Re: [boost] [move][unique_ptr] c++14 unique_ptr comes to town

El 26/08/2014 18:54, Peter Dimov wrote:

Mine is "more complete" in that it supports unique_ptr 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, 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 -> unique_ptr 2) unique_ptr -> unique_ptr 3) unique_ptr -> unique_ptr if remove_cv_t == remove_cv_t, 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 is be convertible to deleter 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 -> unique_ptr 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