Custom scope for Ninject that returns same instance based on first constructor argument. Using both kernel and factory

gistfile1.cs

void Main()
{
    using(var kernel = new StandardKernel(new Module()))
    {
        kernel.Load<FuncModule>(); // for sake of LinqPAD
    
        var instance1 = kernel.Get<MyClass>(new ConstructorArgument("myArg", "test"));
        var instance2 = kernel.Get<MyClass>(new ConstructorArgument("myArg", "test"));
        
        Assert.That(instance1, Is.Not.Null.And.SameAs(instance2));
        
        var instance3 = kernel.Get<MyClass>(new ConstructorArgument("myArg", "rest"));
        
        Assert.That(instance3, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance3, Is.Not.Null.And.Not.SameAs(instance2).And.Not.EqualTo(instance2));
        
        var instance4 = kernel.Get<MyClass>(new ConstructorArgument("myArg", "best"));
        
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance3).And.Not.EqualTo(instance3));
        
        var factory = kernel.Get<IMyClassFactory>();
        
        instance1 = factory.Create("test");
        instance2 = factory.Create("test");
        
        Assert.That(instance1, Is.Not.Null.And.SameAs(instance2));
        
        instance3 = factory.Create("rest");
        
        Assert.That(instance3, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance3, Is.Not.Null.And.Not.SameAs(instance2).And.Not.EqualTo(instance2));
        
        instance4 = factory.Create("best");
        
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance1).And.Not.EqualTo(instance1));
        Assert.That(instance4, Is.Not.Null.And.Not.SameAs(instance3).And.Not.EqualTo(instance3));
    }
}
 
public class MyClass
{
    public string MyArg { get; private set; }
    
    public MyClass(string myArg)
    {
        MyArg = myArg;
    }
    
    public override bool Equals(object other)
    {
        if(other == null
            || other.GetType() != typeof(MyClass))
        {
            return false;
        }
        
        return MyArg == ((MyClass)other).MyArg;
    }
    
    public override int GetHashCode()
    {
        return (MyArg ?? string.Empty).GetHashCode();
    }
}
 
public interface IMyClassFactory
{
   MyClass Create(string myArg);
}
 
public class Module : NinjectModule
{
    // stores string myArg to protect from CG
    ConcurrentBag<string> ParamSet = new ConcurrentBag<string>();
 
    public override void Load()
    {
        Bind<IMyClassFactory>()
            .ToFactory();
    
        Bind<MyClass>()
            .ToSelf()
            // custom scope
            .InScope((context) =>
                {
                    // get first constructor argument
                    var param = context.Parameters.First().GetValue(context, context.Request.Target) as string;                    
                    
                    // retrieves system reference to string
                    param = string.Intern(param);
                    
                    // protect value from CG
                    if(param != null && ParamSet.Contains(param))
                    {
                        // protect from GC
                        ParamSet.Add(param);
                    }
                    
                    // make Ninject to return same instance for this argument
                    return param;
                });
    }
}