C#•2y ago

❔ Why hasn't my class implemented the interface?

public interface IFoo
{
    public IEnumerable<int> Get();
}

public class foo: IFoo
{
    public List<int> Get()
    {
        return null;
    }
}

public interface IFoo
{
    public IEnumerable<int> Get();
}

public class foo: IFoo
{
    public List<int> Get()
    {
        return null;
    }
}

Given that List<int> is a subtype of IEnumerable<int> I don't see what the issue is here.

10 Replies

333fred•2y ago

That's not how interface implementation works I mean, your link wasn't bad diddy There is a difference between overriding (that feature) and implementing (from an interface)

The Orange Tea FrogOP•2y ago

What does this mean

333fred•2y ago

Diddy posted a link, then deleted it

The Orange Tea FrogOP•2y ago

oh I see Basically my question is why isn't public List<int> Get() an implementation of public IEnumerable<int> Get(); when List is a subtype of IEnumerable

333fred•2y ago

Because that's not how implementations work It's the same type or nothing

The Orange Tea FrogOP•2y ago

Ok what is the reason for that

333fred•2y ago

To avoid unintentional implementation and ambiguities

The Orange Tea FrogOP•2y ago

Fair enough, I suppose I can still just return a List

333fred•2y ago

Correct

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Why hasn't my class implemented the interface?