我知道这个问题是古老的,但是地狱-我找到了,我认为其他人也可能如此。我正在尝试解决一个相关问题,可能会有一些见识。
您提到了达斯汀·坎贝尔(Dustin Campbell)的WeakEventHandler- 实际上,它确实无法与匿名方法一起使用。当我意识到a)在99%的情况下我需要这样的东西时,我正在尝试摆弄一些东西,他最初的@R_419_2422@案会更安全,并且b)在少数情况下我必须(注意:拥有)而不是“因为lambda太漂亮和简洁了”),如果您有点聪明,就有可能使它起作用。
您的示例似乎完全是一次性的情况,其中有些棘手的问题可能会导致一个相当简洁的@R_419_2422@案。
public static class Linker {
public static void Link(Publisher publisher, Control subscriber) {
// anonymous method references the subscriber only through weak
// references,so its existance doesn't interfere with garbage collection
var subscriber_weak_ref = new WeakReference(subscriber);
// this instance variable will stay in memory as long as the anonymous
// method holds a reference to it we declare and initialize it to
// reserve the memory (also, compiler complains about uninitialized
// variable otherwise)
EventHandler<ValueEventArgs<bool>> handler = null;
// when the handler is created it will grab references to the local
// variables used within, keeping them in memory after the function
// scope ends
handler = delegate(object sender, ValueEventArgs<bool> e) {
var subscriber_strong_ref = subscriber_weak_ref.Target as Control;
if (subscriber_strong_ref != null)
subscriber_strong_ref.Enabled = e.Value;
else {
// unsubscribing the delegate from within itself is risky, but
// because only one instance exists and nobody else has a
// reference to it we can do this
((Publisher)sender).EnabledChanged -= handler;
// by assigning the original instance variable pointer to null
// we make sure that nothing else references the anonymous
// method and it can be collected. After this, the weak
// reference and the handler pointer itselfwill be eligible for
// collection as well.
handler = null;
}
};
publisher.EnabledChanged += handler;
}
}
据传WPF弱事件模式会带来很多开销,因此在这种特殊情况下,我将不使用它。此外,在WinForm应用程序中引用核心WPF库似乎也很繁重。