Question

I have this namespace in Extensions.cs file:

namespace TextBoxExtensions
{
    public static class TextBoxExtensionsClass
    {
        public static void ResetColor(this Label label)
        {
            label.ForeColor = new TextBox().ForeColor;
        }
    }
}

then:

using TextBoxExtensions;

//…

textbox.ResetColor();

when I try to access it in another file, I get the following error:

‘System.Windows.Forms.TextBox’ does not contain a definition for ‘ResetColor’ and the best extension method overload ‘TextBoxExtensions.TextBoxExtensionsClass.ResetColor(System.Windows.Forms.Label)’ has some invalid arguments

Answer 1

what type is textbox? your extention is for a Label object. I am guessing that this is your problem…. that your textbox object is not of type Label