Collection Bindings

Collection bindings make use of the BindMany<T>() or BindDictionary<T>() methods within a module. They involve creating one-to-many bindings.

List / Set Bindings

List and set bindings make use of the BindMany<T>() method within a module. They allow you to bundle implementations of a service together.

BindMany<List<ICommand>>()
    .To<InitializeCommand>()
    .To<PauseCommand>()
    .To<StartCommand>()
    .In(BindingScope.Singleton);

public sealed class ServiceImpl {
    private List<ICommand> commands;

    [Inject]
    public ServiceImpl(List<ICommand> commands) {
        this.commands = commands;
    }
    ...
}

Dictionary Bindings

Dictionary bindings make use of the BindDictionary<T>() method within a module. They allow you to map implementations of a service to keys.

BindDictionary<Dictionary<string, ICommand>>()
    .To("StartCommand", typeof(StartCommand))
    .To("StopCommand", typeof(StopCommand))
    .In(BindingScope.Singleton);

public sealed class ServiceImpl {
    private Dictionary<string, ICommand> commands;

    [Inject]
    public ServiceImpl(Dictionary<string, ICommand> commands) {
        this.commands = commands.
    }
    ...
}

Using with Untargeted Bindings

Untargeted Bindings can be used in conjunction with collection bindings to determine how the individual implementing types are instantiated.

In the above example, the List<ICommand> is bound as a singleton, so the entire list of values is cached after it is created. If you decided to inject a single command into another class, it would default to being instance-scoped.

BindMany<List<ICommand>>()
    .To<InitializeCommand>()
    .To<PauseCommand>()
    .To<StartCommand>()
    .In(BindingScope.Singleton);
Bind<PauseCommand>()
    .In(BindingScope.Singleton);

The PauseCommand will now share its instance with the List<ICommand> binding, regardless of the order in which they are requested.

Limitations

The type provided when calling BindMany<T>() must inherit from IEnumerable AND have an Add(value) method.

You must use the same type specified in the original Bind...<T>() call in order to have values injected.