Question

I am using .NET 2.0 & C# to develop a WinForm Mdi application. It will have a Main Window and a lot of mdi windows. I am thinking I should use which design pattern to manage mdi windows. Because I want only one instance for each window, if window is existed, I will show it on top, & otherwise I will create and show it.

Note: a mdi window is opened from Menus of Main Window or open from another mdi window. An example is very good.

Update: Menu’s status is depended on mdi window’s status. Ex: If Window ‘A’ is openned -> menu ‘A’ -> disabled. When window ‘A’ is closed -> I update menu ‘A’ status to Enabled.

Thanks.

Answer 1

I dont think you will find one pattern to solve the problem, but will be a collaboration of pattern. The links provided by Josh are interesting read.

A simple suggestion based on GoF pattern will be as below:

• Use Command pattern to handle your
  menu click event
• Use Factory pattern to create your window. You can custom your factory
  so that it creates only single
  instance of the window, using
  approach from Singleton pattern
• Use Subject-Observer pattern for the menu state. The MDI child window
  will be the subject and you will need
  to structure your code so that you
  can embedded observer logic in your
  menu controller.