Hello,
It appears the hadd utility does not support merging THStacks. Does that sound correct? Would the ROOT development community be interested in a patch to add support, were I to write one?
Thanks,
Matthew Lockner
Hi Matt,
Of course you are welcome to implement this improvement. 
Let us know if you make progress.
Rene
Hello Rene,
Patch is attached as patch_hadd.cxx (the board wouldn’t allow the .patch extension…). It is a diff against a trunk copy, updated this afternoon. Working fine for what I needed it for, but feel free to let me know if a bug is found down the road.
Enjoy,
M. Lockner
patch_hadd.cxx (1.69 KB)
Hi Matt,
Great! and well done.
Your patch is now in SVN.
I will include the corresponding changes in TFileMerger too.
Rene