如何:具有默认值的c ++函数指针 [英] Howto: c++ Function Pointer with default values

问题描述

我有:

typedef void (*RespExtractor) (const cv::Mat & image, cv::Mat & resp);

virtual void predict_image(const cv::Mat & src,
            cv::Mat & img_detect,cv::Size patch_size,
            RespExtractor );

void create_hough_features(const cv::Mat & image, cv::Mat & resp, FeatureParams & params =   FeatureParams() );

我如何定义RespExtractor以接受具有默认参数的函数，例如我可以调用:

How would i define the RespExtractor to accept a function with default parameters, such i can call:

predict_image(im_in,im_out,create_hough_features);

我尝试了以下操作，但没有成功:

I tried following, with no succes:

typedef void (*RespExtractor) (const cv::Mat & image, cv::Mat & resp,FeatureParams params, FeatureParams()); 

推荐答案

函数指针本身不能具有默认值.您要么必须通过函数指针将调用包装在确实具有默认参数的函数中(这甚至可以是包装函数指针并具有带有默认参数的operator()的小类)，或者具有不同的函数指针针对您的函数的不同重载.

Function pointers themselves can't have default values. You'll either have to wrap the call via the function pointer in a function that does have default parameters (this could even be a small class that wraps the function pointer and has an operator() with default paremeters), or have different function pointers for the different overloads of your functions.

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