Hi Konrad, Konrad Hinsen <konrad.hin...@fastmail.net> skribis:
> On 16/12/2019 23:09, Ludovic Courtès wrote: >> So in a more algorithmic manner: >>> 1. if ad-hoc and inputs-of is present at the same invocation: fail >>> hard. (With an error like incompatible options present) >>> 2. if only ad-hoc is present, then print a deprecation warning (yes, >>> we could make this suspendable with an environment variable, like you >>> described) >>> 3. if only inputs-of present, then do the new behaviour. >>> 4. if neither ad-hoc nor inputs-of present then >>> a. if GUIX_ENVIRONMENT_DEPRECATED is 1: do the current behaviour, >>> b. if GUIX_ENVIRONMENT_DEPRECATED is undefined, or is not 1: do the >>> new behaviour. >> That sounds like a good plan to me. >> >> #4 is the trickiest, and I think it’d be good to give users a bit of >> time so they can start adjusting before deprecation is in effect. > > #4 is trickiest for another reason: there is no future-proof use of > "guix environment" that works right now and will continue to work. Nor > is there any way to see, when looking at a command line, whether it's > old-style or new-style, if neither --ad-hoc nor --inputs-of are > present. This means that all existing documentation (tutorials etc.) > will become misleading in the future. Worse, even documentation > written today, in full awareness of a coming change, can't do better > than saying "watch out, this will do something else in the future". > > The first rule of backwards-compatibility is: never change the meaning > of an existing valid command/API. Add new valid syntax, deprecate old > valid syntax, but don't change the meaning of something that was and > will be valid. Yeah. Clearly there’s a tension between that and keeping Guix open to changes. > How about a more drastic measure: deprecate "guix environment" and > introduce a new subcommand with the desired new behaviour? That has the advantage of avoiding the problem you mention altogether while also allowing for further changes. The hard question then becomes: what do we call it? I vote against abbreviations. :-) Also, what other goals would we set for that command? How would we frame it in the set of commands? Thanks, Ludo’.