[ROOT] branching STL vectors directly

From: Troy D. Straszheim (troy@ifh.de)
Date: Thu Jun 10 2004 - 13:52:39 MEST 

Hi Talk,

I have an example here: branching a class, a typedef of a class, a
template class (containing a vector), and a typedef of a template
class containing a vector all work, but branching a vector directly
does not.  That is, the call

   tree->Branch("b", "MyTemplateClass<SomeOtherClass>", &somepointer);

works fine, but

   tree->Branch("b", "vector<SomeOtherClass>", &somepointer);

does not.  Am I overlooking something?

The example below should show the error with a simple

   % root -l test.C++

and the errors:

   % root -l test.C++
   root [0] 
   Processing test.C++...
   Info in <TUnixSystem::ACLiC>: creating shared library /home/troy/icetray/work/./test_C.so
   Error in <TTree::Bronch>: vector<XYZ> with no dictionary defined in branch: vectorofxyz
   Error in <TTree::Bronch>: vector<XYZ> with no dictionary defined in branch: vectorofxyz

This is with today's root from CVS on Linux 2.4.26 with gcc 3.3.2.

Any ideas would be greatly appreciated...

Best,

Troy Straszheim


============================================================

#include <TObject.h>
#include <TSystem.h>
#include <TTree.h>
#include <iostream>

#include <vector>
using namespace std;

struct XYZ 
{
  float x, y, z;
};

typedef XYZ XYZ_Typedef;

template <class T>
struct TemplateClass
{
  T array_of_t[15];
  vector<T> vector_of_t;
};

// explicit instantiations seem to make no difference
// template class TemplateClass<XYZ>;
// template class vector<XYZ>;

typedef TemplateClass<XYZ> TemplateClassXYZTypedef;

TTree *tree;

void test2() 
{
  tree = new TTree("T", "T");

  // branch a class: works
  XYZ *xyz_p = new XYZ;
  tree->Branch("XYZ", "XYZ", &xyz_p);
  tree->Fill(); 

  // branch a typedef of a class: works
  tree->Branch("XYZ_Typedef", "XYZ_Typedef", &xyz_p);
  tree->Fill(); 

  ////////////////////////////////////////

  TemplateClass<XYZ> *xyztemplate_p = new TemplateClass<XYZ>;

  // branch a template class: works, even when class contains a vector 
  tree->Branch("templateofxyz", "TemplateClass<XYZ>", &xyztemplate_p);
  tree->Fill();

  // branch a typedef of a template class: works
  tree->Branch("templateofxyztypedef", "TemplateClassXYZTypedef", &xyztemplate_p);
  tree->Fill();

  vector<XYZ> *xyzvec_p = new vector<XYZ>(100);

  //  doesn't work
  tree->Branch("vectorofxyz", "vector<XYZ>", &xyzvec_p);
  tree->Fill();

  //  also doesn't work, seemingly not a namespace issue
  tree->Branch("vectorofxyz", "std::vector<XYZ>", &xyzvec_p);
  tree->Fill();
  
}

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