Question

class AbstractQuery {     virtual bool isCanBeExecuted()=0; public:     AbstractQuery() {}     virtual bool Execute()=0; };  class DropTableQuery: public AbstractQuery {     vector< std::pair< string, string> > QueryContent;     QueryValidate qv; public:     explicit DropTableQuery(const string& qr): AbstractQuery(), qv(qr) {}     bool Execute(); }; 

Is it necessary to call base contructor in derived class constructor?

Answer 1

No, in fact for it is unnecessary for the base class to have an explicitly defined constructor (though make sure you have a virtual destructor).

So for a typical interface you could have something like this:

class MyInterface { public:     virtual ~MyInterface() {}     virtual void execute() = 0; }; 

EDIT: Here’s a reason why you should have a virtual destructor:

MyInterface* iface = GetMeSomeThingThatSupportsInterface(); delete iface; // this is undefined behaviour if MyInterface doesn't have a virtual destructor