This isn't a gcc question. It's a c++ question.
Your code can be fixed with a using declaration to change the
protection of the enum "Alpha" and member "alpha".
On Wed, Dec 4, 2013 at 8:51 AM, Graziano Servizi
<Graziano.Servizi@xxxxxxxxxx> wrote:
> Dear Jonathan, Dietmar or anybody else,
>
> I'm doing some exercises and I tried enum class as a type embedded in a
> class scope which is the ancestor of a two-level hierarchy.
>
> My aim was to use bool as underlying type, and this was accepted by the
> compiler...
>
> Nevertheless, transmitting a value for a member variable of the enum class
> type through the chain of constructors, I found it finally changed
> without any evident reason, even if it had the value I expected during its
> whole history.
>
> There should be something wrong in my code I can't find, and your help would
> be highly appreciated.
>
>
> Here follows the code: it is, I hope, short enough to be easily debugged. As
> you can see main declares an object of class Third and
> thereafter ask for the value returned by its giveMe public method.
>
> The Third's ctor sends a value up to the constructor of the ancestor
> class, which uses it to initialize a member variable, which, in my
> opinion should be inherited by Third.
>
> But the value written is the opposite I expected...Why?
>
> ///////// code
> # include <iostream>
> using namespace std;
>
> class First
> {public:
> enum class Alpha : bool {A=false, B=true};
> protected:
> Alpha alpha;
> First(Alpha b)
> {alpha = b;
> clog << "First's ctor set " << static_cast<bool>(alpha) << endl;}
> };
>
> class Second : First
> {
> protected:
> Alpha First :: alpha; // to reset from private
> public:
> First :: Alpha; // to reset Alpha type as public
> Second(Alpha b) : First(b)
> {
> clog << "Second's ctor handles " << static_cast<bool>(b) << endl;
> }
> };
>
> class Third : Second
> {
> public:
> Alpha giveMe() // Alpha is recognized without scope resolution (by
> inheritance...)
> {// alpha should be inherithed from First, through Second...or NOT?
> clog << "Second :: giveMe returns " << static_cast<bool>(alpha) << endl;
> return alpha;}
> Third(Alpha b = Alpha :: A) : Second(b)
> {
> clog << "Third's ctor handles " << static_cast<bool>(b) << endl;
> }
> };
>
> int main( )
> {
> Third aaa;
> clog << "in main one finds " << static_cast<bool>(aaa.giveMe()) << '\n';
> }
> ////////// end code
>
>
--
Andrew Bell
andrew.bell.ia@xxxxxxxxx
