El 26/08/2014 18:54, Peter Dimov wrote:
Mine is "more complete" in that it supports unique_ptr<T[N]> with proper shared_ptr-style conversions and is "better" in that it does all that with a single template, without triplication.
Hi Peter, I've committed changeds to boost::movelib::unique_ptr now supports unique_ptr<T[N]>, adding the operator[] check mentioned in shared_ptr documentation. I have some doubts with these conversions. Currently I've implemented the conversions: 1) unique_ptr<T[]> -> unique_ptr<U[]> 2) unique_ptr<T[N]> -> unique_ptr<U[N]> 3) unique_ptr<T[N]> -> unique_ptr<U[]> if remove_cv_t<T[]> == remove_cv_t<U[]>, pointers are convertible and deleters are convertible (and this is the key point). Although not provided by the language (T(*)[N] is not convertible to U(*)[]), the third conversion is safe with the default deleter. A problem might occure if a user-provided deleter<T[N]> is be convertible to deleter<U[]> but it does not properly handle unknown-length arrays. The conversion will be unsafe. Deleter writers should be warned about this conversion. On the other hand, with the default_deleter it could be safe to convert (maybe if N >= M): 4) unique_ptr<T[N]> -> unique_ptr<U[M]> that is, we can safely create a slice of the array. I don't know if this conversion has any value. I understand conversion 3 is useful to get some data erasure and avoid propagating size though all the code. Is interesting to allow such conversion? Best, Ion