"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:
> I'm working on what is probably a complicated solution to a relatively trivial
> problem.  I have no idea whether I'm doing this right or not (well, obviously,
> I'm doing -something- wrong) but based on everything I've read, and all of the
> examples I could dig up, I don't see anything wrong with my structure.
>
> basically, I have a custom library:
>
> #ifndef _MY_LIB_
> #define _MY_LIB_
> #include <iostream>
> #include <cmath>
> using std::ostream;
>
> namespace geometry {
>
>     enum pointName{X,Y,Z};
>
>     class point3d
>     {
>         public:
>         .
>         .
>         .
>         friend ostream &operator <<(ostream &, const point3d &);
>
>         private:
>     };
>
>     class vector3d : public point3d
>     {
>         ...
>     };
>
>     const point3d ORIGIN;
>     const vector3d ZERO_VECTOR;
> }
>
> class implementations are handled in separate files, and compiled with:
>
> g++ -g -c -Wall -std=c++0x point3d.cpp vector3d.cpp
>
> This compiles fine, and everything is awesome until I try to use the << operator
> in my unit test program.  g++ gives me the following:
>
> g++ -g -Wall -o uTest unit_test.cpp point3d.o vector3d.o
> /tmp/cca86ida.o: In function `point_arithmetic_test()':
> /home/.../Documents/Projects/Planets/unit_test.cpp:56:
> undefined reference to `geometry::operator<<(std::basic_ostream<char,
> std::char_traits<char> >&, geometry::point3d const&)'
> /home/.../Documents/Projects/Planets/unit_test.cpp:57:
> undefined reference to `geometry::operator<<(std::basic_ostream<char,
> std::char_traits<char> >&, geometry::point3d const&)'
> collect2: ld returned 1 exit status
> make: *** [uTest] Error 1
>
> now unit_test.cpp, like both of my library files uses:

I forgot to type the #endif after the namespace in my example... It is there in
the real thing.
>
> using namespace geometry;
>
> if I remove the namespace wrapper from around my classes, everything works.
>
> can somebody tell me what I'm missing?
>
> Regards,
> A.D.B.

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