ROOT6: Load library and create object in same macro

ROOT
#1

Hi,

I am trying to load a library (with gSystem->Load()) and then create an object of a class from that library in the same macro. It does not work; I am getting linker errors.

The problem is described here: indico.cern.ch/event/279723/ses … ides/1.pdf (slide 4)

The workaround described there works (load in load.C, create object in useClass.C, and run these macros from run.C). However, the slide says that this has been fixed.

I am confused. I am using CMSSW_7_5_0_pre1 with ROOT 6.02/05.

Does anyone know how to make this work from the same macro? The workaround is sort of cumbersome, especially if you have many macros.

Thanks!
Peter

#2

Hi Peter,

for v6.02 you have two options: create a rootmap file for the library to be loaded or use the following construct:

namespace {
  int loadMyLibraryTriggerFunc() {
    gSystem->Load("myLibrary");
    return 0;
  }
  int loadMyLibraryTrigger = loadMyLibraryTriggerFunc();
}

in the global scope (i.e. not inside a function).

In the master (future 6.04) we have improved this considerably; there you can just put R__LOAD_LIBRARY(myLibrary) somewhere next to the #includes.

Cheers, Axel.

#3

Works perfectly. Thanks!