C# Difference between factory pattern and IoC

Question

Possible Duplicate:
Dependency Injection vs Factory Pattern

Can someone please explain (with SIMPLE examples) of the difference between the factory pattern and Inversion of Control pattern. Preferably using .NET2.0

Do you mean "factory pattern" or "abstract factory pattern"? (The latter being closer in meaning to IoC.) — Enigmativity, Jan 24 '11 at 12:05
Duplicate: http://stackoverflow.com/questions/557742/dependency-injection-vs-factory-pattern — Mark Seemann, Jan 24 '11 at 12:20
@Mark The question may well be a duplicate but unfortunately it has no accepted answer. — Tim Lloyd, Jan 24 '11 at 12:22
@chibacity: Then the Q should explain why it is different clearly as an edit in your post. Also the levels of upvotes are such that the answers in the other thread are viable. Whether or not the asker has bothered to accept and/or follow up by explainign the missingn characteristics in the existing answers that would lead to an accept is not relevant. And if people feel it is, stick a bounty on it. Bottom line, it's a very similar question, so seconding VTC — Ruben Bartelink, Jan 24 '11 at 13:02
@Ruben I haven't asked a question. Using an unanswered questions as a duplicate to close this question is not necessarily helpful. — Tim Lloyd, Jan 24 '11 at 13:04
@Ruben The other question is a CW, can that now even have an accepted answer? — Tim Lloyd, Jan 24 '11 at 13:10
@Ruben What if the user with the highest voted answer decides to delete it? You can delete an answer if it hasn't been accepted. Perhaps there are other issues too. — Tim Lloyd, Jan 24 '11 at 13:18
@chibacity: Very conscious you're not the OP and just being a devil's advocate. Reiterate question: So what if it doesn't have an accepted answer when it has multipl good answers, all of which colour in the picture - this should be an appropriate result for someone asking the question as boradly as this question does. — Ruben Bartelink, Jan 24 '11 at 22:49
@Ruben Having had a think about it and asking a question on MSO, I agree. I think what's more important is that asking the same question multiple times fragments the question. It's better to close as a duplicate to direct back to a single source. Closing as a duplicate also brings attention back to the old question. I vote to close. — Tim Lloyd, Jan 24 '11 at 23:15

score 17 · Accepted Answer · edited Nov 09 '17 at 19:39

The factory pattern: the object which needs a reference to a service, should know about the factory that creates the Service:

public class BLLObject 
{
    public IDal DalInstance { get; set; }

    public BLLObject()
    {
        DalInstance = DalFactory.CreateSqlServerDal();
    }
}

The Ioc Pattern (or Dependency Injection) :

the object only needs to declare its need to the service, using any aspects of the Ioc Pattern (Constructor, setter, or interface ... etc) and the container will try to fulfill this need:

public class BLLObject 
{
    public IDal DalInstance { get; set; }

    public BLLObject(IDal _dalInstance)
    {
        DalInstance = _dalInstance;
    }
}

which means that in the factory pattern, the object decides which creation method (by choosing a specific concrete factory) to use, but the in the Ioc pattern, it is up to the container to choose.

of course this is not the only deference, but this is what is in my mind for the time being. correct me please if I'm wrong ?

score 1 · Answer 2 · answered Jan 24 '11 at 12:08

The factory pattern is about getting the reference to a type, so somewhere in your code you would be calling into a factory to resolve something.

The Inversion of control pattern means that you would typically use an Ioc container to resolve dependencies for you. This could be in a similar way to a factory, or more typically you would use dependency injection to resolve the dependencies into the constructor or setters.

C# Difference between factory pattern and IoC

2 Answers2