限制基类参数的类型

Question

我有这样的代码:

public static void ToUpperCase(params Control[] controls)
{
    foreach (Control oControl in controls)
    {
        if (oControl is TextBox)
        {
            oControl.TextChanged += (sndr, evnt) =>
            {
                TextBox txtControl = sndr as TextBox;
                int pos = txtControl.SelectionStart;
                txtControl.Text = txtControl.Text.ToUpper();
                txtControl.SelectionStart = pos;
            };
        }
        else if (oControl is ComboBox)
        {
            oControl.TextChanged += (sndr, evnt) =>
            {
                ComboBox cmbControl = sndr as ComboBox;
                int pos = cmbControl.SelectionStart;
                cmbControl.Text = cmbControl.Text.ToUpper();
                cmbControl.SelectionStart = pos;
            };
        }
        else throw new NotImplementedException(oControl.GetType().DeclaringType.ToString() + " is not allowed.");
    }
}

我想限制params Control[] controls只接受一个TextBox和一个ComboBox类型.

我的代码在C#,框架4,在VS2010Pro中构建,项目在WinForms中.

请帮忙.提前致谢.

Answer 1

你不能 - 他们没有一个好的共同祖先.

你可以(也可能应该)做的是对你的方法进行两次重载,它们带有每个参数:

public static void ToUpperCase(params TextBox[] controls)
{
    foreach (TextBox oControl in controls)
        oControl.TextChanged += (sndr, evnt) =>
        {
            TextBox txtControl = sndr as TextBox ;
            int pos = txtControl.SelectionStart;
            txtControl.Text = txtControl.Text.ToUpper();
            txtControl.SelectionStart = pos;
        };
}

public static void ToUpperCase(params ComboBox[] controls)
{
    foreach (ComboBoxControl oControl in controls)
        oControl.TextChanged += (sndr, evnt) =>
        {
            ComboBox txtControl = sndr as ComboBox;
            int pos = txtControl.SelectionStart;
            txtControl.Text = txtControl.Text.ToUpper();
            txtControl.SelectionStart = pos;
        };
}