"java wildcard" to C#?

Question

How do I convert this "java wildcards" to C# format?

public abstract class AAA<T extends BBB<?>> extends CCC<T>{}

My incorrect C# code

public abstract class AAA<T> : CCC<T> where T : BBB<?>{}

How do I convert BBB<?>

You could have class BBB implement a non-generic interface "YYY" and then just use "where T : YYY". — Dave Doknjas, May 12 '15 at 01:10

score 1 · Answer 1 · edited May 23 '17 at 11:45

There is a similar question C# generic "where constraint" with "any generic type" definition? not specific to Java wildcards. The answer provided there will likely help you.

From that answer, a possible class signature would be:

public abstract class AAA<T, TOther> : CCC<T>
    where T : BBB<TOther>
{}

Generics in C# must have named type parameters even if you never plan to use the type explicitly/implicitly. And all type parameters must be named in the identifier declaration of the method/class/interface.

Note that it would be possible to constrain TOther to just object types if so desired using:

public abstract class AAA<T, TOther> : CCC<T>
    where T : BBB<TOther>
    where TOther : object
{}

score 0 · Answer 2 · answered May 12 '15 at 02:25

0

What is BBB exactly?

I bet that BBB<Object> probably would work; BBB is likely a covariant type.

answered May 12 '15 at 02:25

ZhongYu

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BBB – Arkaine55 May 12 '15 at 02:48
@Arkaine55 but OP is talking about C#. I suspect that here `BBB` is a covariant type, which in C#, `BBB` *is-a* `BBB – ZhongYu May 12 '15 at 02:53
@bayou-io My comment is only using C#. C# 4 the variance rules with generics require more explicit definitions. http://stackoverflow.com/questions/2033912/c-sharp-variance-problem-assigning-listderived-as-listbase So if BBB is defined as `class BBB` your answer would probably be fine. I still don't like assuming what BBB is. – Arkaine55 May 12 '15 at 03:30

"java wildcard" to C#?

2 Answers2