C++中的一个定义规则到底是什么? [英] What exactly is One Definition Rule in C++?

问题描述

C++ 中的一个定义规则到底说的是什么?我能找到的唯一值得信赖的出现在 The C++ Programming Language, 3rd.编，第 9.2.3 页.除此以外，是否还有其他正式的规则定义?

What exactly does One Definition Rule in C++ say? The only trustworthy occurence I can find is in The C++ Programming Language, 3rd. ed., P. 9.2.3. Is there any official definition of the rule except that?

推荐答案

真理在标准中(3.2一定义规则):

The truth is in the standard (3.2 One definition rule) :

任何翻译单元不得包含更多不是任何变量的一个定义，函数、类类型、枚举类型或模板.

No translation unit shall contain more than one definition of any variable, function, class type, enumeration type or template.

[...]

每个程序都应准确包含每个非内联的一个定义中使用的函数或对象 那个程序；无需诊断.定义可以显式出现在程序中，它可以在标准或用户定义的库，或(在适当的时候)它是隐含的定义(见 12.1、12.4 和 12.8).一个内联函数应定义在它所在的每个翻译单元用过.

Every program shall contain exactly one definition of every non-inline function or object that is used in that program; no diagnostic required. The definition can appear explicitly in the program, it can be found in the standard or a user-defined library, or (when appropriate) it is implicitly defined (see 12.1, 12.4 and 12.8). An inline function shall be defined in every translation unit in which it is used.

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