A design question -

John Tadar <john.tadar@gmail.com>
Fri, 5 Feb 2010 13:48:59 CST

I am quite new to C++ and am adding some new features to a library and
to some programs that call it. This library is our common one and is
used by all programs at our site. The new feature which I am adding is
only being used by a single program. But whenever the call reaches the
library and it reaches every so often, it must try to invoke this new
feature if its available.

I thought I will define a base class in the library which is more of
an interface. And whenever this feature is added in the various
programs, I would derive a new class specific to the program
functionality. And in each of these programs this has to be a
In the library:

class Base{


static Base * getInstance() { return sp; /* assume that its returned
thread safe */}
virtual void runTerm(){}

static atomic_refBase * sp;
string msg1;


Base * Base::sp = NULL;

In the library to invoke this feature:

Base * bp = Base::getInstance();
if( bp != NULL){


Now in the various programs:

class Derived : public Base{

  Base * getInstance(){ /* here implement a singleton and assign the
pointer to it to sp */

  void runTerm() { /*implement functionality specific to this program*/


Now my question is - is there a better way to do this? What may be the
pitfalls in this?

The programs where this gets implemented are all multi threaded


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