How to avoid Dependency Injection constructor madness?

JP Richardson picture JP Richardson · Mar 10, 2010 · Viewed 71.2k times · Source

I find that my constructors are starting to look like this:

public MyClass(Container con, SomeClass1 obj1, SomeClass2, obj2.... )

with ever increasing parameter list. Since "Container" is my dependency injection container, why can't I just do this:

public MyClass(Container con)

for every class? What are the downsides? If I do this, it feels like I'm using a glorified static. Please share your thoughts on IoC and Dependency Injection madness.

Answer

Mark Seemann picture Mark Seemann · Mar 10, 2010

You are right that if you use the container as a Service Locator, it's more or less a glorified static factory. For lots of reasons I consider this an anti-pattern.

One of the wonderful benefits of Constructor Injection is that it makes violations of the Single Responsibility Principle glaringly obvious.

When that happens, it's time to refactor to Facade Services. In short, create a new, more coarse-grained interface that hides the interaction between some or all of the fine-grained dependencies you currently require.