allocator

问题 Why isn't there an array template specialization for std::allocator<T[]> in c++14? When playing around trying to specialize std::allocator<T[]> myself I hit a dead-end when implementing the construct() and destroy() method. Is this the reason? Why then have construct() and destroy() part of std::allocator<>? template <T> class allocator <T[]> { // ...most is similar for std::allocator<>... template <class U, class... Args> void construct( U *p, Args&&.. args) { // what to write for array

问题 Why isn't there an array template specialization for std::allocator<T[]> in c++14? When playing around trying to specialize std::allocator<T[]> myself I hit a dead-end when implementing the construct() and destroy() method. Is this the reason? Why then have construct() and destroy() part of std::allocator<>? template <T> class allocator <T[]> { // ...most is similar for std::allocator<>... template <class U, class... Args> void construct( U *p, Args&&.. args) { // what to write for array

问题 Why isn't there an array template specialization for std::allocator<T[]> in c++14? When playing around trying to specialize std::allocator<T[]> myself I hit a dead-end when implementing the construct() and destroy() method. Is this the reason? Why then have construct() and destroy() part of std::allocator<>? template <T> class allocator <T[]> { // ...most is similar for std::allocator<>... template <class U, class... Args> void construct( U *p, Args&&.. args) { // what to write for array

问题 Why isn't there an array template specialization for std::allocator<T[]> in c++14? When playing around trying to specialize std::allocator<T[]> myself I hit a dead-end when implementing the construct() and destroy() method. Is this the reason? Why then have construct() and destroy() part of std::allocator<>? template <T> class allocator <T[]> { // ...most is similar for std::allocator<>... template <class U, class... Args> void construct( U *p, Args&&.. args) { // what to write for array

问题 I have a vector<vector<int>> and want the entire memory (i.e., of both the outer and the inner vector) to be taken from a memory_resource . Here is a stripped down example, first the boring part: #include <boost/container/pmr/memory_resource.hpp> #include <boost/container/scoped_allocator.hpp> #include <boost/container/pmr/polymorphic_allocator.hpp> #include <iostream> #include <string> #include <vector> // Sample memory resource that prints debug information class MemoryResource : public

来源： https://stackoverflow.com/questions/37502974/stdstring-with-a-custom-allocator

来源： https://stackoverflow.com/questions/37502974/stdstring-with-a-custom-allocator

问题 I am working with an external library (pcl) so I need a solution that does not change the existing function prototypes. One function that I am using generates an std::vector<int, Eigen::aligned_allocator<int>> . The function that I want to call next expects a const boost::shared_ptr<std::vector<int, std::allocator<int>>> . I do not want to copy the elements because it is in an already slow critical part of my code. If not for the allocator mismatch, I would get around the shared_ptr

问题 There were a couple of great answers about the copy-and-swap idiom, e.g., explaining the copy and swap idiom and explaining move semantics. The basic idiom working for both copy and move assignment looks like this: T& T::operator=(T other) { this->swap(other); return *this; } This assignment works for both copy and move assignment because other is copy or move constructed depending on whether the right hand side of the assignment is an lvalue or an rvalue. Now let's have stateful allocators

问题 There were a couple of great answers about the copy-and-swap idiom, e.g., explaining the copy and swap idiom and explaining move semantics. The basic idiom working for both copy and move assignment looks like this: T& T::operator=(T other) { this->swap(other); return *this; } This assignment works for both copy and move assignment because other is copy or move constructed depending on whether the right hand side of the assignment is an lvalue or an rvalue. Now let's have stateful allocators