Question

As soon as I started programming C# (ASP.NET) I was surprised at how restrictive constants were. So far, I haven’t used them much and I feel I missed the concept. How would you guys make use of constants in a typical ASP.NET application?

How would declare a constant struct such as System.Drawing.Color?

Would you guys use readonly when const cannot be used?

I would like to find out how people are using const and readonly and to discuss alternatives if any.

Answer 1

Constants are for defining things in your program that should not change, but need to be referenced multiple times.

const int SLEEP_TIME = 500; //500 MS = .5 Seconds
//Do Something
Thread.Sleep(SLEEP_TIME);
//Do Something else
Thread.Sleep(SLEEP_TIME);
//Do yet another something.

Now if you want to change SLEEP_TIME you can do it in one place.

As for a constant struct I’d usually use an enum

enum State
{
   Stopped = 0,
   Running = 1,
   Paused = 2
}

Readonly is useful for references that need to be assigned once

private static readonly Logger = new TextLogger();

And if you need to change something (ie: initialize something to null, then change it), it by definition can’t be const.