将调用者__FILE__ __LINE__传递到函数而不使用宏 [英] Passing the caller __FILE__ __LINE__ to a function without using macro

问题描述

我习惯了：

  class Db {
 _Commit（char * file，int line） {
 Log（Commit from％s：％d，file，line）; 
} 
}; 
 
 #define Commit（）_Commit（__ FILE__，__LINE__）
  

大问题是我重新定义了 Commit 这个词，在一个400k行的应用程序框架中，这是一个问题。我不想使用像 DbCommit 这样的特定词：我不喜欢像 db-> DbCommit（），或者手动在任何地方传递值： db->提交（__ FILE__，__LINE __）是最差的。

解决方案

行信息，你宁愿不使用宏，对吧？

在一天结束时，它不能在C ++中完成。无论你选择什么机制 - 内联函数，模板，默认参数或其他东西 - 如果你不使用宏，你会得到文件名&

使用宏。

编辑：

即使 C++常见问题表示宏有时是两种邪恶的较小者。

EDIT2：

正如Nathon在下面的评论中所说的，在使用宏的情况下，最好是明确的。给你的宏宏名称，如 COMMIT（）而不是 Commit（）。这将使维护者&调试器有一个宏调用，它应该有助于在大多数情况下避免冲突。两件好事。

I'm used to this:

class Db {
  _Commit(char *file, int line) {
    Log("Commit called from %s:%d", file, line);
  }
};

#define Commit() _Commit(__FILE__, __LINE__)

but the big problem is that I redefine the word Commit globally, and in a 400k lines application framework it's a problem. And I don't want to use a specific word like DbCommit: I dislike redundancies like db->DbCommit(), or to pass the values manually everywhere: db->Commit(__FILE__, __LINE__) is worst.

So, any advice?

解决方案

So, you're looking to do logging (or something) with file & line info, and you would rather not use macros, right?

At the end of the day, it simply can't be done in C++. No matter what mechanism you chose -- be that inline functions, templates, default parameters, or something else -- if you don't use a macro, you'll simply end up with the filename & linenumber of the logging function, rather than the call point.

Use macros. This is one place where they are really not replaceable.

EDIT:

Even the C++ FAQ says that macros are sometimes the lesser of two evils.

EDIT2:

As Nathon says in the comments below, in cases where you do use macros, it's best to be explicit about it. Give your macros macro-y names, like COMMIT() rather than Commit(). This will make it clear to maintainers & debuggers that there's a macro call going on, and it should help in most cases to avoid collisions. Both good things.

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