impossible to use type-erased write API to write an existing object

[eguiraud]

I would like to write (something equivalent to) the following:

auto m = RNTupleModel::Create();
auto field = RFieldBase::Create("v", "ROOT::VecOps::RVec<int>").Unwrap();
ROOT::RVec<int> rvec = {1, 2, 3};
m->AddField(std::move(field), (void*)&rvec);
auto w = RNTupleWriter::Recreate(std::move(m), "r", "somefile.root");

but that RNTupleModel::AddField signature is missing and I could not find another way to do this correctly.
For example the following example code adds a single field to the model ("v") but it adds two corresponding RFieldValues to model->GetDefaultEntry(), one explicitly with m->GetDefaultEntry()->CaptureValue() and one implicitly with the m->AddField(std::move(field)) call.

   // write out RVec
   {
      auto m = RNTupleModel::Create();
      auto field = RFieldBase::Create("v", "ROOT::VecOps::RVec<int>").Unwrap();
      ROOT::RVec<int> rvec = {1, 2, 3};
      m->GetDefaultEntry()->CaptureValue(field->CaptureValue(&rvec));
      m->AddField(std::move(field));

      auto w = RNTupleWriter::Recreate(std::move(m), "r", fileGuard.GetPath());
      w->Fill();
      rvec.clear();
      rvec.push_back(42);
      w->Fill();
   }

[jblomer]

Remember to fix-up the rfield_vector.cxx unit test once this has been addressed.

[github-actions]

Hi @jalopezg-r00t, @jblomer,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖