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    <h2>'The' answer</h2> <p><em>(Read more below if you want to see how I got to this solution)</em></p> <p>Usage, given a control with a vanilla <code>MouseDown</code> event, and a specific <code>EventHandler&lt;ValueEventArgs> ValueEvent</code> event:</p> <pre><code>// for 'vanilla' events SetAnyHandler&lt;Subscriber, MouseEventHandler, MouseEventArgs&gt;( h =&gt; (o,e) =&gt; h(o,e), //don't ask me, but it works*. h =&gt; control.MouseDown += h, h =&gt; control.MouseDown -= h, subscriber, (s, e) =&gt; s.DoSomething(e)); //**See note below // for generic events SetAnyHandler&lt;Subscriber, ValueEventArgs&gt;( h =&gt; control.ValueEvent += h, h =&gt; control.ValueEvent -= h, subscriber, (s, e) =&gt; s.DoSomething(e)); //**See note below </code></pre> <p><em>(*This is a workaround from <a href="http://social.msdn.microsoft.com/Forums/en-US/rx/thread/50d01578-9217-43d3-8ccb-e3f859040a68" rel="nofollow noreferrer">Rx</a>)</em></p> <p>(** it is important to avoid invoking the subscriber object directly here (for instance putting subscriber.DoSomething(e), or invoking DoSomething(e) directly if we are inside the Subscriber class. Doing this effectively creates a reference to subscriber, which completely defeats the object...)</p> <p><strong>Note</strong>: in some circumstances, this CAN leave references to the wrapping classes created for the lambdas in memory, but they only weigh bytes, so I'm not too bothered.</p> <p>Implementation:</p> <pre><code>//This overload handles any type of EventHandler public static void SetAnyHandler&lt;S, TDelegate, TArgs&gt;( Func&lt;EventHandler&lt;TArgs&gt;, TDelegate&gt; converter, Action&lt;TDelegate&gt; add, Action&lt;TDelegate&gt; remove, S subscriber, Action&lt;S, TArgs&gt; action) where TArgs : EventArgs where TDelegate : class where S : class { var subs_weak_ref = new WeakReference(subscriber); TDelegate handler = null; handler = converter(new EventHandler&lt;TArgs&gt;( (s, e) =&gt; { var subs_strong_ref = subs_weak_ref.Target as S; if(subs_strong_ref != null) { action(subs_strong_ref, e); } else { remove(handler); handler = null; } })); add(handler); } // this overload is simplified for generic EventHandlers public static void SetAnyHandler&lt;S, TArgs&gt;( Action&lt;EventHandler&lt;TArgs&gt;&gt; add, Action&lt;EventHandler&lt;TArgs&gt;&gt; remove, S subscriber, Action&lt;S, TArgs&gt; action) where TArgs : EventArgs where S : class { SetAnyHandler&lt;S, EventHandler&lt;TArgs&gt;, TArgs&gt;( h =&gt; h, add, remove, subscriber, action); } </code></pre> <h2>The detail</h2> <p>My starting point was <a href="https://stackoverflow.com/questions/371109/garbage-collection-when-using-anonymous-delegates-for-event-handling/1447619#1447619">Egor</a>'s excellent answer (see link for version with comments):</p> <pre><code>public static void Link(Publisher publisher, Control subscriber) { var subscriber_weak_ref = new WeakReference(subscriber); EventHandler&lt;ValueEventArgs&lt;bool&gt;&gt; handler = null; handler = delegate(object sender, ValueEventArgs&lt;bool&gt; e) { var subscriber_strong_ref = subscriber_weak_ref.Target as Control; if (subscriber_strong_ref != null) subscriber_strong_ref.Enabled = e.Value; else { ((Publisher)sender).EnabledChanged -= handler; handler = null; } }; publisher.EnabledChanged += handler; } </code></pre> <p>What bothered me was that the event is hard coded into the method. So that means for each new event, there is a new method to write.</p> <p>I fiddled around and managed to come up with this generic solution:</p> <pre><code>private static void SetAnyGenericHandler&lt;S, T&gt;( Action&lt;EventHandler&lt;T&gt;&gt; add, //to add event listener to publisher Action&lt;EventHandler&lt;T&gt;&gt; remove, //to remove event listener from publisher S subscriber, //ref to subscriber (to pass to action) Action&lt;S, T&gt; action) //called when event is raised where T : EventArgs where S : class { var subscriber_weak_ref = new WeakReference(subscriber); EventHandler&lt;T&gt; handler = null; handler = delegate(object sender, T e) { var subscriber_strong_ref = subscriber_weak_ref.Target as S; if(subscriber_strong_ref != null) { Console.WriteLine("New event received by subscriber"); action(subscriber_strong_ref, e); } else { remove(handler); handler = null; } }; add(handler); } </code></pre> <p>However the problem with that solution is that it is ONLY generic, it can't handle the standard winforms MouseUp, MouseDown, etc...</p> <p>So I tried to make it even <strong>more</strong> generic:</p> <pre><code>private static void SetAnyHandler&lt;T, R&gt;( Action&lt;T&gt; add, //to add event listener to publisher Action&lt;T&gt; remove, //to remove event listener from publisher Subscriber subscriber, //ref to subscriber (to pass to action) Action&lt;Subscriber, R&gt; action) where T : class { var subscriber_weak_ref = new WeakReference(subscriber); T handler = null; handler = delegate(object sender, R e) //&lt;-compiler doesn't like this line { var subscriber_strong_ref = subscriber_weak_ref.Target as Subscriber; if(subscriber_strong_ref != null) { action(subscriber_strong_ref, e); } else { remove(handler); handler = null; } }; remove(handler); } </code></pre> <p>However, as I hinted <a href="https://stackoverflow.com/questions/371109/garbage-collection-when-using-anonymous-delegates-for-event-handling/1687255#1687255">here</a>, this won't compile, because there is no way of constraining T to be a delegate.</p> <p>At that point, I pretty much gave up. There's no point trying to fight with the C# specs.</p> <p>However, yesterday, I discovered the Observable.FromEvent method from the Reactive framework, I didn't have the implementation, but the usage seemed slightly familiar, and very interesting:</p> <pre><code>var mousedown = Observable.FromEvent&lt;MouseEventHandler, MouseDownEventArgs&gt;( h =&gt; new MouseEventHandler(h), h =&gt; control.MouseDown += h, h =&gt; control.MouseDown -= h); </code></pre> <p>It was the first argument that caught my attention. This is the workaround for the absence of a delegate type constraint. We take of it by passing in the function which will create the delegate.</p> <p>Putting all this together gives us the solution shown at the top of this answer.</p> <h2>Afterthought</h2> <p>I thoroughly recommended taking the time to learn about the reactive framework (or whatever it ends up being called). It is VERY interesting, and slightly mindblowing. I suspect that it will also render questions like this totally redundant.</p> <p>So far, the most interesting stuff I've seen has been the videos on <a href="http://channel9.msdn.com/Search/?Term=reactive" rel="nofollow noreferrer">Channel9</a>.</p>
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    1. POWeak event handler model for use with lambdas
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    1. COSeems a bit more like a blog, but...
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    2. COYeah, I know, I really should start a technical blog, but I rarely have anything interesting to say..
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    3. COThe area you are exploring is far beyond my level of .NET and C# competency at this time, but it is interesting, and thought provoking. Thanks for taking the time to post in detail ! imho this kind of mutant question-answer "dynamic-duo" deserves to be a special kind of StackOverFlow "object" (a "meta-comment" ?). Perhaps suitable for a CodeProject article ? best,
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