What exactly do you mean by thread-safe? You certainly shouldn’t change the dictionary while you’re iterating over it, whether in the same thread or not. If the dictionary is being accessed in multiple threads in general, the caller should take out a lock (the same one covering all accesses) so that they can lock for … Read more
UPDATE 2022-Oct Reading this answer after all these years, I felt the original tone was too harsh, and I came off as an a-hole. So I soften the tone a bit. Sorry to resurrect this from the dead, but reading the accepted answer by Daniel, and then testing it myself I though that at least … Read more
Try this: val x: String = list.mkString This syntax: for (i <- list) yield i is syntactic sugar for: list.map(i => i) and will thus return an unchanged copy of your original list.
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
I am just left with a leaked connection. No, you’re not. When does the finally get invoked? When the IEnumerator<T> is disposed, which First is going to do after getting the first item of the sequence (just like everyone should be doing when they use an IEnumerator<T>). Now if someone wrote: //note no `using` block … Read more
Short version – no, that isn’t possible via an iterator block; the longer version probably involves synchronized queue/dequeue between the caller’s iterator thread (doing the dequeue) and the parallel workers (doing the enqueue); but as a side note – logs are usually IO-bound, and parallelising things that are IO-bound often doesn’t work very well. If … Read more
Here is a code snippet, which works for me (I did not reach the error condition). while (true) { T ret = null; try { if (!enumerator.MoveNext()) { break; } ret = enumerator.Current; } catch (Exception ex) { // handle the exception and end the iteration // probably you want it to re-throw it break; … Read more
You can get a reference to the Enumerator, using the GetEnumerator method, then you can use the MoveNext() method to move on, and use the Current property to access your elements: var enumerator = getInt().GetEnumerator(); while(enumerator.MoveNext()) { int n = enumerator.Current; Console.WriteLine(n); }
When you call GetAllAnimals it doesn’t actually execute any code until you enumerate the returned IEnumerable in a foreach loop. The dataContext is being disposed as soon as the wrapper method returns, before you enumerate the IEnumerable. The simplest solution would be to make the wrapper method an iterator as well, like this: public static … Read more
But what if you were building a collection yourself? In general, iterators can be used to lazily generate a sequence of objects. For example Enumerable.Range method does not have any kind of collection internally. It just generates the next number on demand. There are many uses to this lazy sequence generation using a state machine. … Read more