Re: [boost] Interprocess regexes

Subject: Re: [boost] Interprocess regexes
From: John Maddock (john_at_[hidden])
Date: 2009-12-06 04:55:38

>> while the custom allocators let you put std::containers in shared memory 
>> they are still not very useful since they can only be used by the process 
>> that put them there - other processes will (potentially) see the shared 
>> memory at a different address and all the pointers will be wrong
>
> Isn't this *exactly* what the allocator's nested ::pointer type is for?

Maybe, but it's use would be pretty limited.  The std lib is entitled to 
assume that:

"The typedef members pointer, const_pointer, size_type, and difference_type 
are
required to be T*,T const*, size_t, and ptrdiff_t, respectively"

So I wouldn't be able to use any std lib containers within regex if we were 
to allow the ::pointer type to be useful :-(

And boost::shared_ptr, while allocating it's memory via an allocator is 
completely agnostic about it's type, so I couldn't use any smart pointer 
classes either :-(

So... all I would need to do is reimplement the std lib, and shared_ptr 
etc... or maybe not!

Which is not to say that having an allocator for other purposes isn't 
worthwhile,

Cheers, John.