TGPictureButton Not connected

Please read tips for efficient and successful posting and posting code

ROOT Version: Not Provided
Compiler: Not Provided


I am developing a ROOT GUI in a unique software environment for my experiment. I want to build a TGPictureButton for an event display which will allow navigation between events. I have a class called NavUtil which has functions Next() and Prev(). I have two images (basic arrows) which I want on the buttons and have attached these (no errors there, I think). I am now trying to connect the function to the buttons and I get this error:

FatalRootError: BEGIN
slot Prev() does not exist.

The button is connected in my code via this line in my top level main function (seperate file from :

b->Connect(“Clicked()”, “NavUtil”, util, "Prev());

where util is an object of type NavUtil. Prev is definitely a function within NavUtil and the header file for that NavUtil is included in this main file. Have I missed something?

Any help appreciated.
Thank You

You have to create a dictionary for your NavUtil class

Thank you for your response. Do you mean a seperate file with some sort of lookup table? I have a class.xml and class.h file which list all my classes already. These are just lists of classes. What other type of dictionary would I need?


You need the following:

Add this line at the end of your class definition (in the header file):

   ClassDef(NavUtil, 0)

Then you need a Lindef.h file containing the following lines:

#ifdef __CINT__

#pragma link off all globals;
#pragma link off all classes;
#pragma link off all functions;

#pragma link C++ class NavUtil+;


Then generate the dictionary for your class:

rootcint -f NavUtilDict.cxx -c NavUtil.h Linkdef.h

And add NavUtilDict.cxx in the list of source files of your project (in your makefile)

See also Interacting with Shared Libraries: rootcling


I figured the way to do this in our framework but I now have an issue with a “Warning: Unused class rule : EventDisplay::NavUtil”.

The class is defined within a .h and .xml file as is the case with our framework and I have included a ClassDef in my header files now:

class NavUtil : public TObject {
#ifndef CINT
explicit NavUtil();
#ifndef CINT
void PrevEvent();
virtual ~NavUtil(){}
ClassDef(NavUtil, 0);

Sorry, but I don’t understand what you’re trying to do with those #ifndef CINT… And did you generate a dictionary for your class?

No I don’t know how to generate the dictionary in the code framework. We use scons and so as far as I see in other files in our framework all you need to do is include these types of ifndef statements and the ClassDef with a statement “helper.classDef(True)” in the SConscript and genrelfex should take care of that…I am no expert, I could have completely missed the mark there…

I dont know which parts of the code should be between the #ifndef CINT#endif . I based this on a working example in our framework…it maybe wrong

So I’m afraid I can’t help there. You should ask someone who knows your framework and who could help

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.