Why .NET doesn't have built-in Observer pattern like Java? [closed]

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I wonder why .NET framework doesn't have pair (Observer/Observable) interfaces similar to Java's feature?

EDIT:开发者_开发百科 yes i know about events and delegates but using those interfaces is a simple and bookish approach of this DP isn't it?

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In .NET 4 it does: System.IObservable<T> and System.IObserver<T> (which are a Dual of IEnumerable<T> and IEnumerator<T>). Look at the Reactive Extensions (Rx) project for compositional use of these interfaces with asynchronous events.

More generally, the Observer pattern is better served in .NET with events.

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Because .NET has actual events and delegates. Java lacks these basic constructs and has to resort to ugly hacks (your Observable interface) to pass "method pointers" around.

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You can achieve the same thing with events and spaghetti code and they will drive you crazy trying to cleanup after them as they lock themselves into your non-disposable memory blocks.

If you don't yet have .Net 4, use the well know observer pattern and type it out the old-fashioned way - by hand.

The observer pattern is not simply writing events longhand, it's the basis for re-usable and extendable code. It is also a more decoupled and elegant approach to your solution.

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You can achieve the same sort of thing with Events. Also you can easily implement your own Observer pattern. It has to be one of the easiest patterns to implement: http://en.wikipedia.org/wiki/Observer_pattern

As for the why part. Not sure.

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Where have you been. It is called events and delegates. Yes, it is a hack, but it works and more people prefer to use the language built in features over a design pattern you must type in yourself. The language feature is already debugged and ready to go.