Roslyn Scripting Add Namespace to Evaluation

In the EvaluateAsync method, you can evaluate a member, as shown below.

static async Task EvaluateExample3()
{
    var result = await CSharpScript.EvaluateAsync("System.Console.WriteLine(System.DateTime.Now)");
}

As you can see, we specified a member with a fully qualified path. Now, if you have a lot of code to evaluate or you need to use the same member several times, it will be very difficult to specify a fully qualified path again and again.

The CSharpScript.EvaluateAsync method also provides an overload that also takes ScriptOptions as a parameter.

static async Task EvaluateExample4()
{
    var result = await CSharpScript.EvaluateAsync("Console.WriteLine(DateTime.Now)", 
        ScriptOptions.Default.WithImports("System"));
}

The ScriptOptions.Default.WithImports("System") adds using System; to the script.

Sometimes, you will need to add class members to the script to use directly without calling their class name. For example, if you are using System.Math.Sqrt several times, and now you want to use just Sqrt. Like adding references, if you use WithImports with a class name, it adds using static System.Math;.

static async Task EvaluateExample5()
{
    double result = await CSharpScript.EvaluateAsync<double>("Sqrt(64)",
        ScriptOptions.Default.WithImports("System.Math"));

    Console.WriteLine(result);
}

You can also add references very easily with WithReferences method.

static async Task EvaluateExample6()
{
    var result = await CSharpScript.EvaluateAsync("System.Net.Dns.GetHostName()",
        ScriptOptions.Default.WithReferences(typeof(System.Net.Dns).Assembly));
    Console.WriteLine(result);
}