C# namespace alias – what’s the point?

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That is a type alias, not a namespace alias; it is useful to disambiguate – for example, against:

using WinformTimer = System.Windows.Forms.Timer;
using ThreadingTimer = System.Threading.Timer;

(ps: thanks for the choice of Timer ;-p)

Otherwise, if you use both System.Windows.Forms.Timer and System.Timers.Timer in the same file you’d have to keep giving the full names (since Timer could be confusing).

It also plays a part with extern aliases for using types with the same fully-qualified type name from different assemblies – rare, but useful to be supported.

Actually, I can see another use: when you want quick access to a type, but don’t want to use a regular using because you can’t import some conflicting extension methods… a bit convoluted, but… here’s an example…

namespace RealCode {
    //using Foo; // can't use this - it breaks DoSomething
    using Handy = Foo.Handy;
    using Bar;
    static class Program {
        static void Main() {
            Handy h = new Handy(); // prove available
            string test = "abc";            
            test.DoSomething(); // prove available
        }
    }
}
namespace Foo {
    static class TypeOne {
        public static void DoSomething(this string value) { }
    }
    class Handy {}
}
namespace Bar {
    static class TypeTwo {
        public static void DoSomething(this string value) { }
    }
}

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