c++ - 使用 boost void 分配器是不好的做法吗？

Question

我有时看到人们使用这样定义的通用空分配器:

using namespace boost::interprocess;
typedef allocator<void, managed_shared_memory::segment_manager> VoidAllocator;

这被认为是一种不好的做法吗？我发现 std::allocator 已贬值，我应该担心 boost 版本吗？

Answer 1

是的，原因是std::allocator<void>现在不受欢迎的也适用于其他声称是“虚空分配者”的事物。

根据p0174r0

Similarly, std::allocator<void> is defined so that various template rebinding tricks could work in the original C++98 library, but it is not an actual allocator, as it lacks both allocate and deallocate member functions, which cannot be synthesized by default from allocator_traits. That need went away with C++11 and the void_pointer and const_void_pointer type aliases in allocator_traits. However, we continue to specify it in order to avoid breaking old code that has not yet been upgraded to support generic allocators, per C++11.

您可以轻松定义模板别名。

using namespace boost::interprocess;
template <typename T>
using segment_allocator = allocator<T, managed_shared_memory::segment_manager>;