在自定义分配器中,一般不需要手动实现construct和destroy,因为标准库中的std::allocator_traits会处理这些工作。std::allocator_traits默认会使用placement new来调用对象的构造函数,并调用对象的析构函数。 相当于在CustomAllocator中增加以下函数: template<typenameU,typename... Args>voidconstruct(U* p, Args&&... ...
template <typename T> class CustomAllocator { public: using value_type = T; using size_type = std::size_t; using difference_type = std::ptrdiff_t; CustomAllocator() = default; ~CustomAllocator() = default; template <typename U> CustomAllocator(const CustomAllocator<U>&) noexcept {} T*...
分配器（allocator）：用于分配和释放控制块和对象的内存的分配器，通常是std::allocator。引用计数（Refer...
std::shared_ptr<int> p4 (newint, std::default_delete<int>()); std::shared_ptr<int> p5 (newint, [](int* p){delete p;}, std::allocator<int>()); std::shared_ptr<int>p6 (p5); std::shared_ptr<int>p7 (std::move(p6)); std::shared_ptr<int> p8 (std::unique_ptr<int>(n...
* the allocator (type-erased); * the number of shared_ptrs that own the managed object; * the number of weak_ptrs that refer to the managed object. When shared_ptr is created by calling std::make_shared or std::allocate_shared, the memory for both the control block and the managed...
指定Allocator的inplace构造:通过自定义Allocator管理计数对象和实际对象的内存,通过placement new构造对象。( 自定义分配器, allocate_shared/allocate_strong_rc 的构造方式)boost::shared_ptr 的实现有问题,某些地方显示使用 new/delete 操作符了,导致对自定义Allocator没有完整的支持。 指定Allocator的带自定义Deletor的...
the allocator (type-erased); the number of shared_ptrs that own the managed object; the number of weak_ptrs that refer to the managed object. When shared_ptr is created by calling std::make_shared or std::allocate_shared, the memory for both the control block and the managed object...
allocate_sharedallocate_shared_for_overwrite (C++20) creates a shared pointer that manages a new object allocated using an allocator (function template) enable_shared_from_this (C++11) allows an object to create ashared_ptrreferring to itself (class template)...
Define custom allocator for std::shared_ptr For introducing memory pool in my project, we can define a custom allocator for std::shared_ptr, overrided the allocate and deallocate methods, then we can make shared_ptr by the std::allocate_shared: std::allocate_shared<T>(custom_alloc, std:...
4)同(3),但额外地用alloc的副本分配内部使用的数据。Alloc必须是分配器(Allocator)。复制构造函数和析构函数必须不抛异常。等价于shared_ptr<T>(ptr, d, alloc).swap(*this);。 参数 ptr-指向要取得所有权的对象的指针 d-为删除对象而存储的删除器 ...