Nikita Karetnikov <[email protected]> skribis: >> It actually does, but it has no side effect. > > I know that printing is a side effect. Why do you recommend to use > 'alist-cons'? If it's not possible to display anything, then > 'roll-back' won't be able to print the following messages.
It’s just the /option handler/ (the procedure passed to SRFI-37 ‘option’) that should not print anything. It is then OK to print things, of course, like is done for other options. Check how the other options are handled: during ‘args-fold’, the option handler just adds to RESULT an element saying that this option was passed. Once ‘args-fold’ has completed, we check its result: if it contains a pair whose key is ‘install’, then it means we want to install something, and so on. >> When ‘--profile’ is passed, the result of ‘parse-options’ contains a >> pair whose key is ‘profile’. The (assoc-ref opts 'profile) calls that >> you see retrieve the argument given to ‘--profile’. > > It's clear. But where should I call (assoc-ref opts 'profile)? Should > I do it in 'process-query'? In ‘process-actions’ more precisely, because roll-back is an action, not a query. And ‘process-actions’ already does that. HTH, Ludo’.
