CODEWITHSUNDEEP
c#dependency-injectionninject
Ryan
Ryan

Reputation: 24482

How could this be rewritten using ninject?

What would the following example look like re-written to use Ninject?

Specifically how would you bind a Samurai to both Shuriken and Sword?

(From https://github.com/ninject/ninject/wiki/Dependency-Injection-By-Hand)

interface IWeapon
{
    void Hit(string target);
}

class Sword : IWeapon
{
    public void Hit(string target) 
    {
        Console.WriteLine("Chopped {0} clean in half", target);
    }
}

class Shuriken : IWeapon
{
    public void Hit(string target)
    {
        Console.WriteLine("Pierced {0}'s armor", target);
    }
}

class Program
{
    public static void Main() 
    {
        var warrior1 = new Samurai(new Shuriken());
        var warrior2 = new Samurai(new Sword());
        warrior1.Attack("the evildoers");
        warrior2.Attack("the evildoers");    
       /* Output...
        * Piereced the evildoers armor.
        * Chopped the evildoers clean in half.
        */
    }
}

Upvotes: 0

Views: 137

Answers (1)

Nikola Anusev
Nikola Anusev

Reputation: 7088

You could simply rebind IWeapon after resolving first Samurai:

StandardKernel kernel = new StandardKernel();

kernel.Bind<IWeapon>().To<Sword>().Named();
Samurai samurai1 = kernel.Get<Samurai>();
samurai1.Attack("enemy");

kernel.Rebind<IWeapon>().To<Shuriken>();
Samurai samurai2 = kernel.Get<Samurai>();
samurai2.Attack("enemy");

Alternatively, you could use named bindings. It would be first necessary to redefine Samurai's constructor a bit, adding a Named attribute to its dependency:

public Samurai([Named("Melee")]IWeapon weapon)
{
    this.weapon = weapon;
}

Then, you would need to give names to your bindings as well:

StandardKernel kernel = new StandardKernel();

kernel.Bind<IWeapon>().To<Sword>().Named("Melee");
kernel.Bind<IWeapon>().To<Shuriken>().Named("Throwable");

Samurai samurai = kernel.Get<Samurai>();
samurai.Attack("enemy"); // will use Sword

There are really many alternatives - I would recommend browsing over the link provided by @scottm and checking them all out.

Upvotes: 2

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