Question

Why can’t you create a generic indexer in .NET?

the following code throws a compiler error:

public T this<T>[string key] {     get => /* Return generic type T. */ } 

Does this mean you can’t create a generic indexer for a generic member collection?

Answer 1

The only thing I can think of this can be used is something along these lines:

var settings = ConfigurationSection.AppSettings; var connectionString = settings<string>['connectionString']; var timeout = settings<int>['timeout']; 

But this doesn’t actually buy you anything. You’ve just replaced round parentheses (as in (int)settings['timeout']) with angle brackets, but received no additional type safety as you can freely do

var timeout = settings<int>['connectionString']; 

If you have something that’s strongly but not statically typed, you might want to wait until C# 4.0 with its dynamic keyword.