c# - Single-shot event subscription -

i'm convinced isn't possible, i'm going ask nonetheless.

in order make single-shot subscription events, find myself using (self-invented) pattern:

eventhandler handler=null; handler = (sender, e) => {     someevent -= handler;     initialize(); }; someevent += handler; 

it's quite lot of boiler-plate, , makes resharper whinge modified closures. there way of turning pattern extension method or similar? better way of doing it?

ideally, i'd like:

someevent.oneshot(handler) 

it's not easy refactor extension method, because way can refer event in c# subscribing (+=) or unsubscribing (-=) (unless it's declared in current class).

you use same approach in reactive extensions: observable.fromevent takes 2 delegates subscribe event unsubscribe it. that:

public static class eventhelper {     public static void subscribeoneshot(         action<eventhandler> subscribe,         action<eventhandler> unsubscribe,         eventhandler handler)     {         eventhandler actualhandler = null;         actualhandler = (sender, e) =>         {             unsubscribe(actualhandler);             handler(sender, e);         };         subscribe(actualhandler);     } }  ...  foo f = new foo(); eventhelper.subscribeoneshot(     handler => f.bar += handler,     handler => f.bar -= handler,     (sender, e) => { /* whatever */ });