C++ namespace question

[Veritas]

OK, I am finally forcing myself to start implementing namespaces in my projects. I have a question as how to make the following a little more elegent:

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BOOL GL_Window::Initialize ()
{
                ...
   {
   using namespace glGraph;
   g_graph = new CglGraph();
   }
                ...
}


I try doing:

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 g_graph = new glGraph::CglGraph();

But that causes compiler errors. Any clues?

[just brew it!]

What sort of errors are you getting? The following test program compiles and runs just fine, both under Visual C++ and g++.

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#include <stdio.h>

namespace ns1
{
    class c1
    {
    public:
        c1() { printf("c1()\n"); };
        ~c1() { printf("~c1()\n"); };
    };
    typedef c1 *c1ptr;
};

int main(int argc, char* argv[])
{
    printf("enter main()\n");
    ns1::c1ptr p;
    {
        p = new ns1::c1();
        delete p;
    }
    printf("exit main()\n");
   return 0;
}


Edit: Another version, probably closer to what you are doing (one namespace invoking another):

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#include <stdio.h>

namespace ns1
{
    class c1
    {
    public:
        c1() { printf("c1()\n"); };
        ~c1() { printf("~c1()\n"); };
    };
    typedef c1 *c1ptr;
};

namespace ns2
{
    class c2
    {
    public:
        c2() { printf("c2()\n"); };
        ~c2() { printf("~c2()\n"); };
        void Initialize();
        ns1::c1ptr p1;
    };
    typedef c2 *c2ptr;
};


void ns2::c2::Initialize()
{
    printf("c2::Initialize()\n");
    p1 = new ns1::c1();
    delete p1;
}


int main(int argc, char* argv[])
{
    printf("enter main()\n");
    ns2::c2ptr p2;
    {
        p2 = new ns2::c2();
        p2->Initialize();
        delete p2;
    }
    printf("exit main()\n");
   return 0;
}


[Buub]

But that causes compiler errors

What compiler? Looks like it doesn't properly implement current C++ standards.

[Veritas]

I am using g++ 3.2 (really mingw -- which is gcc for windows)

[just brew it!]

I am still unsure of what your problem is. How does your code differ structurally from the example I posted above? And what error message are you getting?

Edit: FWIW, I used g++ 3.2 to compile my test code.

[pez-king]

I see no reason there should be an error unless your compiler isnt working happy.

Try a different compiler maybe

[Craig P.]

If you can produce a stripped-down example that still doesn't compile, the online compiler at http://www.comeaucomputing.com is a good sanity check. It's generally considered to be the most standard-conforming in existence, and there are only a few corner cases where there's any dispute as to whether it does the right thing.

[Buub]

Oh by the way, the correct C++ standard variable to use is "bool", not the old MS macro "BOOL". :-)

[Craig P.]

Oh by the way, the correct C++ standard variable to use is "bool", not the old MS macro "BOOL".

Not if you're working with Windows headers or frameworks based on that (notably MFC, ATL and WTL may do it too).

In general, I would expect BOOL to be an integer typedef taking values TRUE and FALSE, but I think with Windows you sometimes get other values too. This is perfectly standard C++, if not necessarily the optimum way of doing it.

[Veritas]

Oddly enough, it works fine doing this now as follows:

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BOOL GL_Window::Initialize ()
{
                ...
   g_graph = new glGraph::CglGraph();
                   ...
}


I did not change a thing...there must be a problem with VC++6.0 ;^)

[Craig P.]

there must be a problem with VC++6.0 ;^)

Now that's the understatement of the year.


(said somewhat for effect -- it's got holes, but it's still not that bad)