, System.Drawing.Color.Black);
        // <snip>
    }
}

In the above example, doc.Layers returns a LayerTable object that you call Add on.

Answer 4

Just add static after private.

private static void RunScript(List<string> x, ref object A)
  {

    for (int i = 0; i <= x.Count;i++)
    {
      Rhino.DocObjects.Tables.LayerTable.Add(x[i], Color.Black);
    }
    A = x;
  }