On 01.09.2015 23:22, Nathaniel Smith wrote:
What makes it particularly difficult is that if you "fix a bug" in a library like appdirs, so that it starts suddenly returning different results on some computer somewhere, then what it looks like to the end user is that their data/settings/whatever have suddenly evaporated and whatever disk space was being used for caches never gets cleaned up and so forth. Generally when applications change how they compute these directories, they also include tricky migration logic to check both the old and new names, move stuff over if needed, but I'm not sure how a low-level library like this can support that usefully...
A low-level library could provide an API to return "legacy" directories. These could on Freedesktop-compliant systems for example be the fallback directories which are used when the environment-variables are not present. And after bugfixes (see what Nick said), the old, incorrect behaviour could be presented. An application could, after not finding its data in the non-legacy directories, query the legacy directories and start a migration process. regards, jwi