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POC++ callback for non-static function between different classes
 

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  1. POC++ callback for non-static function between different classes
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    <p>I have a Class A which I intend to put in a shared library as it interacts with the device drivers.</p> <p>I have a Class B and may be C,D,E... in future which will use the class A using the shared library.</p> <p>I want a capability of setting a callback function in Class A so that when a specific event occurs a non-static members function of class B,C,D,E ... should be called by Class A.</p> <p>I searched on google for callback function in C++ but found that non-static member functions are not supported by C-style definition of callbacks.</p> <p>Can it be done using function pointers ?</p> <p>Kindly give some suggestions for callbacks in C++ which do not violate the OOPS concepts.</p> <p>I also came around a library called 'Boost' which offers similar functionality but I want to avoid the overhead of the extra library if possible. Is Boost recommended for callback function ?</p> <p><strong>EDIT :</strong> The B,C,D,E will not share any hierarchy and they will be completely independent classes. But all of them would have object of class A. And class A would also have a public function to set the callback function.</p>
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    1. COA non-static member function has to be called upon a concrete object of class B, C, .... Not sure what you are after. If I understand correctly, your system interact with object of class A without knowledge of class B, C, D. Then it is impossible to have A call a non-static member of B, etc unless either B derived from A, and the system interact with a B class object through A pointer, by virtual functions or CRTP; Or A has a B class sub object. Either way, your system has to know a B class concrete object to call its non-static member
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    2. COThe class A will provide a mechanism (public function) to set the callback function. And class B,C,... will also have a object of class A. So, after the class B,C,.. has set the function and after a particular event is detected by class A, the class A should be able to call the function set by B,C,...
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    3. COI think it is impossible. If {B, C, ...} does not share some hierarchy, for example, all derived from A, how could A know which type of the object the callback shall be called upon? You can pass member function pointers to A, but A need to know the type B to call it. If A has B or C, etc, then it will be possible. But it is not the case in your question.
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