ForAnyElementType

Development Programming & Scripting C++
, , ,
1 
template<typename T>
class TNoGrowAllocator : public T
{
public:
	class ForAnyElementType : public T::ForAnyElementType
	{
	public:
		FORCEINLINE typename T::SizeType CalculateSlackGrow(typename T::SizeType NumElements, typename T::SizeType NumAllocatedElements, SIZE_T NumBytesPerElement) const
		{
			ensure(false);
			return T::ForAnyElementType::CalculateSlackGrow(NumElements, NumAllocatedElements, NumBytesPerElement);

		}
	};

	template<typename ElementType>
	class ForElementType : public T::template ForAnyElementType<ElementType>
	{
	public:
		FORCEINLINE typename T::SizeType CalculateSlackGrow(typename T::SizeType NumElements, typename T::SizeType NumAllocatedElements, SIZE_T NumBytesPerElement) const
		{
			ensure(false);
			return T::template ForAnyElementType<ElementType>::CalculateSlackGrow(NumElements, NumAllocatedElements, NumBytesPerElement);
		}
	};
};

template<typename T, typename TAllocator = FDefaultAllocator>
using TNoGrowArray = TArray<T, TNoGrowAllocator<TAllocator>>;

template<typename T, typename TAllocator = FDefaultAllocator64>
using TNoGrowArray64 = TArray<T, TNoGrowAllocator<TAllocator>>;

template<typename T, typename TAllocator>
TArray<T, TAllocator>& FromNoGrowArray(TNoGrowArray<T, TAllocator>& Array)
{
	return reinterpret_cast<TArray<T, TAllocator>&>(Array);
}
template<typename T, typename TAllocator>
const TArray<T, TAllocator>& FromNoGrowArray(const TNoGrowArray<T, TAllocator>& Array)
{
	return reinterpret_cast<const TArray<T, TAllocator>&>(Array);
}

template<typename T, typename TAllocator>
TNoGrowArray<T, TAllocator>& ToNoGrowArray(TArray<T, TAllocator>& Array)
{
	return reinterpret_cast<TNoGrowArray<T, TAllocator>&>(Array);
}
template<typename T, typename TAllocator>
const TNoGrowArray<T, TAllocator>& ToNoGrowArray(const TArray<T, TAllocator>& Array)
{
	return reinterpret_cast<const TNoGrowArray<T, TAllocator>&>(Array);
}

this code doesnt compile in Unreal Engine 5, but Unreal Engine 4. It gives me the error: " [C2903]‘ForAnyElementType’: symbol is neither a class template nor a function template".

Can someone help?

2

The line

should probably instead be
class ForElementType : public T::template ForElementType<ElementType>.

And then

becomes
return T::template ForElementType<ElementType>::CalculateSlackGrow(NumElements, NumAllocatedElements, NumBytesPerElement);.

Assuming those are the lines where the compiler reports the error. Maybe the template wasn’t ever instanciated in UE4 and therefore never triggered the error?