How to implement both generic and non-generic version of a class?

Question

I want to implement a non-generic version of my generic class. Like this.

public class ServerSentEvent : ServerSentEvent<NoAdditionalClientInformation>

public class ServerSentEvent<ClientInfo> : IServerSentEvent

To solve this I had to make a dummy/empty class - NoAdditionalClientInformation.

Is there another way to do this without the empty class?

do you know the type when you say non generic of generic? if yes then just use it.. — D J
– D J, Commented Jan 16, 2013 at 7:17
If you look at .NET BCL classes you will notice that the generic versions are child classes of the non generic versions and not the other way round. For example IEnumerable<T> implements IEnumerable. — Darin Dimitrov
– Darin Dimitrov, Commented Jan 16, 2013 at 7:18
What if the generic class inherited from the non-generic one: public class ServerSentEvent<TClientInfo> : ServerSentEvent and public class ServerSentEvent : IServerSentEvent? — Mike Zboray
– Mike Zboray, Commented Jan 16, 2013 at 7:19
@DarinDimitrov can you give an example of generic class that a child of non-generic? — Sergey Berezovskiy
– Sergey Berezovskiy, Commented Jan 16, 2013 at 7:21
@lazyberezovsky ChannelFactory<TChannel> inherits from ChannelFactory — Mike Zboray
– Mike Zboray, Commented Jan 16, 2013 at 7:23

poke · Accepted Answer · 2013-01-16 07:24:26Z

19

Usually you’d just do it the other way around:

public class ServerSentEvent : IServerSentEvent
{}

public class ServerSentEvent<ClientInfo> : ServerSentEvent
{}

That way the generic version is a more specified subtype of the non-generic one allowing you to put more information in it but to use the generic type whereever a non-generic type is expected.

If you do it like you suggested, you would need to have to specify some default type; if you can’t think of a default one, it is probably the wrong order, but in general it might depend on the case.

answered Jan 16, 2013 at 7:24

poke

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5 Comments

Ferit Over a year ago

Could you provide a more detailed example?

poke Over a year ago

@Saibot For what exactly? Maybe you should ask your own question?

Ferit Over a year ago

Yeah, then it would be marked as duplicate in 10 seconds :D

Ferit Over a year ago

I would like to see a case where we can benefit implementing both generic and non generic versions. I am having trouble to understand why this is necessary (or is it necessary at all?) and how to use this pattern properly.

poke Over a year ago

@Saibot As an example, see IEnumerable<T> and IEnumerable. IEnumerable<T> inherits from IEnumerable, so every generic enumerable is also a non-generic enumerable. The benefit of this is that anything that works with any enumerable will also work for generic enumerables. Another example would be Task<T> and Task.

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