为什么我不能放一个“使用"?类声明中的声明?
我理解将 using 声明放入头文件时可能会遇到的麻烦，所以我不想这样做.相反，我尝试将 using(或 命名空间 foo =)放在类声明中，以减少头文件中的重复输入.不幸的是，我收到编译器错误.看起来这将是一个有用的功能.
I understand the troubles you can get into when you put a using declaration inside a header file, so I don't want to do that. Instead I tried to put the using (or a namespace foo =) within the class declaration, to cut down on repetitive typing within the header file. Unfortunately I get compiler errors. Seems like it would be a useful feature.
#ifndef FOO_H
#define FOO_H
// This include defines types in namespace gee::whiz::abc::def,
// such as the class Hello.
#include "file_from_another_namespace.h"
// using namespace gee::whiz::abc::def; // BAD!
namespace x {
namespace y {
namespace z {
struct Foo {
using namespace gee::whiz::abc::def; // Illegal.
namespace other = gee::whiz::abc::def; // Illegal.
// Foo(gee::whiz::abc::def::Hello &hello); // annoyingly long-winded
Foo(other::Hello &hello); // better
//...
};
} } } // end x::y::z namespace
#endif // FOO_H
在实际代码中，命名空间名称要长得多且烦人，而且我无法更改.
In the real code, the namespace names are much longer and annoying and it's not something I can change.
谁能解释为什么这不合法，或者(更好)是否有解决方法?
Can anyone explain why this is not legal, or (better) if there's a workaround?
推荐答案
你能做 typedef gee::whiz::abc::def::Hello Hello 吗?
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