Initialize const member variables

Question

I have C++ code that boils down to something like the following:

class Foo{
    bool bar;
    bool baz;
    Foo(const void*);
};
Foo::Foo(const void* ptr){
          


        

Answer 1

If you don't want to use the newfangled delegating constructors (I still have to deal with compiler versions that don't know about them), and you don't want to change the layout of your class, you could opt for a solution that replaces the constructor with const void * argument by a static member function returning Foo, while having a private constructor that takes the output from complex_method as argument (that latter much like the delegating constructor examples). The static member function then does the necessary preliminary computation involving complex_method, and ends with return Foo(s);. This does require that the class have an accessible copy constructor, even though its call (in the return statement) can most probably be elided.