From: paul DOT bibbings AT tesco DOT net (Paul Bibbings)
Newsgroups: comp.os.msdos.djgpp
Subject: DJGPP - failure to implement namespaces properly
Date: Tue, 11 Jul 2000 14:52:25 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Don't get me wrong, as a novice C++ programmer I have no doubt that
DJGPP/Rhide is my favourite compiler/IDE combination, and that is why
I am all the more frustrated when it seems it doesn't implement the
language in ways the textbooks would expect it to. Maybe I'm missing
something (and I apologise if that's the case) but it seems to me
DJGPP can get all at sea with namespaces, and in particular with the
use of using declarations. I have come across many instances of this,
and currently I have been stumped by the fact that it will not allow
me to using using declarations to implement overloaded functions
across base/derived class boundaries.
	The following snippet, adapted from Stroustrup (3rd ed) 15.2.2
simply won't compile.


#define nonstandard

#include <iostream>
#include <cstdlib>

#ifdef nonstandard
#include <conio.h>
#endif

using std::cout;
using std::endl;

class A{
   int i;
   char c;
public:
   A(): i(0), c(0) {}
   A(int ii): i(ii), c(0) {}
   A(char cc): i(0), c(cc) {}
   A(int ii, char cc): i(ii), c(cc) {}
   int get_int() const {return i;}
   char get_char() const {return c;}
   int f(int ii) {cout << "In A::f(int)..." << endl; return 2 * i;}
   char f(char c) {return i;}  // implicit cast int to char
};

class B{
   double d;
public:
   B(double dd = 0): d(dd) {}
   double get_double() const {return d;}
   double f(double dd) {return d/2;}
};

class AB: public A, public B{
public:
   AB(int ii = 0, char cc = 0, double dd = 0): A(ii, cc), B(dd) {}
   using A::f;  //*******************************  problem
   using B::f;  //*******************************  lines
   char f(char c) {return c;}  // hides a::f(char)
   AB f(AB);   // line 52
};

int main()
{
   cout << "Token main()..." << endl;

   return EXIT_SUCCESS;
}


failing with the error messages

C:\c++projs\inherit_using.cpp:53: cannot adjust access to `char
A::f(char)' in `class AB'
C:\c++projs\inherit_using.cpp:52:   because of local method `class AB
AB::f(AB)' with same name
C:\c++projs\inherit_using.cpp:53: cannot adjust access to `double
B::f(double)' in `class AB'
C:\c++projs\inherit_using.cpp:52:   because of local method `class AB
AB::f(AB)' with same name

Process completed with exit code 1

This seems like a significant failing on the compiler's part, since
the technique of overloading across inheritance boundaries is
something I, at least, can imagine using often.