C# 4.0: Can I use a Color as an optional parameter with a default value?

c# optional-parameters
DTown picture DTown · May 10, 2010 · Viewed 31.9k times · Source 
    public void log(String msg, Color c = Color.black)
    {
        loggerText.ForeColor = c;
        loggerText.AppendText("\n" + msg);

    }

This results in an error that c must be a compile-time constant. I've read up on this a little and most examples are dealing with strings and ints. I've figured out I can use the colorconverter class but I'm not sure it will be very efficient. Is there a way to just pass a basic color as an optional parameter?

    public void log(String msg, String c = "Black")
    {
        ColorConverter conv = new ColorConverter();
        Color color = (Color)conv.ConvertFromString(c);

        loggerText.ForeColor = color;
        loggerText.AppendText("\n" + msg);
    }

Answer

scobi picture scobi · May 10, 2010

I've run into this as well and the only workaround I've found is to use nullables.

public void log(String msg, Color? c = null)
{
    loggerText.ForeColor = c ?? Color.Black;
    loggerText.AppendText("\n" + msg);
}

Other possible syntax is:

loggerText.ForeColor = c.GetValueOrDefault(Color.Black);

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