John Maddock" wrote:
basic_string and other containers take an allocator template argument, while basic_regex does not.
If basic_regex had an allocator it would reap all the same benefits that other string and container types do. In particular, it would be possible to use boost::interprocess to place them in shared memory.
IIUC, 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. Is this level of functionality useful to you?
That would certainly be a killer blow as far as using this with regex is concerned... but don't you have the option of at least trying to load shared memory at a specific address?
Yes you can ask to map it at a particular address, but that can fail. Actually there is another case that I forgot about before: if you create the shared memory before forking, the new process will see it at the same address as its parent. So this could be useful in that situation. Sorry, it's a while since I did anything with shared memory... Phil.