C# 如何为show form创建一个通用函数？

我通常使用以下代码来显示表单：

frmEmployeeManage em = null;
private void ShowEmployee_Click(object sender, EventArgs e)
    {

        if (em == null || em.IsDisposed)
        {
            em = new frmEmployeeManage();
            em.MdiParent = this;
            em.FormBorderStyle = FormBorderStyle.None;
            em.WindowState = FormWindowState.Maximized;
            em.Show();
        }
        else
        {
            em.Activate();
        }
    }

现在我想写一个显示表单的函数。下面的代码我不知道如何将表单类作为参数传递给函数

class CommonService
{
  public static void ShowFrom(Form frmChild, Form frmParent)
  {
    if (frmChild == null || frmParent.IsDisposed)
    {
        frmChild = new Form(); // How passing the form class here?
        frmChild.MdiParent = frmParent;
        frmChild.FormBorderStyle = FormBorderStyle.None;
        frmChild.WindowState = FormWindowState.Maximized;
        frmChild.Show();
    }
    else
    {
        frmParent.Activate();
    }
  }
}

最后，我使用show form函数，如以下示例所示：

frmEmployeeManage em = null;
CommonService.ShowForm(frmEmployee, this);

---

我认为您需要使用

ref

参数：

  public static void ShowFrom<T>(ref T frmChild, Form frmParent) where T : Form, new()
  {
    if (frmChild == null || frmParent.IsDisposed)
    {
        frmChild = new T(); // How passing the form class here?
        frmChild.MdiParent = frmParent;
        frmChild.FormBorderStyle = FormBorderStyle.None;
        frmChild.WindowState = FormWindowState.Maximized;
        frmChild.Show();
    }
    else
    {
        frmParent.Activate();
    }
  }

---

ref

允许您更改方法中参数的值，这些更改也会反映在传入的变量上。

出了什么问题？非常感谢！

frmEmployeeManage em = null;
CommonService.ShowForm(ref em, this);