DeferredRegister with custom generic registry

[Alpvax]

DeferredRegister has been updated recently to make it work with custom registries, but it still doesn't work with custom generic RegistryObjects (similar to TileEntityType<T>).

 

When trying to create the DeferredRegister, it errors with: 

Quote

Required type: DeferredRegister<IOType<?>>
Provided: DeferredRegister<IOType>
Incompatible equality constraint: IOType<?> and IOType

//Registry
  public static final DeferredRegister<IOType<?>> IO_TYPES = DeferredRegister.create(IOType.class, MODID);

//IOType.java (currently just a stub)
public abstract class IOType<T> extends ForgeRegistryEntry<IOType<?>> {
}

 

Is there a workaround for this issue, or can I just not use DeferredRegister? This will be available in an API, so I would ideally be able to support the more popular DeferredRegister approach.

 

Removing the parametised type (DeferredRegister<IOType> IO_TYPES = ...) then throws the error of IOType not implementing IForgeRegistryEntry<IOType>, so that isn't a fix.

I am wondering if the only workaround is to make the registry in a static initialiser (and overriding it in the NewRegistryEvent), but that seems like a step backwards.

 

Does anyone have any suggestions?

[diesieben07]

A shortcoming of Java's generics, I think.

You probably need to use raw types and lots and lots of unchecked casts.

[Alpvax]

Worked around the issue by double unchecked casting the type:

public abstract class IOType<T> extends ForgeRegistryEntry<IOType<?>> {
    @SuppressWarnings("unchecked")
    public static final Class<IOType<?>> CLASS_GENERIC = (Class<IOType<?>>)((Class<?>)IOType.class);
}

//Can then be used as follows
public static final DeferredRegister<IOType<?>> IO_TYPES = DeferredRegister.create(IOType.CLASS_GENERIC, MODID);

By putting the constant in the API class, it can be used by others who are consuming the API.