one event delegating to another event – WPF

http://msdn.microsoft.com/en-us/magazine/dd419663.aspx#id0090030 shows an interesting mini “pattern” of one event (“event-pseudo-field”) delegating all its add/remove logic to another event (pseudo-field).

public event EventHandler CanExecuteChanged{
  add { CommandManager.RequerySuggested += value; }
  remove { CommandManager.RequerySuggested -= value; }
}

This reveals the true meaning of an event member. If an object studentA (of class Student) has an event pseudo field evt2, this field is basically a chain of callbacks (or notification targets, or event handlers). The evt2 field is nothing but a handle to add/remove on this chain.

In many cases, the callbacks run sequentially on the same thread as the event-firing code.

See also http://bigblog.tanbin.com/2010/06/field-like-event-syntax-restrictions.html

发表评论

Fill in your details below or click an icon to log in:

WordPress.com 徽标

您正在使用您的 WordPress.com 账号评论。 登出 /  更改 )

Google photo

您正在使用您的 Google 账号评论。 登出 /  更改 )

Twitter picture

您正在使用您的 Twitter 账号评论。 登出 /  更改 )

Facebook photo

您正在使用您的 Facebook 账号评论。 登出 /  更改 )

Connecting to %s