using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication21
{
    [MyTest1(Name = "Name1", Description = "Desc1")]
    [MyTest2(Value1=1, Value2 = new double[] { 1, 2, 3})]
    class Program
    {
        static void Main(string[] args)
        {
            var p = new Program();
            var name = p.A<MyTest1Attribute>().Name;
            var desc = p.A<MyTest1Attribute>().Description;
            var val1 = p.A<MyTest2Attribute>().Value1;
            var val2 = p.A<MyTest2Attribute>().Value2;

            var myClassObj = new MyTestClass();
            name = myClassObj.A<MyTest1Attribute>().Name;
            desc = myClassObj.A<MyTest1Attribute>().Description;
        }
    }

    public static class MyHelper
    {
        public static dynamic A<TAttr>(this object myObj)
        {
            return myObj.GetType()
                .GetCustomAttributes(typeof(TAttr), true)
                .FirstOrDefault();
        }
    }

    [MyTest1(Name="Name1", Description="Desc1")]
    public class MyTestClass
    { 
    }

    [AttributeUsage(AttributeTargets.Class)]
    public class MyTest1Attribute : Attribute
    {
        public string Name { get; set; }
        public string Description { get; set; }

        public MyTest1Attribute()
        {
        }
    }

    [AttributeUsage(AttributeTargets.Class)]
    public class MyTest2Attribute : Attribute
    {
        public int Value1 { get; set; }
        public double[] Value2 { get; set; }

        public MyTest2Attribute()
        {
        }
    }
}

using System;
using System.Collections.Generic;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication21
{
    [MyTest1(Name = "Name1", Description = "Desc1")]
    [MyTest2(Value1=1, Value2 = new double[] { 1, 2, 3})]
    class Program
    {
        static void Main(string[] args)
        {
            var p = new Program();
            var name = p.A<MyTest1Attribute>().Name;
            var desc = p.A<MyTest1Attribute>().Description;
            var val1 = p.A<MyTest2Attribute>().Value1;
            var val2 = p.A<MyTest2Attribute>().Value2;

            var mco = new MyTestClass();
            name = mco.A<MyTest1Attribute>().Name;
            desc = mco.A<MyTest1Attribute>().Description;

            val1 = mco.P(x => mco.MyProp1).A<MyTest2Attribute>().Value1;
            val2 = mco.P(x => mco.MyProp1).A<MyTest2Attribute>().Value2;
        }
    }

    public static class MyHelper
    {
        public static dynamic A<TAttr>(this object myObj)
        {
            return myObj.GetType()
                .GetCustomAttributes(typeof(TAttr), true)
                .FirstOrDefault();
        }

        public static dynamic A<TAttr>(this MemberInfo memberInfo)
        {
            return memberInfo
                .GetCustomAttributes(typeof(TAttr), true)
                .FirstOrDefault();
        }

        public static MemberInfo P<T, K>(this T myObj, Expression<Func<T, K>> propSelector)
        {
            if (propSelector.Body.NodeType != ExpressionType.MemberAccess)
                throw new ArgumentException("Это не селектор члена класса");

            MemberExpression memberAccess = propSelector.Body as MemberExpression;

            if (memberAccess.Member.MemberType != MemberTypes.Property)
                throw new ArgumentException("Это не селектор проперти");

            return memberAccess.Member;
        }
    }

    [MyTest1(Name="Name1", Description="Desc1")]
    public class MyTestClass
    {
        [MyTest2(Value1 = 7, Value2 = new double[] { 7, 8, 9 })]
        public string MyProp1 { get; set; }
    }

    [AttributeUsage(AttributeTargets.Class)]
    public class MyTest1Attribute : Attribute
    {
        public string Name { get; set; }
        public string Description { get; set; }

        public MyTest1Attribute()
        {
        }
    }

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Property)]
    public class MyTest2Attribute : Attribute
    {
        public int Value1 { get; set; }
        public double[] Value2 { get; set; }

        public MyTest2Attribute()
        {
        }
    }
}

using System;
using System.Collections.Generic;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication21
{
    [MyTest1(Name = "Name1", Description = "Desc1")]
    [MyTest2(Value1=1, Value2 = new double[] { 1, 2, 3})]
    class Program
    {
        static void Main(string[] args)
        {
            var p = new Program();
            var name = p.A<MyTest1Attribute>().Name;
            var desc = p.A<MyTest1Attribute>().Description;
            var val1 = p.A<MyTest2Attribute>().Value1;
            var val2 = p.A<MyTest2Attribute>().Value2;

            var mco = new MyTestClass();
            name = mco.A<MyTest1Attribute>().Name;
            desc = mco.A<MyTest1Attribute>().Description;

            val1 = mco.M(x => mco.MyProp1).A<MyTest2Attribute>().Value1;
            val2 = mco.M(x => mco.MyProp1).A<MyTest2Attribute>().Value2;

            val1 = mco.M(x => mco.HelloWorld1()).A<MyTest2Attribute>().Value1;
            val2 = mco.M(x => mco.HelloWorld1()).A<MyTest2Attribute>().Value2;

            val1 = mco.M(x => mco.HelloWorld2(string.Empty)).A<MyTest2Attribute>().Value1;
            val2 = mco.M(x => mco.HelloWorld2(string.Empty)).A<MyTest2Attribute>().Value2;
        }
    }

    public static class MyHelper
    {
        public static TAttr A<TAttr>(this object myObj)
        {
            return (TAttr)myObj.GetType()
                .GetCustomAttributes(typeof(TAttr), true)
                .FirstOrDefault();
        }

        public static TAttr A<TAttr>(this MemberInfo memberInfo)
        {
            return (TAttr)memberInfo
                .GetCustomAttributes(typeof(TAttr), true)
                .FirstOrDefault();
        }

        public static MemberInfo M<T, K>(this T myObj, Expression<Func<T, K>> propSelector)
        {
            if ((propSelector.Body.NodeType != ExpressionType.MemberAccess) &&
                (propSelector.Body.NodeType != ExpressionType.Call))
                throw new ArgumentException("Это не селектор члена класса");

            MemberExpression memberAccess = propSelector.Body as MemberExpression;

            if (memberAccess != null)
            {
                if ((memberAccess.Member.MemberType == MemberTypes.Property) ||
                    (memberAccess.Member.MemberType == MemberTypes.Field))
                    return memberAccess.Member;
            }
            
            MethodCallExpression methodCall = propSelector.Body as MethodCallExpression;
            if (methodCall != null)
                return methodCall.Method;

            throw new ArgumentException("Можно тока филды и проперти и не void функции");
        }

        public static MemberInfo M<T>(this T myObj, Expression<Action<T>> propSelector)
        {
            if (propSelector.Body.NodeType != ExpressionType.Call)
                throw new ArgumentException("Это не селектор члена класса");

            MethodCallExpression methodCall = propSelector.Body as MethodCallExpression;
            if (methodCall != null)
                return methodCall.Method;

            throw new ArgumentException("Можно тока void функции");
        }
    }

    [MyTest1(Name="Name1", Description="Desc1")]
    public class MyTestClass
    {
        [MyTest2(Value1 = 7, Value2 = new double[] { 7, 8, 9 })]
        public string MyProp1 { get; set; }

        [MyTest2(Value1 = 3, Value2 = new double[] { 11, 18, 19 })]
        public void HelloWorld1() { }

        [MyTest2(Value1 = 31, Value2 = new double[] { 111, 181, 191 })]
        public int HelloWorld2(string msg) { return msg.Length; }
    }

    [AttributeUsage(AttributeTargets.Class)]
    public class MyTest1Attribute : Attribute
    {
        public string Name { get; set; }
        public string Description { get; set; }

        public MyTest1Attribute()
        {
        }
    }

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Property | AttributeTargets.Method)]
    public class MyTest2Attribute : Attribute
    {
        public int Value1 { get; set; }
        public double[] Value2 { get; set; }

        public MyTest2Attribute()
        {
        }
    }
}