Am I missing something or is this a Service Locator
anti-pattern? More about it here:
http://blog.ploeh.dk/2010/02/03/ServiceLocatorisanAnti-Pattern/
Service Locator is *really* an anti-pattern, but endovena (and
also dejector) is a Dependency Injector (DI) framework, opposite
of Service locator
(http://www.infoq.com/articles/Succeeding-Dependency-Injection)
DI is the solution to the principle of Inversion of Control
(IoC), and DI Framework is a Framework (!) that help you to
implement DI.
So, using Mark Seemann example:
```C#
public class OrderProcessor : IOrderProcessor
{
public void Process(Order order)
{
var validator = Locator.Resolve<IOrderValidator>();
if (validator.Validate(order))
{
var shipper = Locator.Resolve<IOrderShipper>();
shipper.Ship(order);
}
}
}
```
Using DI you should write:
```D
class OrderProcessor : IOrderProcessor {
private IOrderValidator validator;
this(IOrderValidator validator, IOrderShipper shipper) {
assert(validator !is null);
this.validator = validator;
this.shipper = shipper;
}
void Process(Order order) {
if (validator.Validate(order)) {
shipper.Ship(order);
}
}
}
```
in this version of OrderProcessor there is no Locator: the
dependencies (IOrderValidator and IOrderShipper) are passed
through constructor.
But... where is DI framework?
Endovena helps you to inject service into clients:
```D
import endovena;
void main() {
Container container = new Container;
container.register!(IOrderValidator,OrderValidator);
container.register!(IOrderShipper,OrderShipper);
container.register!(IOrderProcessor,OrderProcessor);
auto processor = container.get!IOrderProcessor();
processor.Process(order);
}
```
DI isn't easyto understand, but it's a very powerful pattern.
Some links:
*
http://www.theserverside.com/news/1321158/A-beginners-guide-to-Dependency-Injection
*
http://geekswithblogs.net/chrisfalter/archive/2008/02/15/new-statement-considered-harmful.aspx
*
http://comoyo.github.io/blog/2013/02/06/the-inverse-of-ioc-is-control/
*
http://www.loosecouplings.com/2011/01/dependency-injection-using-di-container.html
