C ++模板是伪装的宏吗？ [英] Are C++ Templates just Macros in disguise?

问题描述

我已经在C ++中编程了几年，我已经使用STL了很多，并创建了自己的模板类几次，看看它是如何做。

I've been programming in C++ for a few years, and I've used STL quite a bit and have created my own template classes a few times to see how it's done.

现在我正在尝试将模板更深入地集成到我的OO设计中，一个ging叨的想法不断回到我：他们只是一个宏，真的...你可以实现（而不是UGLY）auto_ptrs使用＃

Now I'm trying to integrate templates deeper into my OO design, and a nagging thought keeps coming back to me: They're just a macros, really... You could implement (rather UGLY) auto_ptrs using #defines, if you really wanted to.

这种思考模板的方式帮助我理解我的代码如何工作，但我觉得我必须在某种程度上错过这一点。宏是指邪恶的化身，但模板元编程是所有愤怒。

This way of thinking about templates helps me understand how my code will actually work, but I feel that I must be missing the point somehow. Macros are meant evil incarnate, yet "template metaprogramming" is all the rage.

那么，真正的区别是什么？如何避免#define引起的危险，例如

So, what ARE the real distinctions? and how can templates avoid the dangers that #define leads you into, like

• 
  中的Inscrutable编译器错误， t期望他们？


• 代码膨胀？


• 难以跟踪代码？


• 设置调试器断点？

• Inscrutable compiler errors in places where you don't expect them?
• Code bloat?
• Difficulty in tracing code?
• Setting Debugger Breakpoints?

推荐答案

宏是一种文本替换机制。

Macros are a text substitution mechanism.

模板是一种功能完备的语言，并集成到C ++类型系统中。您可以将它们视为语言的插件机制。

Templates are a functional turing-complete language that is executed at compile time and is integrated into the C++ type system. You can think of them as a plugin mechanism for the language.

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