Custom TextBox control: AppendLine

Question

Is there any way to improve this simple addition to the textbox control: appending a new line?

class CustomTextBox : TextBox
{
    public void AppendLine(string textData)
    {
        if (this.Text.EndsWith(Environment.NewLine) || this.Text == "")
        {
            this.AppendText(textData);
        }
        else
        {
            this.AppendText(Environment.NewLine + textData);
        }
    }  
}

Answer 1

When I am thinking about changing / enhancing some code, I have usually two things (regarding the code for review) in mind:

1. Whenever there is some method that gets called in every if-else / switch-case, think about using some variable to make it single call. (This includes same method on different objects of common type - not aplicable to this case, but for the record)
2. Check all conditions (and variables), if they are really required. (This includes joined conditions, when one renders to be redundant because of another already met. Sometimes I see variables that are used to avoid goto, but it turns out it can be done without both by reorganizing it - again not aplicable to this code review, but for the check-list)

My final solution would look like this:

class CustomTextBox : TextBox {
    public void AppendLine(string textToAppend) {
        string current = this.Text;
        if (current.Length > 0
        && !current.EndsWith(Environment.NewLine))
            textToAppend = Environment.NewLine + textToAppend;
        this.AppendText(textToAppend);
    }
}

EDIT: I have deleted all redundant / wrong parts. The check for empty text is needed, and TextLength is a property of WinForms TextBox, not the one in WPF.

Answer 2

I don't care for empty quotes designating an empty string. It should be replaced with String.Empty. It simply clarifies your intention and leaves no ambiguity that you perhaps forgot to put something in the quotes, or maybe even meant to put a space in there. Otherwise, I feel this is very simple and solid.