// C# Eval Expression

// Doc: https://eval-expression.net/register-unregister

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// @nuget: Z.Expressions.Eval

​

/*

## RegisterDefaultAliasSafe

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The RegisterDefaultAliasSafe method register types, members and extensions methods of all safe types consired safe (Array, Dictionary, List, Tuple, etc.). You can find the complete list here:

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In this example, we will unregister all types and then register only types included in the `RegisterDefaultAliasSafe` methods. First, we will create a dictionary that is part of the registered types. Then we will try to create a `DataTable` but it will fail as our library exclude it by default as we flag this object unsafe due to method such as `Load` and `WriteXml`.

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See more: https://eval-expression.net/register-unregister

*/

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using System;

using Z.Expressions;

​

public class Program

{

    public static void Main()

    {

        // Global Context: EvalManager.DefaultContext.RegisterDefaultAliasSafe();

        var context = new EvalContext();

        context.UnregisterAll();

        context.RegisterDefaultAliasSafe();

        // 1 - You can access the Dictionary object since the type has been registered in the RegisterDefaultAliasSafe

        var r1 = context.Execute<int>(@"var dict = new Dictionary<string, object>(); return dict.Count;");

        Console.WriteLine("1 - Result: " + r1);

        try

        {

            var fail = context.Execute<int>("var dt = new DataTable(); return dt.Rows.Count;");

        }

        catch(Exception ex)

        {

            // 2 - However, you cannot access the DataTable because we excluded this type due to methods such as `Load`  and `WriteXml`

            Console.WriteLine("2 - Exception: " + ex.Message);

        }

    }

}