c# Why can't open generic types be passed as parameters?
- by Rich Oliver
Why can't open generic types be passed as parameters. I frequently have classes like:
public class Example<T> where T: BaseClass
{
public int a {get; set;}
public List<T> mylist {get; set;}
}
Lets say BaseClass is as follows;
public BaseClass
{
public int num;
}
I then want a method of say:
public int MyArbitarySumMethod(Example example)//This won't compile Example not closed
{
int sum = 0;
foreach(BaseClass i in example.myList)//myList being infered as an IEnumerable
sum += i.num;
sum = sum * example.a;
return sum;
}
I then have to write an interface just to pass this one class as a parameter as follows:
public interface IExample
{
public int a {get; set;}
public IEnumerable<BaseClass> myIEnum {get;}
}
The generic class then has to be modified to:
public class Example<T>: IExample where T: BaseClass
{
public int a {get; set;}
public List<T> mylist {get; set;}
public IEnumerable<BaseClass> myIEnum {get {return myList;} }
}
That's a lot of ceremony for what I would have thought the compiler could infer. Even if something can't be changed I find it psychologically very helpful if I know the reasons / justifications for the absence of Syntax short cuts.
