On Sun, Aug 31, 2008 at 9:12 AM, spaetz <[EMAIL PROTECTED]> wrote: > And second each added tag makes a) parsing slower b) the stylesheet more > unreadable (for maintainers).
Yeah - from the mapnik side of things we've already had Steve Chiltern asking for help. The filter rules become immense quite quickly. Lets imagine a basic line, that can be on a bridge or in a tunnel - so needs three filters foo = bar and tunnel = yes foo = bar and bridge = yes foo = bar but if there's now two ways of tagging the line, and maybe two ways to tag a tunnel/bridge, then the rules become unreadable: (foo = bar or (foo = ben and ben = neb)) and (tunnel = yes or (kol = lok and lok = web))) (foo = bar or (foo = ben and ben = neb)) and bridge = yes or (blah = ack and swe = ob)) (foo = bar or (foo = ben and ben = neb) ....and full of devious bugs like the eagle-eyed would notice in the rules above[1]. And the self same complexity then bubbles up all over the place (like in mkgmap, and the editors...) which simply continually raises the barrier to entry and therefore makes the osm dataset *less* useful, not more. I'm meeting up with Steve Chiltern next week to look at ways to make the style rules for mapnik more easily maintainable when we are both in Aberdeen, and if anyone is interested in helping please jump in and help. Cheers, Andy [1] the second line is missing some brackets, and matches all instances of the alternative bridge tagging, even those not on foo=bar lines). _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
