Dependency Injection – new instance required in several of a classes methods

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Most of the answers here so far suggest that you change the injected dependency type to some sort of Abstract Factory (a Func<T> is also an Abstract Factory) to address the issue. However, if you do that it would be a leaky abstraction because you would let the knowledge of a particular implementation determine the design of the consumer. This violates the Liskov Substitution Principle.

A better option is to keep MyService as it is, and then create a wrapper for IDependency that addresses the particular lifetime issue:

public class TransientDependencyWrapper : IDependency
{
    public void DoSomething()
    {
        new MyStatefulDependency().DoSomething();
    }
}

Inject that into MyService instead of directly injecting the original implementation (MyStatefulDependency).

If you want to abstract away the creation of the dependency, you can always inject an Abstract Factory at this level.

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