c++ convert class to boolean

Question

With all of the fundamental types of C++, one can simply query:

if(varname)

and the type is converted to a boolean for evaluation. Is there

Answer 1

As others have stated, using operator int () or operator bool () is bad idea because of the conversions it allows. Using a pointer is better idea. The best know solution to this problem so far is to return a member (function) pointer:

class MyClass {
  void some_function () {}

  typedef void (MyClass:: * safe_bool_type) ();
  operator safe_bool_type () const
  { return cond ? &MyClass::some_function : 0; }
};