On Fri, Nov 16, 2012 at 8:50 PM, Yanchenko Maxim <maximyanchenko@yandex.ru>wrote:
On Fri, Nov 16, 2012 at 7:18 PM, Yanchenko Maxim <maximyanchenko@yandex.ru>wrote:
I do not see it as an optimization tool. As written in the first
17.11.2012, 02:29, "Yakov Galka" <ybungalobill@gmail.com>: paragraph
of the paper it is intended to remove such nonsense in the future:
void open(const char *p, ios_base::openmode = ...); void open(const std::string &p, ios_base::openmode = ...); // added in C++11
runtime_error(const char *p); runtime_error(const std::string &p); // added in C++11
First, it wasn't a big deal to write c_str() while sending an std::string to open().
I agree. I would leave it a const char *. Second, instead of adding an overload, they could just replace it with
std::string version - everything would work as expected (except code that uses exact signatures).
I guess you cannot use exact signatures of member functions (the implementation is permitted to add arbitrary default parameters). This will, however, break existing code. When you call f.open("xyz") no std::string is constructed in C++03, so no operator new is called. Changing it to const std::string & would change this behavior. Or you care about unnecessary std::string creation? Then it's optimization.
(I believe you don't really care about it in face of file operations.)
I do not care for the file case, but for other things that accept strings it may matter (like runtime_error -- it adds one more heap allocation. This is important in error handling, where you do not want to increase the likelihood of failing to create an exception object). [...] If you care not about speed but about clean and *generic* interface
(just std::string is already clean enough), then you need a templated open(iterator_range, openmode) where iterator_range can be any char sequence (e.g. coming from expression-template code like dir+'/'+filename+'.'+ext).
I care for as generic code as possible within the limits of separate compilation.
[...]
This discussion has already been raised here in the context of boost program_options.
Could you give me a reference subj or a link, please?
http://boost.2283326.n4.nabble.com/program-options-Some-methods-take-const-c... -- Yakov