C++核心准则C.81:如果不需要默认（同时不需要其他选项）行为，使用=delete禁止它们

C++核心准则C.81:如果不需要默认（同时不需要其他选项）行为，使用=delete禁止它们

C.81: Use =delete when you want to disable default behavior (without wanting an alternative)

C.81:如果不需要默认（同时不需要其他选项）行为，使用=delete禁止它们

Reason（原因）

In a few cases, a default operation is not desirable.

某些情况下·，也有可能·不希望存在默认行为。

Example（示例）

class Immortal {public: ~Immortal() = delete; // do not allow destruction // ...};void use(){ Immortal ugh; // error: ugh cannot be destroyed Immortal* p = new Immortal{}; delete p; // error: cannot destroy *p}

Example（示例）

A unique_ptr can be moved, but not copied. To achieve that its copy operations are deleted. To avoid copying it is necessary to =delete its copy operations from lvalues:

template > class unique_ptr {public: // ... constexpr unique_ptr() noexcept; explicit unique_ptr(pointer p) noexcept; // ... unique_ptr(unique_ptr&& u) noexcept; // move constructor // ... unique_ptr(const unique_ptr&) = delete; // disable copy from lvalue // ...};unique_ptr make(); // make "something" and return it by movingvoid f(){ unique_ptr pi {}; auto pi2 {pi}; // error: no move constructor from lvalue auto pi3 {make()}; // OK, move: the result of make() is an rvalue}

Note that deleted functions should be public.

注意：禁止的函数应该是公有的。

----Effective Modern C++

Enforcement（实施建议）

The elimination of a default operation is (should be) based on the desired semantics of the class. Consider such classes suspect, but maintain a "positive list" of classes where a human has asserted that the semantics is correct.

消除默认操作（应该）应该基于类的期待语义。怀疑这些类，但同时维护类的“正面清单”，其内容是由人断定是正确的东西。

原文链接

​​https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c81-use-delete-when-you-want-to-disable-default-behavior-without-wanting-an-alternative​​

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