3.1. SpecTclDB::CDatabase

This section will introduce the CDatabase class through a set of simple examples. These examples include code fragments that:

1. Create and attach a database.

2. Create and lookup a save set.

3. List the savesets that are already known to a database.

These examples and a sample Makefile built along the lines described below are installed in the share/dbexamples directory of SpecTcl's installation directory tree.

If you intend to do serious programming with this class library, you should study the reference material in the appendix.

Before we can write any code, we need to be able to link compile and link our programs to this library. This requires a set of compilation and link flags. In both cases below, in order to factor out the distribution directory for SpecTcl, we'll assume that the environment variable SPECTCLHOME is defined to be the top level directory of the SpecTcl installation you are using. Note that environment variables are imported to Makefiles as Makefile variables (e.g. $(SPECTCLHOME) is the environment variable SPECTCLHOME). SpecTcl depends on Root so we're also going to assume that ROOTSYS is defined and points to the directory from wich SpecTcl was linked with root. As of version 5.3-007, the $SPECTCLHOME/VERSION file will tell you the value used for ROOTSYS.

A final note. If root was not built with internal -rpath's turned on the sample program in this manual (and even SpecTcl itself) may fail with an error like

./makedb: error while loading shared libraries: libvdt.so: cannot open shared object file: No such file or directory If that is the case then set up the full Root environment by $ROOTSYS/bin/thisroot.sh

Let's look at the simplest example. A complete program that creates an empty database. The program takes a databsae filename on the command line as a single argument.

#include <SpecTclDatabase.h>               
#include <iostream>
#include <stdlib.h>

int main(int argc, char** argv)
{
  if (argc != 2) {
    std::cerr << "Usage: makedb db-filenme\n";
    exit(EXIT_FAILURE);
  }

  SpecTclDB::CDatabase::create(argv[1]);          

  exit(EXIT_SUCCESS);
}

                

Let's look at another simple full program. This program will open an existing database and create a saveset named a saveset in the database. The program will also demonstrate very simple error detection.

#include <SpecTclDatabase.h>
#include <SaveSet.h>                
#include <iostream>
#include <stdexcept>
#include <stdlib.h>


int main(int argc, char** argv)
{
  if (argc != 2) {
    std::cerr << "Usage: makesaveset database-name\n";
    exit(EXIT_FAILURE);
  }
  try {
    SpecTclDB::CDatabase db(argv[1]);     

    SpecTclDB::SaveSet* pSaveset = db.createSaveSet("a saveset"); 
    delete pSaveset;
  }
  catch (std::exception& e) {
    std::cerr << "Error: " << e.what() << std::endl; 
    exit(EXIT_FAILURE);
  }
  exit(EXIT_SUCCESS);

}

                

As an excersise, modify this program to accepts, as a second parameter, the name of the save set to create. In the next, and last example in this section, we'll list the names of all of the savesets in a database.

#include <SpecTclDatabase.h>
#include <SaveSet.h>
#include <iostream>
#include <stdexcept>
#include <stdlib.h>


int main(int argc, char** argv)
{
  if (argc != 2) {
    std::cerr << "Usage: lssaveset db-filename\n";
    exit(EXIT_FAILURE);
  }
  SpecTclDB::CDatabase db(argv[1]);
  auto savesets = db.getAllSaveSets();                 
  std::cout << " Save sets in " << argv[1] << std::endl; 
  for (int i =0; i < savesets.size(); i++) {
    std::cout << savesets[i]->getInfo().s_name << std::endl; 
    delete savesets[i];                                  
  }
}