Does C# support the use of static local variables?

Question

Related: How do I create a static local variable in Java?

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Pardon if this is a duplicate; I was pretty sure this would have been

Answer 1

I haven't seen a good generic solution to this yet so I thought I'd come up with my own. I should note however that for the most part(not always) needing static local variables is probably a sign that you should refactor your code for the reasons that have been stated by many people; state is something for the object not a method. I do however like the idea of limiting the scope of variables.

Without further ado:

public class StaticLocalVariable
{
    private static Dictionary s_GlobalStates = new Dictionary();

    private int m_StateKey;

    public StaticLocalVariable()
    {
        Initialize(default(T));
    }

    public StaticLocalVariable( T value )
    {
        Initialize(value);
    }        

    private void Initialize( T value )
    {
        m_StateKey = new StackTrace(false).GetFrame(2).GetNativeOffset();

        if (!s_GlobalStates.ContainsKey(m_StateKey))
        {                
            s_GlobalStates.Add(m_StateKey, value);
        }
    }

    public T Value
    {
        set { s_GlobalStates[m_StateKey] = value; }
        get { return s_GlobalStates[m_StateKey]; }
    }
}

This isn't thread safe of course but it wouldn't take too much work to make it so. It can be used like so:

static void Main( string[] args )
{
    Console.WriteLine("First Call:");
    Test();
    Console.WriteLine("");
    Console.WriteLine("Second Call:");
    Test();
    Console.ReadLine();
}

public static void Test()
{
    StaticLocalVariable intTest1 = new StaticLocalVariable(0);
    StaticLocalVariable intTest2 = new StaticLocalVariable(1);
    StaticLocalVariable doubleTest1 = new StaticLocalVariable(2.1);
    StaticLocalVariable doubleTest2 = new StaticLocalVariable();

    Console.WriteLine("Values upon entering Method: ");
    Console.WriteLine("    intTest1 Value: " + intTest1.Value);
    Console.WriteLine("    intTest2 Value: " + intTest2.Value);
    Console.WriteLine("    doubleTest1 Value: " + doubleTest1.Value);
    Console.WriteLine("    doubleTest2 Value: " + doubleTest2.Value);

    ++intTest1.Value;
    intTest2.Value *= 3;
    doubleTest1.Value += 3.14;
    doubleTest2.Value += 4.5;

    Console.WriteLine("After messing with values: ");
    Console.WriteLine("    intTest1 Value: " + intTest1.Value);
    Console.WriteLine("    intTest1 Value: " + intTest2.Value);
    Console.WriteLine("    doubleTest1 Value: " + doubleTest1.Value);
    Console.WriteLine("    doubleTest2 Value: " + doubleTest2.Value);            
}


// Output:
// First Call:
// Values upon entering Method:
//     intTest1 Value: 0
//     intTest2 Value: 1
//     doubleTest1 Value: 2.1
//     doubleTest2 Value: 0
// After messing with values:
//     intTest1 Value: 1
//     intTest1 Value: 3
//     doubleTest1 Value: 5.24
//     doubleTest2 Value: 4.5

// Second Call:
// Values upon entering Method:
//     intTest1 Value: 1
//     intTest2 Value: 3
//     doubleTest1 Value: 5.24
//     doubleTest2 Value: 4.5
// After messing with values:
//     intTest1 Value: 2
//     intTest1 Value: 9
//     doubleTest1 Value: 8.38
//     doubleTest2 Value: 9