Where to place namespaces in c++ program

PLCnext Technology & PLCnext Controls
1

Hey everyone. Maybe I misread some of the documentation, but I cannot seem to find any info on how to write a c++ program for the PLCNext using additional libraries. In a “normal” programming environment, when I write a c++ program, I would simply make the #include at the top of the program.

Immediately below it, I would write the “using namespace” etc. for that library.
I am writing some software using the OpenCV library, which I have tested on a Windows machine, the code has a ‘normal’ lay-out, like this: #include “stdio”
#include “opencv/core/core.hpp” using namespace cv; int main (int argc, char** argv){ //Execution here } However, now that I am ready to use (re-write) this code for an AXCF2152, I can not simply use the “using namespace” syntax, because writing software for this target has to be done inside the library, example: namespace Library { namespace component {
program::program
{
// port info here
} void program::execute(){
//execution here
}
}} How do I go about using the namespaces from an imported library in an AXCF2152 program? I did not have any success adding them in the header file, or I made a mistake doing that… It would be greatly appreceated if anyone has some documentation or tips as to how this is done… Regards,
David.

2

Hi David, Using namespaces is exactly the same as in regular C++ (as it is regular C++). Given this class ‘Benchmark’ (cpp):

#include "Benchmark.h"
namespace NL_PXC {
namespace UTIL {

using namespace std::chrono;
}
}

for example the verbose way is would be

 NL_PXC::UTIL::Benchmark *bm;// = new Benchmark(5);

the more compact means would be:

#include "../util/Benchmark.h"


namespace NL_PXC { namespace Example_Database {

using namespace Arp;
using namespace Arp::Plc::Esm;
using namespace NL_PXC::UTIL;

class MyDatabaseProgram : public ProgramBase, private Loggable
{
public: // typedefs

public: // construction/destruction
    MyDatabaseProgram(const String& name);
    MyDatabaseProgram(const MyDatabaseProgram& arg) = delete;
    virtual ~MyDatabaseProgram(void) = default;

public: // operators
    MyDatabaseProgram&  operator=(const MyDatabaseProgram& arg) = delete;

public: // properties

public: // operations
    void    Execute(void)override;

private: // fields

   Benchmark *bm;// = new Benchmark(5);
3

That seems to work just dandy. Thank you. Regards,

David.