Request: Put default TTreePlayer::Scan parameters in config file

The function TTreePlayer::Scan has some default parameters that are hardcoded in the .cpp file.

Would there be any downside to moving the default values into the rootrc file so that it could be changed without recompiling? I know the text file has to be parsed when ROOT starts up, then internally the variable has to be retrieved instead of being baked into the source, but would it really have a significant effect given that it’s just Scan() after all? I hope no one is using Scan() and hoping for maximal performance…

For my own use I’d really like to change the default colsize parameter to be 12 digits to faithfully represent all possible integers (up to 64-bit, like timestamps) without resorting to scientific notation. I know I can just do “colsize=12” in the Option parameter, but I want it to be the default.

If we can’t move the parameters into rootrc, is it feasible to change the hardcoded default of 9 to 12? I guess some fragile text-parsing scripts could break, but I don’t see that as a huge problem.


Hi Jeff,

I see no downside in moving the hard-code setting from the source to the .rootrc except for the coding and testing time. If you get a chance to implement this change and a related test (and submit it via a pull request to our github clone), I will incorporate it.