将C ++成员函数映射到C回调

问题描述

在C ++项目中，我使用C库访问一些硬件。 C-Bindings包括回调以通知一些输入引脚上的更改。
回调函数看起来像这样：
void callback（char port，uint8_t interrupt_mask，uint8_t value_mask，void * user_data）

In a C++ project I am using a C library to access some hardware. The C-Bindings include callbacks to notify about changes on some input pins.The function for the callback looks like this:void callback(char port, uint8_t interrupt_mask, uint8_t value_mask, void *user_data)

在我的实现中，我有一个 SensorController 类，它有一个成员函数应该接收回调。成员函数看起来像这样 void SensorController :: pinChanged（char port，uint8_t interrupt_mask，uint8_t value_mask，void * user_data）。

In my implementation I have a SensorController class which has a member function that should receive the callback. The member function looks like this void SensorController::pinChanged(char port, uint8_t interrupt_mask, uint8_t value_mask, void *user_data).

现在我想知道，什么是最简单的方法，避免使 pinChanged function static能够将函数分配给回调？

Now I was wondering, what would be the cleanest way to avoid making the pinChanged function static to be able to assign the function to the callback?

推荐答案

使用 user_data 指针返回指向拥有回电话。例如

Use the user_data pointer to give you back a pointer to the class that owns the callback. For example.

void MyCallback(char port, uint8_t interrupt_mask, uint8_t value_mask, void *user_data)
{
    static_cast<Example *>(user_data)->Callback(port, interrupt_mask, value_mask);
}

class Example
{
public:

    Example()
    {
        //setup callback here - i dont know what library you're using but you should be able to pass a this pointer as user_data
        init_lib(fictionalparameter1, fictionalparameter2, this);
    }

private:

     void   Callback(char port, uint8_t interrupt_mask, uint8_t value_mask)
     {
         //callback handler here...
     }

     friend void MyCallback(char port, uint8_t interrupt_mask, uint8_t value_mask, void *user_data);
};

这篇关于将C ++成员函数映射到C回调的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！