Excessive use of inline functions might bloat the size of the executable and reduce execution speed. In other words, using inline abundantly can degrade rather than enhance performance. For this reason, many programmers avoid function inlining altogether because they can’t predict how inlining will affect performance. However, there is one guarantee: very short functions (e.g., a function that merely calls another function or a function that returns a data member of its object) are always good candidates for inlining. For example:

   inline bool Foo::is_connection_alive()  {     return ::connection_alive(); // calls an API function  }  inline int Bar::get_x()  {     return x; // merely returns a data member  }

By inlining such functions, the size of the executable decreases slightly and execution speed is boosted. Note, however, that this rule applies to very short functions exclusively. For larger functions, you usually need to profile the software with and without inline to assess the effects of inlining.