Clonkex
Clonkex
PostsComments
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
you can't expect the compiler to allow you to return a list that has the possibility to contain FootBallEntity instances
Oh... yeah... that's super obvious. Idk why I didn't realise that immediately. Thanks
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
I guess I just assumed the compiler would treat T as being Entity since that's the constraint. But I also don't really know how generic methods are compiled. So using this as the example: 
T thing3 = (T)new BeachBallEntity();
T thing3 = (T)new BeachBallEntity();
...in my mind, T is known to be Entity, and BeachBallEntity is known to be Entity, so why am I not allowed to assign a reference to an instance of BeachBallEntity to a variable of type T? But then, you mention function calls for casting and I don't know why that would be necessary either. It seems like the cast to T could be entirely compiletime. Casting doesn't actually change the data (I assume?), it just changes what you're allowed to do with it. It seems the compiler wouldn't have to actually do anything. On the other hand there are obviously there are some casts that have to be runtime ((T)(object)new BeachBallEntity();, for instance). Hmm. This is quite unintuitive to me. Ultimately it's not important, I just wanted to understand why I wasn't allowed to return List<Entity> in a method with a return type of List<T> where T : Entity because it surprised me. Thanks for trying to explain it seems to be glancing off my smooth brain lol
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
ah true
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
Ha, I already changed it to add an empty list to the dictionary if it doesn't exist rather than allocating a new one each time. I just didn't edit the original post
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
So I didn't realise this (assume BeachBallEntity : Entity): 
T thing = (T)new Entity();           // Allowed
Entity thing2 = new T();             // Allowed
T thing3 = (T)new BeachBallEntity(); // Not allowed?
T thing = (T)new Entity();           // Allowed
Entity thing2 = new T();             // Allowed
T thing3 = (T)new BeachBallEntity(); // Not allowed?
I'm not really sure why this is. Even if T is MoreSpecificBeachBallEntity, it's generic, so it's not like I can try to call methods that would only exist for MoreSpecificBeachBallEntity, for instance. T is only known to be Entity so it should be safe to cast any subclass of Entity to T, should it not?
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
No it's not intended to be modifed from outside. I was planning to use IEnumerable or IReadOnlyList, I just didn't get that far.
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
Edited. I really did not include enough information lol
55 replies
CC#
Created by Clonkex on 9/5/2023 in #help
✅ Return List<Entity> from method with return type of List<T> where T : Entity
Ah yes, sorry. Or more specifically, List<SomeTypeDerivedFromEntity>
55 replies