When we introduced tab completion in bug 7867, we noticed that some scripts printed errors and warnings on the commandline while tabcompleting, see example from tlctl below. > tlctl session list <tab>tlctl: error: could not retrieve data from the master: Permission denied > tlctl: error: could not retrieve data from the master: Permission denied Our current architecture in tlctl has no flexibility to consider what features the caller is interested in, and the caller has no way of controlling its call to get these special features. In practice, we have run into this issue when wanting to silence errors during tab completions. In tlctl, it is currently solved is by temporarily redirect stderr. However, it would be better to move more control into the hands of the caller. The same issue is seen in hivetool, where warnings.warn() is used to be able to silence errors during tab completion. Despite solving the issue in different ways, I believe a solution to this bug could be applicable to both scripts.
