// C# Eval Expression

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

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// @nuget: Z.Expressions.Eval

​

/*

## Execute Async

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The C# Eval library supports `Async` but has no `ExecuteAsync` method.

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Adding `Async` methods doesn't make sense, as your non-async code will not magically start to be executed asynchronously. A code runs asynchronously when you call a method that supports async and returns a `Task` or `Task<TResult>`.

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To execute `Async`, you have 2 choices:

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1. **Return a task:** `Eval.Execute<Task>(code)` or `Eval.Execute<Task<Result>>(code)`

2. **Handle the task** using `await` in the code

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1 - If you **return a task** (`Eval.Execute<Task>(code)` or `Eval.Execute<Task<Result>>(code)`), you need to handle the task with `await` outside the code you want to execute dynamically 

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2 - If you **handle the task**, you need to use `await` inside the code you want to execute dynamically

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

*/

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using System;

using System.IO;

using System.Threading.Tasks;

using Z.Expressions;

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public class Program

{

    public static async Task Main()

    {

        var fileName = "myfile.txt";

        await File.WriteAllTextAsync(fileName, "C# Eval Expression from ZZZ Projects");

        // 1. **Return a task:** `Eval.Execute<Task>(code)` or `Eval.Execute<Task<Result>>(code)`

        {

            var task = Eval.Execute<Task<string>>("File.ReadAllTextAsync(fileName)", new { fileName });     

            var text1 = await task;

            Console.WriteLine(text1);

        }

​

        // 2. **Handle the task** using `await` in the code

        {

            var text2 = Eval.Execute<string>("await File.ReadAllTextAsync(fileName)", new { fileName });

            Console.WriteLine(text2);

        }

    }

}