Singleton pattern

Surpose the Routing Graph is used everywhere in the code, but it should only be initialized once(by calling its init_from_psf() method).

A clean solution is to use singleton pattern. Declare an instance() mehtod, which is static. In the instance() method, a flag is set to ensure only the flag has a value of zero, the method init_from_psf() will be called.


#include ".\routinggraphsingleton.h"
#include

RoutingGraphSingleton::RoutingGraphSingleton()
{
}

Routing_Graph* RoutingGraphSingleton::instance() {
if (_instance == 0) {
_instance = new Routing_Graph;
cout << "Loading routing graph... "; _instance->init_from_psf();
cout << "Done." << endl;
}
return _instance;
}

Routing_Graph* RoutingGraphSingleton::_instance =0;

---------------------------------------------------------------------------
header:

#include "routing_graph.h"

using namespace lb_dp_routing;

class RoutingGraphSingleton
{
public:
static Routing_Graph* instance();
protected:
RoutingGraphSingleton();
private:
static Routing_Graph* _instance;
};

NLS_LANG

After the new PL/SQL developer is installed, there is an error dialog "Database character set and client character set are different".

Because when my Oracle was installed, the character set parameter was set to UTF. Now the PL/SQL developer gets the NLS_LANG from system, which has a value of "GERMAN_GERMANY.WE8MSWIN1252". So this conflicts with the database setting and could cause data loss problem.

Solution: create NLS_LANG parameter in Enviroment Variables, set its value "American_America.AL32UTF8".