23 General utilities library [utilities]

23.12 Memory resources [mem.res]

23.12.4 Access to program-wide memory_­resource objects [mem.res.global]

memory_resource* new_delete_resource() noexcept;
Returns: A pointer to a static-duration object of a type derived from memory_­resource that can serve as a resource for allocating memory using ​::​operator new and ​::​operator delete.
The same value is returned every time this function is called.
For a return value p and a memory resource r, p->is_­equal(r) returns &r == p.
memory_resource* null_memory_resource() noexcept;
Returns: A pointer to a static-duration object of a type derived from memory_­resource for which allocate() always throws bad_­alloc and for which deallocate() has no effect.
The same value is returned every time this function is called.
For a return value p and a memory resource r, p->is_­equal(r) returns &r == p.
The default memory resource pointer is a pointer to a memory resource that is used by certain facilities when an explicit memory resource is not supplied through the interface.
Its initial value is the return value of new_­delete_­resource().
memory_resource* set_default_resource(memory_resource* r) noexcept;
Effects: If r is non-null, sets the value of the default memory resource pointer to r, otherwise sets the default memory resource pointer to new_­delete_­resource().
Returns: The previous value of the default memory resource pointer.
Remarks: Calling the set_­default_­resource and get_­default_­resource functions shall not incur a data race.
A call to the set_­default_­resource function shall synchronize with subsequent calls to the set_­default_­resource and get_­default_­resource functions.
memory_resource* get_default_resource() noexcept;
Returns: The current value of the default memory resource pointer.