Factory Bindings

Factory bindings make use of the BindFactory<T>() method within a module.

They allow you to create implementations of a type with consumer-provided values.

public IConnectionFactory {
    IConnection Create(string url, int port);
}

public Connection : IConnection {
    private string url;
    private int port;
    private IConnectionConfiguration configuration;

    [Inject]
    private Connection(string url, int port, 
            IConnectionConfiguration configuration) {
        this.url = url;
        this.port = port;
        this.configuration = configuration;
    }
}
...
BindFactory<IConnectionFactory>()
    .Implement<IConnection, Connection>();
...

var factory = injector.Get<IConnectionFactory>();
var connection = factory.Create("/service", 8000);

In the above example, the fields url and port are passed from the factory to the new Connection instance. The configuration field is supplied by the injector.

Named Parameters

If you have multiple parameters of the same type, it is necessary to name them, otherwise injection is not possible.

public IPersonFactory {
    IPerson Create(
        [Name("firstname")] string firstname, 
        [Name("lastname")] string lastname,
        int age);
}

public Person : IPerson {
    private string firstname;
    private string lastname;
    private int age;

    [Inject]
    private Person(
            [Name("firstname")] string firstname, 
            [Name("lastname")] string lastname,
            int age) {
        this.firstname = firstname;
        this.lastname = lastname;
        this.age = age;
    }
}
...
BindFactory<IPersonFactory>()
    .Implement<IPerson, Person>();
...

var factory = injector.Get<IPersonFactory>();
var person = factory.Create("John", "Smith");

_{This example is really bad, but I was having trouble thinking of something to illustrate this.}