Why is no qualification necessary?

Question

OK, I\'ll just post the complete program even though it has extraneous stuff and the code in question is the dead code…

#include 
#include         


        

Answer 1

Some thoughts about why you have to specify std::ifstream in constructor's initializer . I think typedef is the culprit - ifstream is defined as typedef basic_ifstream > ifstream;). If you change your constructor to

 explicit InFStream(
    char const*         filename,
    ios_base::openmode  mode =  ios_base::in | ios_base::out

    ):
    basic_ifstream>( filename, mode ){}

you also don't have to specify std::basic_ifstream. I cannot find details about why typedef works this way, but the problem is reproducible. For instance,

namespace test1
{
class A {

public :
    static const int cn = 1;

    virtual ~A();
    A(int t): x(t){};
    int x;
};

class B:public A
{
public:
    B(int t) : A(t){};
};
typedef B XX;  
};  
class C:public test1::XX
{
  int aaa;
    public:
explicit  C(int x) :XX(x) // error  
explicit  C(int x) :test1::XX(x) // ok
explicit  C(int x) :B(x) // also ok
{       
    aaa = A::cn;
};
};