Use generic type in class constructor

Question

I have an Interface and an Abstract class with its derived one:

  public interface IIndicator<TInput, TOutput> { } 

  public abstract class Indicator<TInput, TOutput> : IIndicator<TInput, TOutput> {

    public abstract TOutput Calculate(TInput input);

  }

  public class MyIndicator : Indicator<Decimal, Decimal?> {

    public MyIndicator(IEnumerable<Decimal> inputs) {
      // Code using base.Calculate and inputs
    }

    public MyIndicator(IEnumerable<Decimal> inputs, Func<TMapper, Decimal> mapper) {

      // Code using base.Calculate, inputs and mapper 

    } 

    public override TOutput Calculate(TInput input) {
      // Implementation of Calculate
    }

  }

The problem is that TMapper is not defined in the contructor:

public MyIndicator(IEnumerable<Decimal> inputs, Func<TMapper, Decimal> mapper, Int32 period)

I would like to use MyIndicator as:

MyIndicator indicator = new MyIndicator(inputs, x => x.Id)

Instead of:

MyIndicator<MyClass> indicator = new MyIndicator<MyClass>(inputs, x => x.Id)

Where MyClass would be something like:

public class MyClass { 
  public Int32 Id { get; set; }
}

Is this possible?

You simply need to specify MyClass instead of TMapper because there's nothing else it can be with the syntax you want. — madreflection
– madreflection, Commented Dec 10, 2019 at 19:36
It won't happen unless you specify a constructor argument that represent the object of the MyClass and should appear before the Mapper lambda. — vendettamit
– vendettamit, Commented Dec 10, 2019 at 19:59

Johnathan Barclay · Accepted Answer · 2019-12-10 21:58:23Z

5

Use a factory method instead e.g.

public static MyIndicator Create<TMapper>(IEnumerable<decimal> inputs, Func<TMapper, decimal> mapper, int period)
{
    var indicator = new Indicator(inputs);
    // do stuff with your mapper / period
    return indicator;
}

edited Dec 10, 2019 at 21:58

answered Dec 10, 2019 at 19:43

Johnathan Barclay

20.5k2 gold badges27 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Silvermind Over a year ago

Typo I guess, but I think you meant Create<TMapper>(...).

Collectives™ on Stack Overflow

Use generic type in class constructor

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related