Local static readonly fields

[mariusz96]

Local static readonly fields

Currently it is possible to declare static readonly fields inside classes:

public class MyClass
{
    private static readonly DateTime StaticReadOnlyField1 = new(2021, 1, 1);
    private static readonly List<DateTime> StaticReadOnlyFields2 = [new DateTime(2022, 1, 1), new DateTime(2023, 1, 1)];

    public void MyMethod1()
    {
        // Use StaticReadOnlyField1...
    }

    public void MyMethod2()
    {
        // Use StaticReadOnlyFields2...
    }
}

however they are also useful inside methods:

public class MyClass
{
    public void MyMethod1()
    {
        static readonly DateTime StaticReadOnlyField1 = new(2021, 1, 1);
        // Use StaticReadOnlyField1...
    }

    public void MyMethod2()
    {
        static readonly List<DateTime> StaticReadOnlyFields2 = [new DateTime(2022, 1, 1), new DateTime(2023, 1, 1)];
        // Use StaticReadOnlyFields2...
    }
}

because they:

• improve readability
• often end up being used only once
• reduce scope

and declaring them without static readonly keyword wastes computer resources

Local constants

They are analogous to local constants which exist today:

[MSDN] The following example demonstrates how to declare a local constant:

public class SealedTest
{
    static void Main()
    {
        const int C = 707;
        Console.WriteLine($"My local constant = {C}");
    }
}
// Output: My local constant = 707

[HaloFour]

See: #832