Right now I'm trying to teach myself the Dependency Injection pattern with the IOC-container from Autofac. I've come up with a very simple example, which is presented below. Although the example is simple, I fail to get it working properly.
Here are my classes/interfaces:
Two monsters, both implementing the IMonster interface:
interface IMonster
{
void IntroduceYourself();
}
class Vampire : IMonster
{
public delegate Vampire Factory(int age);
int mAge;
public Vampire(int age)
{
mAge = age;
}
public void IntroduceYourself()
{
Console.WriteLine("Hi, I'm a " + mAge + " years old vampire!");
}
}
class Zombie : IMonster
{
public delegate Zombie Factory(string name);
string mName;
public Zombie(string name)
{
mName = name;
}
public void IntroduceYourself()
{
Console.WriteLine("Hi, I'm " + mName + " the zombie!");
}
}
Then there's my graveyard:
interface ILocation
{
void PresentLocalCreeps();
}
class Graveyard : ILocation
{
Func<int, IMonster> mVampireFactory;
Func<string, IMonster> mZombieFactory;
public Graveyard(Func<int, IMonster> vampireFactory, Func<string, IMonster> zombieFactory)
{
mVampireFactory = vampireFactory;
mZombieFactory = zombieFactory;
}
public void PresentLocalCreeps()
{
var vampire = mVampireFactory.Invoke(300);
vampire.IntroduceYourself();
var zombie = mZombieFactory.Invoke("Rob");
zombie.IntroduceYourself();
}
}
And finally my main:
static void Main(string[] args)
{
// Setup Autofac
var builder = new ContainerBuilder();
builder.RegisterType<Graveyard>().As<ILocation>();
builder.RegisterType<Vampire>().As<IMonster>();
builder.RegisterType<Zombie>().As<IMonster>();
var container = builder.Build();
// It's midnight!
var location = container.Resolve<ILocation>();
location.PresentLocalCreeps();
// Waiting for dawn to break...
Console.ReadLine();
container.Dispose();
}
And this is my problem: During runtime, Autofac throws an exception on this line:
var vampire = mVampireFactory.Invoke(300);
It seems that the mVampireFactory is actually trying to instantiate a zombie. Of course this won't work since the zombie's constructor won't take an int.
Is there a simple way to fix this? Or did I get the way Autofac works completely wrong? How would you solve this problem?
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