此宏有什么问题? [英] What is wrong with this Macro?

问题描述

#define mySynthesize(op) @synthesize op = _op;

所以不要输入

@synthesize someVar=_someVar;
@synthesize otherVar=_otherVar;

我可以做

mySynthesize (someVar);

好吧，虽然没有用.我做错了什么?

Well, it doesn't work though. What did I do wrong?

推荐答案

为op加上下划线前缀时，预处理器会将其视为其他令牌，因此不会被替换.您需要使用##将下划线连接到前面，以便首先进行替换.

When you prefix the op with an underscore, the preprocessor treats it as a different token, so it doesn't get replaced. You need to use ## to concatenate the underscore to the front so that the replacement occurs first.

#define mySynthesize(op) @synthesize op = _ ## op

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