C ++，用lambda填充typedef吗? [英] C++, Fulfilling typedef with lambda?

问题描述

我有一个功能，例如:

typedef void(*timercallback)(void);
void timer1_attachInterrupt(timercallback userFunc);

我希望调用成员方法而不是C样式函数，因此我尝试了以下lambda:

I wish to call a member method rather than a C style function, so I have tried the following lambda:

timer1_attachInterrupt([this](void) -> void { _member_method(); });

但是我收到编译器错误:

However I get the compiler error:

没有合适的转换函数，从"lambda [] void()-> void"转换为 "timercallback"存在

No suitable conversion function from "lambda [] void () -> void" to "timercallback" exists

据我所知，lambda具有像typedef这样的void参数，并像tye​​pdef这样返回void.我想念什么?

As far as I can see, the lambda has void arguments like the typedef, and returns void like the tyepdef. What am I missing?

推荐答案

我想念什么?

What am I missing?

lambda创建一个闭包对象，因为它需要捕获状态.因此，您不能仅将其传递到需要常规函数指针的位置.

The lambda creates a closure object since it needs to capture state. Therefore you can't just pass it where a regular function pointer is expected.

由于您的API没有为将状态传递给回调做任何准备，因此您将需要使用诸如全局变量之类的令人讨厌的东西.

Since your API doesn't make any provisions for passing state to the callback, you will need to use something unpleasant like global variables.

如果您可以修改timer1_attachInterrupt ¹ ，那么我建议您允许它接受任何(类型擦除的)函子. std::function只是用于完成此任务的实用程序:

If you can modify timer1_attachInterrupt¹, then I suggest you allow it to accept any (type-erased) functor. std::function is just the utility to accomplish that:

using timercallback = void(void);
void timer1_attachInterrupt(std::function<timercallback> userFunc);

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_{¹ 很显然，OP无法在 arduino 进行修改.但我建议那些可能修改其功能的人使用.}

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_{¹It's quite clear the OP can't after the arduino edit. But I leave the suggestion for anyone who may be able to modify their functions.}

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