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Possible Duplicate:
Why are redundant scope qualifications supported by the compiler, and is it legal?
我不希望它能编译，但它确实编译了。这可能是编译器错误，还是它有一些正确的含义？
$ g++ -c scopes.cpp
$ cat scopes.cpp
class Log {
public:
Log() { }
static void fn() { }
};
void test() {
Log::Log::Log::Log::Log::Log::fn();
}
$ g++ --version
g++ (Ubuntu 4.4.3-4ubuntu5.1) 4.4.3
最佳答案
是的，这是合法的。一个类的名称被插入到它自己的 namespace 中，称为注入(inject)类名称。来自 C++03 §9/2:
[...] The class-name is also inserted into the scope of the class itself; this is known as the injected-class-name. For purposes of access checking, the injected-class-name is treated as if it were a public member name.
请注意，Log::Log 命名了类构造函数，这仅在某些上下文中允许，但只要您结束 Log::Log::... 使用 Log 以外的东西(例如 fn)，那么它不会命名构造函数。具体来说，§3.4.3.1/1a 说:
If the nested-name-specifier nominates a class
C, and the name specified after the nested-name-specifier, when looked up inC, is the injected-class-name ofC(clause 9), the name is instead considered to name the constructor of classC. Such a constructor name shall be used only in the declarator-id of a constructor definition that appears outside of the class definition.
关于c++ - 可以指定重复的 C++ 类作用域吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12843893/