Command names with underscores must be invoked with dashes instead when upgrading from 6.7 to 7.0

Click 7.0 is breaking upstream packages, in our case mschematool (issue reported there: https://github.com/aartur/mschematool/issues/11).

After upgrading from 6.7 to 7.0, the init_db command can no longer be found.

$ mschematool xyz init_db
Usage: mschematool [OPTIONS] DBNICK COMMAND [ARGS]...
Try "mschematool --help" for help.

Error: No such command "init_db".
ERROR: Job failed: exit code 2

[davidism]

You can still use underscores by specifying the command names explicitly. It’s just that the default is now to replace with dashses, to look more consistent with other CLI tools, whereas before you would have had to specify those explicitly.

So if you want to upgrade your app to 7.0 but continue using the old names, you can name them explicitly, or use a Command subclass that doesn’t have the new behavior. There are upgrade strategies here, it just means Click 7.0 is not a drop-in upgrade in some cases.

[adityanatraj]

@davidism thanks for the commit ref and the explanation. I think it could have been more prominently described in the changelog (given python naming conventions would imply an insignificant number of people would hit this) but I do understand it was a major release. On our side, probably we should have pinned our dependencies better -_-.

perhaps it makes sense to attempt both for some interim period? of course, you’d have to dedupe (and raise some exception) when someone goes wild and attempts to register both styles…

@di nice to see you!