How can I extend my class from a nested in another generic class?

Question

I'm new to C# (I am a Java developer) and have a question about generics. I have a generic class with nested classes:

public class FlowChartBuilder<TEntity, TLink> 
    where TEntity : FlowChartBuilder<TEntity, TLink>.Entity
    where TLink : FlowChartBuilder<TEntity, TLink>.Link
{
    public abstract class Link { }
    public abstract class Entity { }
}

The next I try to extends these classes:

public class ChartEntity<T>: FlowChartBuilder<ChartEntity<T>, ChartLink>.Entity
{
}

public class ChartEntity<T>: FlowChartBuilder<ChartEntity<T>, ChartLink<ChartEntity<T>>>.Entity
{
}

But I get an error:

"TEntity" type can't be used like a parameter of "TEntity" type in the universal type or method "FlowChartBuilder". There isn't a transformation-packaging or a transformation of a type parameter from the "TEntity" to the "PM.Utils.Diagram.FlowChartBuilder>.Entity".

How to write it correct?

I think this a duplicate of this http://stackoverflow.com/questions/21566701/nested-class-that-inherits-from-its-generic-parent-class may be you will find your answer in it. It tells to replace inheritance with encaspulation. — Bruno Belmondo, Jan 19 '17 at 13:18
Why nest the classes if you're just going to make them public? http://stackoverflow.com/a/7984625/302918 — juharr, Jan 19 '17 at 13:19
@juharr, I need it to hide a realization of some parts of classes but to it still was available in my generic class. I just removed class bodies. — Denis Sologub, Jan 19 '17 at 13:22

score 2 · Answer 1 · edited May 23 '17 at 11:45

2

What you are trying to do is impossible. Use Composition over inheritance instead.

Check here for a workaround Nested class that inherits from its generic parent class

edited May 23 '17 at 11:45

Community

1
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answered Jan 19 '17 at 13:21

Bruno Belmondo

2,299
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Sorry, I got a jerk on. It doesn't suit in my case. Or I bad got it. – Denis Sologub Jan 19 '17 at 13:29
Could you provide the use case? You won't be able to inherit those class so please tell us why you wanted to do this in the first place. – Bruno Belmondo Jan 19 '17 at 13:31
To I could have an access to private members of these nested classes. Maybe, C# has some another way, just I don't know. – Denis Sologub Jan 19 '17 at 13:32
1

private member are "private". There is no way to access any data inside it. – Bruno Belmondo Jan 19 '17 at 13:34
Waah, guy, sorry) You're right, of course. Inner class has access to an outer (in Java, I didn't check it in C#). I need a rest already – Denis Sologub Jan 19 '17 at 13:37
But if I already wrote this. I still want to understand how to build so class hierarchy or equals. – Denis Sologub Jan 19 '17 at 13:39

How can I extend my class from a nested in another generic class?

1 Answers1