Templated member functions in root.

From: Brett Viren <bv_at_bnl.gov>
Date: Tue, 15 Feb 2005 18:50:08 -0500

Hi,

I have a class that has a few templated member functions that don't seem work in interpreted code. The full code can be browsed here:

http://minos.phy.bnl.gov/~bviren/minos/software/hm/HistMan/

This is a helper class that provides a simple histogram manager. It all works well in compiled code and non-templated methods work in interprete code, but templated methods don't. The actual implementation is a manually compiled library (not ACLiC) that is gSystem->Load()ed into a root session.

The meat of the problem can be seen by looking at the Book<>() method which is templated in order to assure type safety.

class HistMan {
public:
...

    /// Book 1D or 2D histograms of type THType.  Return pointer to created
    /// histogram (HistMan retains ownership) or 0 if "path/name"
    /// conflicts with previously existing histogram.

    template<class THType>
    THType* Book(const char* name, const char* title,

                 int nbinsx, Axis_t xmin, Axis_t xmax,
                 const char* path=".") {
        TH1* h = Adopt(path, new THType(name,title,nbinsx,xmin,xmax));
        return dynamic_cast<THType*>(h);

    }
...

};

This is supposed to be used like:

  HistMan hm("path");
  TH1D* h = hm.Get<TH1D>("h","hist",100,0,10);

but which produces the following in root:

---

root [0] gSystem->Load("libHistMan")
(int)0

root [1] HistMan hm("foo")
root [2] TH1D* h = hm.Book<TH1D>("h","hist",100,0,10); Error: Symbol hm is not defined in current scope FILE:(tmpfile) LINE:1 Error: Failed to evaluate hm.BookError: Symbol TH1D is not defined in current scope FILE:(tmpfile) LINE:1 *** Interpreter error recovered ***
root [3] hm
(class HistMan)150525008

root [4] hm.BaseFolder()
(class TFolder)150648744

---

Note that the object itself and non-templated methods (this one returns a reference to the underlying folder holding the histograms) work as well.

So, my question is: should this be expected to work, and if so what might I be doing wrong.

ROOT 4.01/05, GCC 3.3.5 x86 Debian.

Thanks,
-Brett. Received on Wed Feb 16 2005 - 00:50:24 MET