functor - Function pointers in embedded systems, are they useful?

Question

In an interview they asked me if using function pointers would be beneficial (in terms of speed) when writing code for embedded systems? I had no idea on embedded system so could not answer the question. Just a cloudy or vague answer. So what are the real benefits? Speed, readability, maintenance,cost?

Answer 1

I think perhaps Viren Shakya's answer misses the point that the interviewer was trying to elicit. In some constructs the use of a function pointer may speed up execution. For example, if you have an index, using that to index an array of function pointers may be faster than a large switch.

If however you are comparing a static function call with a call through a pointer then Viren is right in pointing out that there is an additional operation to load the pointer variable. But no one reasonably tries to use a function pointer in that way (just as an alternative to calling directly).

Calling a function through a pointer is not an alternative to a direct call. So, the question of "advantage" is flawed; they are used in different circumstances, often to simplify other code logic and control flow and not to merely avoid a static function call. Their usefulness is in that the determination of the function to be called is performed dynamically at run-time by your code rather than statically by the linker. In that sense they are of course useful in embedded systems but not for any reason related to embedded systems specifically.