using System;

using System.IO;

using System.Diagnostics;

using System.Linq.Expressions;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var stopwatch = new Stopwatch();

        //var a = new A();

        Expression<Func<A, object>> propertyExpression;

        //Console.WriteLine(ExpressionUtils.GetPropertyNameFromExpression(propertyExpression));

        // -----------

        propertyExpression = x => x.PropStr1;

        //ExpressionUtils.GetPropertyNameFromExpression(propertyExpression); // warm up (prvni volani je dlouhe a pak uz ok)

        stopwatch.Start();

        for (int i = 0; i < 99999999; i++)

        {

            //int len = "PropStr1".Length;

            //int len = nameof(A.PropStr1).Length;

            //int len = ExpressionUtils.GetPropertyNameFromExpression(propertyExpression).Length;

            var x = propertyExpression;

        }

        stopwatch.Stop();

        Console.WriteLine(stopwatch.Elapsed);

    }

}

​

class A

{

    public string PropStr1 { get; private set; } = "AAA";

    public string PropStr2 { get; private set; } = "BBB";

    public string PropStr3 { get; private set; } = "CCC";

}

​

public static class ExpressionUtils

{

    public static string GetPropertyNameFromExpression<TModel, TPropertyX>(Expression<Func<TModel, TPropertyX>> propertyExpression)

    {

        return ((MemberExpression)propertyExpression.Body).Member.Name;

    }

​

    public static Type GetPropertyTypeFromExpression<TModel, TPropertyX>(Expression<Func<TModel, TPropertyX>> propertyExpression)

    {

        return ((MemberExpression)propertyExpression.Body).Type;

    }

}