_Alloc_hider?

[Jonathan Wakely]

On 16 August 2011 00:43, Jonathan Wakely wrote:
> On 16 August 2011 00:30, Jeffrey Walton wrote:
>> Hi All,
>>
>> I'm testing a custom allocator. The allocator works well with vector,
>> but fails to link with basic_string (see below).
>>
>> I looked through Stroustrup and could not find info on _Alloc_hider.
>
> It starts with an underscore followed by an upper case letter, so it's
> in the implementation namespace i.e. it's an implementation detail, so
> you're not going to find it in a book.
>
>
>> Searching online doesn't reveal much either (perhaps I have not waded
>> through enough irrelevant fodder). I did find [1], buts its just
>> DoOxygen with no real content (its written in STL terseness with no
>> comments).
>>
>> I believe I need another constructor, but I'm not sure what it takes
>> or how to write it:
>>
>>  inline explicit zallocator() { }
>>  inline ~zallocator() { }
>>  inline explicit zallocator(zallocator const&) { }
>>
>>  template<typename U>
>>  inline explicit zallocator(zallocator<U> const&) { }
>>
>> How does one one provided an allocator for use by a basic_string?
>
> By writing a type that meets the C++03 Allocator requirements, which
> yours doesn't.

Hmm, I might have been too hasty - that constructor might be allowed
to be 'explicit' which would make it a bug that we don't support
allocators like yours - I'll have to investigate tomorrow.

Removing 'explicit' should still fix the problem anyway.