ios - libdispatch(apple-open-source)中的这段代码是什么意思？

Question

我很难理解下面的代码:

struct dispatch_block_private_data_s {
    DISPATCH_BLOCK_PRIVATE_DATA_HEADER();
    static void* operator new(size_t) = delete;
    static void* operator new [] (size_t) = delete;
    explicit inline DISPATCH_ALWAYS_INLINE dispatch_block_private_data_s(
            dispatch_block_flags_t flags, voucher_t voucher,
            pthread_priority_t priority, dispatch_block_t block) noexcept :
            dbpd_magic(), dbpd_flags(flags), dbpd_atomic_flags(),
            dbpd_performed(), dbpd_priority(priority), dbpd_voucher(voucher),
            dbpd_block(block), dbpd_group(), dbpd_queue(), dbpd_thread()
    {
        // stack structure constructor, no releases on destruction
        _dispatch_block_private_data_debug("create, block: %p", dbpd_block);
    }
};

什么是 static void* operator new(size_t) = delete; 以及为什么 inline func 在 struct 中？谁能帮我学习这些代码？这是 code address

Answer 1

注意 .cpp 扩展名。这是 C++代码。

1. operator ... = delete 语法表明应该禁止此运算符，如果您尝试使用它，则会生成编译器警告。

2. inline 限定符是一种性能优化。引用自The C++ Programming Language :

   The inline specifier is a hint to the compiler that it should attempt to generate code for a call of [the function] inline rather than laying down the code for the function once and then calling through the usual function call mechanism.

   如果(a)一个函数很小； (b) 性能是最重要的，您可以使用 inline 限定符，这样编译器将有效地在您使用函数的任何地方插入函数代码，而不是将其保存为函数并调用你通常会这样做。这节省了调用函数的适度开销。

如果您在理解 C++ 方面需要帮助，我建议您查看 these resources .