Pattern: NullObject

Description

Instead of returning null,use an object which implements the expected interface,but whose method body is empty.

Examples in .NET :

EmptyFolder

using System;
using System.IO;

namespace NullObject;
internal class EmptyFolderDemo
{
    public static void DemoWithCreateNewFolder()
    {
        //start example 1
        var env = Environment.CurrentDirectory;
        var guid = Guid.NewGuid().ToString("X");
        var fldEmpty = Path.Combine(env,guid);
        //create empty folder
        Directory.CreateDirectory(fldEmpty);
        var files= Directory.GetFiles(fldEmpty);
        Console.WriteLine($"files.Length:{files.Length}");
        //end example 1
        
    }
}

NullLogger

namespace NullObject;
internal class LogWithData
{
    ILogger _logger;
    public LogWithData(ILogger? logger=null)
    {
        _logger = logger ?? NullLogger.Instance;   
    }
    public void DoWork(string message)
    {
        _logger.LogInformation($"start work with {message}");
    }
}

Learn More

Wikipedia

Homework

When retrieving data( e.g. a Person with ID =-1 ) from a database,return a NullObject instead of null. How you will verify that the object is a NullObject?