C# Eval - My First Option - Use option for safe mode

CSharp · Console

/Program.cs

// C# Eval Expression
// Doc: https://eval-expression.net/my-first-evaluation

// @nuget: Z.Expressions.Eval

/*
## Use Option for Safe Mode

The [Safe Mode](/options#safemode) ensures that only members and types registered can be used for the expression.

To use safe mode, we recommend:
- A local or static context
- Unregistering all types first
- Limiting the maximum number of loops with the [MaxLoopIteration](/options#maxloopiteration) option
- Setting the `SafeMode` option to true
- Registering only what you want the user to be able to use

For example, we will demonstrate how easy it is to configure options in the C# Eval Expression library:

See more: https://eval-expression.net/my-first-evaluation
*/

using System;
using System.Collections.Generic;
using Z.Expressions;

public class Program
{
	public static void Main()
	{
		var evalContext = new EvalContext();
		evalContext.UnregisterAll();
		evalContext.MaxLoopIteration = 5;
		evalContext.SafeMode = true;
		
		evalContext.RegisterMember(typeof(System.Math));
		var r1 = evalContext.Execute("Math.Min(1, 2)");
		Console.WriteLine("1 - Result: " + r1);
		
		try
		{
			// `List` is no longer registered, so it cannot be used
			var r2 = evalContext.Execute("new List<int>()");
		}
		catch(Exception ex)
		{
			Console.WriteLine("Cannot use `List` exception: " + ex.Message);
		}
	}
}