为什么参数依赖查找发明？ [英] Why was argument dependent lookup invented?

问题描述

为什么参数依赖查找（ADL）发明？就是这样我们可以写 cout<< 如果是这样的话，为什么ADL不能限于操作符而不是所有的函数？

如果C ++有其他方法可以阻止ADL的引入例如通过可变参数模板的类型安全 printf ？通过可变参数模板，通用输出内置和用户定义的类型？

接口原理

>

对于类X，所有函数，包括自由函数，

• 提及X和


• 提供X

检查Herb Sutter的优秀

Why was argument dependent lookup (ADL) invented? Is it just so we can write cout << stuff instead of std::operator<<(cout, stuff)? If that is the case, why wasn't ADL limited to operators instead of all functions?

Could the introduction of ADL have been prevented if C++ had had some other way to do generic output of both built-in and user-defined types, for example a type-safe printf via variadic templates?

解决方案

ADL was invented to allow the Interface Principle:

The Interface Principle

For a class X, all functions, including free functions, that both

• "mention" X, and
• are "supplied with" X

are logically part of X, because they form part of the interface of X.

Check out Herb Sutter's excellent Guru of the Week on the topic.

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