Is it possible to declare C# object reference parameter inline within a method call?

I have a C# application. I was wondering if there was anyway I can initialize a ref object parameter inline?

Consider the following code block:

public class CacheTest : Dictionary<string, string> { }

static void Main(string[] args)
{
    CacheTest cache = null;

    for (int index = 1; index <= 2; index++)
    {
        var result1 = TestClass.DoSomething(ref cache, $"key{index}");
        Console.WriteLine($"Key: {index}  Value{result1}");
    }
}

public static class TestClass
{
    public static string DoSomething(ref CacheTest cache, string key)
    {
        if (cache == null)
        {
            cache = new CacheTest()
            {
                { "key1", "value1" },
                { "key2", "value2" }
            };
        }

        return cache[key];
    }
}

In the preceding code block, I am declaring the variable cache before I reference it as a ref in the DoSomething() method call.

Is there any way that I can do this in a single line either through use of ref or out?

Something like this:

var result1 = TestClass.DoSomething(ref CacheTest cache, $"key{index}")

I know it’s a stretch, but I’ve got to make changes to existing code in a 100 places and it would nice to provide a tighter implementation. I would want to initialize only on the 1st call.

>Solution :

No, it is not possible to initialize a ref or out parameter inline in C# based on the code you provided above. The ref and out keywords are used to pass arguments by reference, which allows the called method to modify the original variable. In order to use a ref or out parameter, you must declare the variable before passing it to the method.

In your example, you have correctly declared the variable cache before passing it to the DoSomething() method as a ref parameter. There is no way to combine the declaration and the method call into a single line using the ref or out keyword.

Follow the two code examples I gave you, that is the way 😉