Is there a way to define C# strongly-typed aliases of existing primitive types like `string` or `int`?

Question

Perhaps I am demonstrating my ignorance of some oft-used feautre of C# or the .NET framework, but I would like to know if there is a natively-supported way to create a type alia

Answer 1

I made this class to cover identical needs. This one is for the type "int" (I also have one for "string"):

public class NamedInt : IComparable, IEquatable
{
    internal int Value { get; }

    protected NamedInt() { }
    protected NamedInt(int val) { Value = val; }
    protected NamedInt(string val) { Value = Convert.ToInt32(val); }

    public static implicit operator int (NamedInt val) { return val.Value; }

    public static bool operator ==(NamedInt a, int b) { return a?.Value == b; }
    public static bool operator ==(NamedInt a, NamedInt b) { return a?.Value == b?.Value; }
    public static bool operator !=(NamedInt a, int b) { return !(a==b); }
    public static bool operator !=(NamedInt a, NamedInt b) { return !(a==b); }

    public bool Equals(int other) { return Equals(new NamedInt(other)); }
    public override bool Equals(object other) {
        if ((other.GetType() != GetType() && other.GetType() != typeof(string))) return false;
        return Equals(new NamedInt(other.ToString()));
    }
    private bool Equals(NamedInt other) {
        if (ReferenceEquals(null, other)) return false;
        if (ReferenceEquals(this, other)) return true;
        return Equals(Value, other.Value);
    }

    public int CompareTo(int other) { return Value - other; }
    public int CompareTo(NamedInt other) { return Value - other.Value; }

    public override int GetHashCode() { return Value.GetHashCode(); }

    public override string ToString() { return Value.ToString(); }
}

And to consume it in your case:

public class MyStronglyTypedInt: NamedInt {
    public MyStronglyTypedInt(int value) : base(value) {
        // Your validation can go here
    }
    public static implicit operator MyStronglyTypedInt(int value) { 
        return new MyStronglyTypedInt(value);
    }

    public bool Validate() {
        // Your validation can go here
    }
}

If you need to be able to serialize it (Newtonsoft.Json), let me know and I'll add the code.