C# Cannot use ref or out parameter inside an anonymous method body

Question

I\'m trying to create a function that can create an Action that increments whatever integer is passed in. However my first attempt is giving me an error \"cannot use ref or

Answer 1

It might have been a useful feature for the runtime to allow the creation of variable references with a mechanism to prevent their persistence; such a feature would have allowed an indexer to behave like an array (e.g. so a Dictionary could be accessed via "myDictionary[5].X = 9;"). I think such a feature could have been provided safely if such references could not be downcast to other types of objects, nor used as fields, nor passed by reference themselves (since anyplace such a reference could be stored would go out of scope before the reference itself would). Unfortunately, the CLR does not provide such a feature.

To implement what you're after would require that the caller of any function which uses a reference parameter within a closure must wrap within a closure any variable it wants to pass to such a function. If there were a special declaration to indicate that a parameter would be used in such a fashion, it might be practical for a compiler to implement the required behavior. Maybe in a .net 5.0 compiler, though I'm not sure how useful that would be.

BTW, my understanding is that closures in Java use by-value semantics, while those in .net are by-reference. I can understand some occasional uses for by-reference semantics, but using reference by default seems a dubious decision, analogous to the use of default by-reference parameter-passing semantics for VB versions up through VB6. If one wants to capture the value of a variable when creating a delegate to call a function (e.g. if one wants a delegate to call MyFunction(X) using the value of X when the delegate is created), is it better to use a lambda with an extra temp, or is it better to simply use a delegate factory and not bother with Lambda expressions.