C#

If (_isOpened)
 return;

private bool _isOpen;

public class FormManager
    {
        // Main Form
        private MainForm mainForm;

        public FormManager(MainForm mainForm)
        {
            this.mainForm = mainForm;
        }

        public virtual System.Windows.Forms.Form GetForm(Type type, object[] args)
        {
            return GetMDIForm(type, args);
        }

        private ChildForm GetChildMDIForm(Type type)
        {
            // Try to get form of type 'type' from MdiChildren in mainForm
            for (int i = 0; i < mainForm.MdiChildren.Length; i++)
            {
                if (mainForm.MdiChildren[i].GetType().Equals(type))
                {
                    return (ChildForm)mainForm.MdiChildren[i];
                }
            }
            return null;
        }
        public virtual ChildForm GetMDIForm(Type type, object[] args)
        {
            ChildForm form = null;
            bool allowMultiple = false;

            // Attribute to decide whether multiple instance of form is allowed.
            object[] attributes = type.GetCustomAttributes(typeof(ChildFormAttribute), false);
            if (attributes.Length > 0)
            {
                allowMultiple = ((ChildFormAttribute)attributes[0]).AllowMulti;
            }

            if (!allowMultiple) // Not allow to create multiple
            {
                //Try to get from MDI Content
                form = GetChildMDIForm(type);
            }

            if (form == null)
            {
                form = CreateChildMDIForm(type, args);
                if (form != null)
                {
                    form.MdiParent = mainForm;
                    form.WindowState = FormWindowState.Maximized;
                    form.Show()
                }
                else
                {
                    throw new Exception(string.Format("Unable to create form of type '{0}'", type.ToString()));
                }
            }
            else
            {
                form.BringToFront();
            }

            return form;
        }
        private ChildForm CreateChildMDIForm(Type type, object[] args)
        {
            // Try to create a new form with args
            ConstructorInfo ci = type.GetConstructor(System.Type.EmptyTypes);
            ChildForm form = (ChildForm)ci.Invoke(args);
            return form;
        }

        public void ShowRole()
        {
            // Singleton class for opening new form or bring existing form to front
            Wine.Global.FormManager.Instance.GetForm(typeof(Wine.UI.Role), null);
        }

    }

    [ChildFormAttribute(false)] //<---- Use Attribute to indicate this form can not be multiple
    public partial class Role : ChildForm
    {
        public Role()
            : base()
        {
            InitializeComponent();
        }

    }

    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
    public class ChildFormAttribute : System.Attribute
    {
        private bool allowMulti;
        public bool AllowMulti
        {
            get
            {
                return allowMulti;
            }
        }

        public ChildFormAttribute(bool allowMulti)
        {
            this.allowMulti = allowMulti;
        }
    }

George_George wrote:

What means the assemblies?

George_George wrote:

For the following sample, why creates two XMLSerializer instances, one is s and the other is ser?