Re: When are data structures copied
On 07/11/09 02:04, tohava wrote:
On Nov 6, 1:21 am, ShaunJ<sjack...@gmail.com> wrote:
avoided? Do any implementations of STL implement copy-on-write
semantics for string or vector?
I'm not 100% sure, but I think STLPort implements string with CoW.
Current STLPort-5.2.1 and STLPort 4 bundled with the latest Sun C++
compilers do not not use CoW. One most disappointing feature of STLPort
std::string is that the default constructor allocates storage, in other
words, a memory allocation is performed even for empty strings.
GNU std::string uses CoW. I hear that the standard interface of
std::string can not be possibly satisfied by a CoW implementation of
std::string, nevertheless I find CoW implementations of std::string the
most practical.
GNU C++ library also provides another string class
__gnu_cxx::__versa_string, which does not do CoW and I've heard that
there are plans to make it the default std::string implementation in the
future, although the CoW std::string implementation will still be
available under a different name.
--
Max
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]