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std::pmr::polymorphic_allocator::new_object(3) C++ Standard Libary std::pmr::polymorphic_allocator::new_object(3)

NAME

std::pmr::polymorphic_allocator::new_object - std::pmr::polymorphic_allocator::new_object

Synopsis


template< class U, class... CtorArgs > (since C++20)
[[nodiscard]] U* new_object( CtorArgs&&... ctor_args );


Allocates and constructs an object of type U.


Given alloc is a std::pmr::polymorphic_allocator<T>:


U* p = alloc.new_object<U>(std::forward<CtorArgs>(ctor_args)...);


is equivalent to


U* p = alloc.allocate_object<U>();
try {
alloc.construct(p, std::forward<CtorArgs>(ctor_args)...);
} catch (...) {
alloc.deallocate_object(p);
throw;
}

Parameters


ctor_args - the arguments to forward to the constructor of U

Return value


A pointer to the allocated and constructed object.

Notes


This function was introduced for use with the fully-specialized allocator
std::pmr::polymorphic_allocator<>, but it may be useful in any specialization as a
shortcut to avoid having to rebind from std::pmr::polymorphic_allocator<T> to
std::pmr::polymorphic_allocator<U>, and having to call allocate, construct, and
deallocate individually.


Since U is not deduced, it must be provided as a template argument when calling this
function.

Exceptions


May throw any exceptions thrown by the call to allocate_object or the constructor of
U.

See also


allocate_bytes Allocate raw aligned memory from the underlying resource
(C++20) (public member function)
allocate_object Allocates raw memory suitable for an object or an array
(C++20) (public member function)
allocate Allocate memory
(public member function)
allocate allocates uninitialized storage using the allocator
[static] (public static member function of std::allocator_traits<Alloc>)
allocate allocates memory
(public member function of std::pmr::memory_resource)

2022.07.31 http://cppreference.com