Please have a look at closures. Delphi anonymous functions are closures. These are created within other functions and as such has access to the scope of that function. This is even so if the anonumous function is assigned to a function parameter that is called after the original function is called. (I will create an … Read more
Lambdas in C# do not have types, until they are used in a context that casts them to a delegate or Expression type. That’s why you cannot do the following: var x = () => “some lambda”; You might enjoy Eric Lippert’s Series on Lambda Expressions vs Anonymous Methods Lambda vs Anon – Part One … Read more
Yes. In .NET 3.5 you can use Func and Action delegates. The Func delegates return a value, while Action delegates return void. Here is what the type names would look like: System.Func<TReturn> // (no arg, with return value) System.Func<T, TReturn> // (1 arg, with return value) System.Func<T1, T2, TReturn> // (2 arg, with return value) … Read more
Unfortunately you can’t. The compiler does not allow you to combine the two “magic” pieces of code. Both involve rewriting your code to support what you want to do: An anonymous method is done by moving the code to a proper method, and lifting local variables to fields on the class with that method An … Read more
Give your instance of the anonymous delegate a name: EventHandler<NewEventArg> handler = delegate(object sender, NewEventArgs e) { //some code }; Subject.NewEvent += handler; Subject.NewEvent -= handler;
Okay, I’ve found that it actually is possible with pointers if in unsafe context: public static class IntEx { unsafe public static Action CreateIncrementer(int* reference) { return () => { *reference += 1; }; } } However, the garbage collector can wreak havoc with this by moving your reference during garbage collection, as the following … Read more
A) ForEach is not LINQ, it is a method on List<T>. B) Just use foreach. C) return will do it. Edit Just to clarify, what you are doing is providing a method that will be called for each entry in the list. return will just apply to the method for that member. The rest of … Read more
Even though I will focus on point one, I begin by giving my 2 cents on the whole issue of performance. Unless differences are big or usage is intensive, usually I don’t bother about microseconds that when added don’t amount to any visible difference to the user. I emphasize that I only don’t care when … Read more
You can break it down into two statements and use the magic of captured variables to achieve the recursion effect: myDelegate build = null; build = delegate(Object bj) { var letters= string.Empty; if (someCondition) return build(some_obj); else string.Empty; };
There’s an MSDN page that talks about this: How to Subscribe to and Unsubscribe from Events Note in particular: If you will not have to unsubscribe to [sic] an event later, you can use the addition assignment operator (+=) to attach an anonymous method to the event. And also: It is important to notice that … Read more