C ++中的命名参数字符串格式化 [英] Named parameter string formatting in C++

问题描述

我想知道是否有一个类似Boost格式的库，但支持命名参数，而不是位置。这是一个常见的成语。 Python，你有一个上下文来格式化字符串，可能使用或不使用所有可用的参数，例如

I'm wondering if there is a library like Boost Format, but which supports named parameters rather than positional ones. This is a common idiom in e.g. Python, where you have a context to format strings with that may or may not use all available arguments, e.g.

mouse_state = {}
mouse_state['button'] = 0
mouse_state['x'] = 50
mouse_state['y'] = 30

#...

"You clicked %(button)s at %(x)d,%(y)d." % mouse_state
"Targeting %(x)d, %(y)d." % mouse_state

有没有任何库提供最后两行的功能？我希望它提供一个API类似：

Are there any libraries that offer the functionality of those last two lines? I would expect it to offer a API something like:

PrintFMap(string format, map<string, string> args);

在Googling中，我发现许多库提供了位置参数的变体，但没有一个支持命名的。理想情况下，库有很少的依赖，所以我可以轻松放入我的代码。 C ++不会像收集命名参数一样习惯，但是可能有人比我想象的更多。

In Googling I have found many libraries offering variations of positional parameters, but none that support named ones. Ideally the library has few dependencies so I can drop it easily into my code. C++ won't be quite as idiomatic for collecting named arguments, but probably someone out there has thought more about it than me.

性能很重要，特别是我喜欢保持内存分配下降（总是棘手的C ++），因为这可以在没有虚拟内存的设备上运行。

Performance is important, in particular I'd like to keep memory allocations down (always tricky in C++), since this may be run on devices without virtual memory. But having even a slow one to start from will probably be faster than writing it from scratch myself.

推荐答案

答案似乎是： ，没有，没有一个C ++库这样做，而C ++程序员显然甚至不需要一个，基于我收到的意见。我必须再写一遍。

The answer appears to be, no, there is not a C++ library that does this, and C++ programmers apparently do not even see the need for one, based on the comments I have received. I will have to write my own yet again.

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