什么是“问题"?可变的预选赛位置? [英] What is "the issue" with variable qualifier placement?

问题描述

在此文档中在标有变量限定符"的部分下，苹果说:

In this document, under the section labeled "Variable Qualifiers", Apple says:

您应该正确修饰变量.在对象变量声明中使用限定符时，正确的格式为:

You should decorate variables correctly. When using qualifiers in an object variable declaration, the correct format is:

ClassName * qualifier variableName;

例如:

MyClass * __weak myWeakReference;
MyClass * __unsafe_unretained myUnsafeReference;

其他变体在技术上不正确，但被编译器原谅".要了解此问题，请参见 http://cdecl.org/.

看cdecl.org并不能澄清任何事情.谁能解释他们所指的问题"?换句话说，请帮助我说服其他人，这实际上很重要，而不仅仅是因为这个自述文件这么说."

Looking at cdecl.org doesn't clarify anything. Can anyone explain what "the issue" they are referring to is? In other words, help me convince others that this actually matters in a way that isn't just "because this one readme says so."

推荐答案

查看我的带有乱码的英语翻译示例

See my examples with gibberish to English translations

众所周知，

ClassName * const varName; //varName is a constant pointer to ClassName

与

const ClassName * varName; //varName is a pointer to constant ClassName

或

ClassName const * varName; //varName is a pointer to constant ClassName

以同样的方式声明

ClassName * __weak varName; //varName is a weak pointer to ClassName

此声明

__weak ClassName * varName; //varName is a pointer to weak?? ClassName??

非常不同.但是，第二个含义很明确(尽管从技术上讲是不正确的)，编译器可以原谅".

are VERY different. However, the meaning of the second one is clear (although it's technically incorrect) and it can be "forgiven" by the compiler.

一旦您开始使用指向指针的指针(例如Foo * __autoreleasing *)，正确性就变得更为重要.

The correctness is a bit more important once you start working with pointers to pointers (e.g. Foo * __autoreleasing *).

我认为他们想保护初学者免受C/C ++声明的干扰.一开始就有预选赛似乎很自然.

I assume they wanted to protect beginner developers from the C/C++ declaration gibberish. Having the qualifier in the beginning seems more natural.

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