If you try to write to a GDML file, and that file already exists, a G4 application program will terminate with a fatal exception. For a simple example, go to examples/extended/persistency/gdml/G01. Build the example and execute: load_gdml axes.gdml axes-out.gdml It will execute without any problems. But if just hit an up-arrow and run the program again: G4GDML: Writing 'axes-out.gdml'... -------- EEEE ------- G4Exception-START -------- EEEE ------- *** G4Exception : InvalidSetup issued by : G4GDMLWrite::Write() File 'axes-out.gdml' already exists! *** Fatal Exception *** core dump *** **** Track information is not available at this moment **** Step information is not available at this moment -------- EEEE -------- G4Exception-END --------- EEEE ------- This makes testing any G4 application that can write a GDML file more difficult to test, since you always have to remember to delete the GDML output file. I tried to work around this in my application by deleting the GDML output file from my application if it existed: G4String gdmlOutput = \*whatever*\ G4FileUtilities utilities; if ( utilities.FileExists( gdmlOutput ) ) { auto result = utilities.DeleteFile ( gdmlOutput, "-f"); } G4cout << "Writing geometry to '" << gdmlOutput << "'" << G4endl; fGDMLparser.Write(gdmlOutput, fGDMLparser.GetWorldVolume()); But this does not work as intended. While the file 'gdmlOutput' is deleted, and the program appears to create the output file; e.g.,: Writing geometry to 'parsed.gdml' G4GDML: Writing 'parsed.gdml'... G4GDML: Writing definitions... G4GDML: Writing materials... G4GDML: Writing solids... G4GDML: Writing structure... G4GDML: Writing setup... G4GDML: Writing surfaces... G4GDML: Writing 'parsed.gdml' done ! the GDML output file is _not_ created. Why won't G4GDMLWrite::Write() overwrite an existing GDML file if that's what the user wants to do? And why, when I try the work-around above, is no actual GDML file created?
Thanks for pointing out this potential improvement. I have added a new method to the parser SetOutputFileOverwrite(G4bool flag) which allows you to set the flag to overwrite output files. To use it you will have to call: fGDMLparser.SetOutputFileOverwrite(true); fGDMLparser.Write(gdmlOutput, fGDMLparser.GetWorldVolume()); This functionality will be available in the next release of Geant4. As far as your work around is concerned, to be honest I don't know why it does not work... If you want to hack your current Geant4 installation to overwrite the file, you can edit G4GDMLWrite.cc file and comment out the lines 205-210 where the check for the file is done.
Modification will be available in the next coming release.
