Callback without function pointer

Question

It is usually said callbacks are implemented with function pointers. When I check PortAudio's source code, I see that callback function is declared as an ordinary function (not a f. pointer). Is it normal/legal/advisable?

typedef int PaStreamCallback(
const void *input, void *output,
unsigned long frameCount,
const PaStreamCallbackTimeInfo* timeInfo,
PaStreamCallbackFlags statusFlags,
void *userData );

kennytm · Accepted Answer · 2010-08-13 08:17:28Z

4

It is fine as long as the parameter is used as PaStreamCallback* (which is a pointer to a function), like

PaError Pa_OpenStream   (
        PaStream **      stream,
        const PaStreamParameters *      inputParameters,
        const PaStreamParameters *      outputParameters,
        double      sampleRate,
        unsigned long   framesPerBuffer,
        PaStreamFlags   streamFlags,
        PaStreamCallback *      streamCallback,   // <---
        void *      userData     
    )

answered Aug 13, 2010 at 8:17

kennytm

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2 Comments

user192936 Over a year ago

ok, thanks. by the way, the functions are passed to Pa_OpenStream with their names only, however logically must be passed with addressof operator, but omitting & is a shortcut, right?

kennytm Over a year ago

@paul if foo is a function, foo and &foo are equivalent.

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