After a long discussion on IRC (mostly between Michael and me) two views on how general flags should behave have emerged. Since Michael and me is of different opinions we would like some more input on this topic.
Currently we have three levels of use flags, were each lower level override an higher level: dist use flags (Data/DistUseFlags.conf), system use flags (Settings/UseFlags.conf) and one off flags (USE="", mostly for debugging). Flags are set by +foo and reset by -foo. A flag can be set (on) or not set (off). There exists no state where the flag is set to "off", it just isn't set when off. For generic flags, they try to select the best available flag in a group of flags. If we for example have "aaa: bbb ccc ddd", where "aaa" is a generic flag and "bbb", "ccc" and "ddd" are specific flags, +bbb is set if available in the recipe, else +ccc is selected if available, else +ddd is set if available (and so on if the group is bigger) when +aaa is set. But if any specific flag is set that overrides the group selection in the generic flag, that is if +ccc is set by the user this will override the group and will be used in the example above instead of best available. This is so the user can select a specific implementation. Generic flags are applied after all user specified use flags, so that any generic flag set by the user will be taken into account when generic flags are parsed. Now, I'd like that generic flags do not enable flags I've reset, or more specifically turned off. If the flags available is the same as above and I have "+aaa -bbb" I'd like that "bbb" is not set when generic flags are parsed, instead "ccc" or "ddd" should be used. This requires a state that remembers that I've reset the state for when generic flags are parsed. At the moment -bbb just resets the "bbb" flag (unsets it) and +aaa enables the generic flags which will select from the "bbb ccc ddd" group, but I think that specifying -bbb would remove "bbb" from the selection group, so that the best from "ccc ddd" is set by the generic flag instead. A problem with this approach is that there's no way to reset a generic flag to the default behaviour. If +bbb is set there is no way to reset "aaa" to selecting from the full "bbb ccc ddd" group. Currently just specifying -bbb resets that flag and "aaa" will return to default behaviour but with "my" implementation specifying -bbb will remove "bbb" from the selection group. A solution to this would be that specifying +aaa in any level would reset the "aaa" behavioiur and would quench any specific flags set in earlier levels. So having "+aaa +bbb +aaa" would give normal behavioiur for "aaa". A problem with this solution is what will happen if a specific flag is present in multiple generic flags (for example the specific flag "qt3" is part of both "qt" and "gui" generic flags). Say that we, in addition to the above generic set, have "iii: bbb jjj kkk", what will be the effect of "+foo -bbb +iii"? Will +foo set +ccc (as "bbb" is removed from the selection) and +iii set +bbb (as +iii was specified after "bbb" was removed with -bbb)? The result thus being "+ccc +bbb", which means that from the "aaa" selection set two flags will be set and is this a problem? A solution to this is to not allow specific flags to be present in multiple generic flags. Hope to get some input on this and in the end come to a consensus. -- /Jonas _______________________________________________ gobolinux-devel mailing list gobolinux-devel@lists.gobolinux.org http://lists.gobolinux.org/mailman/listinfo/gobolinux-devel
