Extension methods in a class library project

Question

I implemented some extension methods and put them in a separate class library project.

Imagine I have a simple extension method like this in the MD.Utility class library :

namespace MD.Utility
{
    public static class ExtenMethods
    {
        public static bool IsValidEmailAddress(this string s)
        {
            Regex regex = new Regex(@"^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$");
            return regex.IsMatch(s);
        }
    } 
}

But nowhere in WebApp, for example, in the App_code folder or WebFroms code page, I can not use this extension method. If I like it:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MD.Utility;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string email = "[e-mail]";
        if (email.IsValidEmailAddress())
        {
            //To do 
        }
    }
}

The compiler does not recognize IsValidEmailAddress () and does not even support intellisense.

Although if I put my extension method in the App_Code folder, then it’s normal for use in another cs file in the App_code Folder folders or in a web form.

Answer 1

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Answer 6

In addition to adding the assembly to the links, it was fixed for me to explicitly add it to the file using MD.Utility.