Callback function in TTree->Draw("someVar", "callBack(som

Hi All

I have a root script which I compile before execution. It contains the function:

float callBack(int somevar, int anothervar)
{
....
   return someFloat;
}

At some point, I would like to use this function as a callBack for the selection of what to draw:

myttree->Draw(“someVariable”, “weight*callBack(var2, var3)”);

Unfortunately, this doesn’t work. There is no error, but the function is never executed (checked with a debug message inside the function) and the statement is just ignored.

Do I need to register the callBack function in ROOT somehow beforehand? Or do the callback function inside the Draw command only work with interpreted scripts? Any help is appreciated.

ctopfel

Correction:

The function obviously is called, but std::cout doesn’t work. So please ignore this thread :slight_smile: