// C# Eval Expression

// Doc: https://eval-expression.net/options

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// @nuget: Z.Expressions.Eval

​

/*

## AllowAddSubtractOperatorToCollection

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The AllowAddSubtractOperatorToCollection option lets you get or set if the minus characters `-` can be used to remove an item from a list. In other words, doing `list - 200` will behave like `list.Remove(200)`. By default, the AllowAddSubtractOperatorToCollection value is `false`. 

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In this example, we will add an item to a list and remove it. We will do it for a list of `int`, a list of `string`, and a list of `entity`.

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See more: https://eval-expression.net/options

*/

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using System;

using System.Collections.Generic;

using Z.Expressions;

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public class Program

{

    public static void Main()

    {

        // Global Context: EvalManager.DefaultContext.AllowAddSubtractOperatorToCollection = true;

        var context = new EvalContext();

        context.AllowAddSubtractOperatorToCollection = true;

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        // using Add and Substract with a list of `int`

        {

            var list = new List<int>();

            Console.WriteLine("1 - list count initial:" + list.Count);

            context.Execute("list + 1", new { list });

            Console.WriteLine("2 - list count after add:" + list.Count);

            context.Execute("list - 1", new { list });

            Console.WriteLine("3 - list count aftert substract:" + list.Count);

        }

        // using Add and Substract with a list of `string`

        {

            var list = new List<string>();

            Console.WriteLine("4 - list count initial:" + list.Count);

            context.Execute("list + 'C# Eval Expression'", new { list });

            Console.WriteLine("5 - list count after add:" + list.Count);

            context.Execute("list - 'C# Eval Expression'", new { list });

            Console.WriteLine("6 - list count aftert substract:" + list.Count);

        }

        // using Add and Substract with a list of `Entity`

        {

            var list = new List<Entity>();

            Console.WriteLine("7 - list count initial:" + list.Count);

            var entity = new Entity();

            context.Execute("list + entity", new { list, entity });

            Console.WriteLine("8 - list count after add:" + list.Count);

            context.Execute("list - entity", new { list, entity });

            Console.WriteLine("9 - list count aftert substract:" + list.Count);

        }

    }

    public class Entity

    {

        public int EntityID { get; set; }

    }

}

​

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