On 15.06.2012 23:38, Peter Wendorff wrote: > To conclude: I really don't see any benefit in creating variable keys > over creating fixed keys with a variable, slightly more complex > (compared to the already complex one) value scheme.
There's one immediate problem: The 255 character limit for values. When you take the most complex example from http://wiki.openstreetmap.org/wiki/User:Imagic/Werkstatt2 and put it all into a single value like access:conditional = motor_vehicle:(Mo-Fr 16:00-18:00):forward no; agricultural:(Mo-Fr 16:00-18:00):forward yes; goods:(Mo-Fr 16:00-18:00):forward yes; motor_vehicle:(Mo-Fr 06:00-09:00):forward no; agricultural:(Mo-Fr 06:00-09:00):forward no; goods:(Mo-Fr 06:00-09:00):forward no then you already exceed the limit. You could change the syntax for that one a bit so it would still fit (e.g. omitting the ":00"), but I expect that there will be a few cases where 255 characters are definitely not enough. Other issues are: * While it's easier to _ignore_ one tag than several, we want mappers to be able to _edit_ them, and one tag will grow to "un-editable" size more quickly than multiple tags. * Key-based conditions are already being used. It would still be possible to define a value-based approach, though - with some kind of fallback if the value gets too long - and I agree that there are benefits for applications. So ultimately the issue with value-based approaches like the occasionally-suggested maxspeed:conditional = 80; [hgv][wet] 60 style or other similar variants is that nobody did get around to properly defining it yet. Tobias _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
