c# - Base Class type for ILogger<T> using Dependency Injection

Question

I have a base class that does some work, including logging. I have an ILogger dependency injected into the constructor

public abstract class BaseClassExample
{
    protected readonly ILogger<BaseClassExample> logger;

    public class BaseClassExample(ILogger<BaseClassExample> logger)
    {
        this.logger = logger;
    }
}

And I want to have classes implement BaseClassExample, and do their own work too, also including logging.

public class DerivedClass : BaseClassExample
{
    protected readonly ILogger<DerivedClass> logger;

    public class BaseClassExample(ILogger<DerivedClass> logger)
    {
        this.logger = logger;
    }
}

Is this the right way of doing things? Am I supposed to get the implementing class's type for logging for the base class? Should I have a separate instance of a logger (with the DerivedClass's type) or try and use the same one as the base class?

Answer 1

use a none generic ILogger in your base class, but ILogger<DerivedClass> in your derived class. This way you can simply pass the ILogger to your base class if needed:

public abstract class BaseClassExample
{
    private readonly ILogger logger;

    public class BaseClassExample(ILogger logger)
    {
        this.logger = logger;
    }
}

and

public class DerivedClass : BaseClassExample
{
    private readonly ILogger<DerivedClass> logger;

    public class BaseClassExample(ILogger<DerivedClass> logger)
                  :base(logger)
    {
        this.logger = logger;
    }
}

this way not only you can use it easier if you somehow end up with two derived class you can use ILogger in both of them.