Why does ConcurrentDictionary.TryRemove require a second out argument?

Question

I only want to remove a value.. I don't need to use the variable afterwards. Why not include an overload where this second parameter was not required?

Do I really have to just store it in a temporary local variable, not use it, and have the garbage collector collect it when the method ends? Seems rather silly..

The function: http://msdn.microsoft.com/en-us/library/dd287129.aspx

Answer 1

C#7 added discard syntactic sugar

So now you can write:

dictionary.TryRemove(entry.Key, out _);  

Reference

We allow "discards" as out parameters as well, in the form of a _, to let you ignore out parameters you don’t care about:

p.GetCoordinates(out var x, out _); // I only care about x

Answer 2

You can create exactly the method you want:

public static class ConcurrentDictionaryEx {   public static bool TryRemove<TKey, TValue>(     this ConcurrentDictionary<TKey, TValue> self, TKey key) {     TValue ignored;     return self.TryRemove(key, out ignored);   } } 

UPDATE: Or, as Dialecticus mentioned in the comments, just use Remove. But note that, since it's an explicit interface implementation, you'll need a reference to an IDictionary<TKey, TValue>, which leads you back to creating an extension method if you want to avoid casting a ConcurrentDictionary<TKey, TValue> reference:

public static class ConcurrentDictionaryEx {   public static bool Remove<TKey, TValue>(     this ConcurrentDictionary<TKey, TValue> self, TKey key) {       return ((IDictionary<TKey, TValue>)self).Remove(key);   } }