C# static variables not persisting?

Question

Below is my code snippet, the variable "_lastError" doesn't seem to persist after it is set then accessed elsewhere.

Can anyone give a heads up on what I missed or done incorrectly? I've debugged the program, setting a breakpoint at both the getter and the private setter. Nothing else seems to be accessing nor modifying the value of "_lastError" other than where it was intended to.

class Utils
{
    private static string _lastError;
    public static string LastError
    {
        get
        {
            string lastError = Utils._lastError;
            Utils._lastError = string.Empty;
            return lastError;
        }

        private set
        {
            Utils._lastError = value;
        }
    }

    public static void Foo()
    {
        try { // .... // }
        catch (Exception ex)
        {
            Utils.LastError = ex.Message;
        }
    }
}

Your `get` method is clearing it? `Utils._lastError = string.Empty;` — James Thorpe, Aug 05 '15 at 15:25
Only hovering over the property while debugging will already reset it... — Patrick Hofman, Aug 05 '15 at 15:25
Please describe what your class Utils should do. At the moment, it doesn't look good... You have private setter and the only set is in the getter? Something smells a lot. — Dimitar Tsonev, Aug 05 '15 at 15:37
@JamesThorpe: It was intended. I meant for it to clear the value once it is referenced. — xefrog, Aug 05 '15 at 15:49
That's the very reason why it's not persisting though. The first time it's read anywhere (including in the debugger as per @Patrick's comment), it's going to get cleared. — James Thorpe, Aug 05 '15 at 15:50
@PatrickHofman: Yes! You're right. That must be why. Thank you! — xefrog, Aug 05 '15 at 15:51
@DimitarTsonev: It was intended for the variable to be set only by the Utils class. — xefrog, Aug 05 '15 at 15:51

score 0 · Accepted Answer · answered Aug 05 '15 at 15:47

If the intended behavior is to hold the last error until it's accessed once, then the way you describe it acting is expected.

If the intended behavior is to hold onto the last error until another newer error overwrites it, James's point is important to remember. You're clearing the static value once it's accessed, which as Patrick pointed out affects your view in the debugger. The debugger enumerates all properties, because properties aren't intended to have side effects like wiping out the data that backs them.

C# static variables not persisting?

1 Answers1