The two tags needn't be a memory problem just by changing a few other things (I will post a patch within the next days). Anyhow we could decide to set mkgmap:closed=true and mkgmap:autoclosing=true only. I think mkgmap:closed might make sense to have a chance in the lines style to skip an element. I don't have a good example but there are some tags that can be used for lines and polygons.
Yes true, adding tags will often need no extra memory at all (when both the key and value have a limited set of values and are interned, which they are in this case), and sometimes a lot when the Tags hash map has to be resized. Adding fields as in my patch will always add a fixed amount of memory to each way. I don't know how it all balences out in a typical workload, but I think if you are going to add something to every way its probably best to just reserve the space for it.
Yes - and is_inpomplete() :-) At the moment I do not make good progress in the style-functions branch. Steve, do you think it's ok to merge the current implementation which requires that a function cannot be used on its own? Otherwise the optimizer removes the function-only-rule.
Yes, I think it is fine to merge in new features even if they are incomplete, as long as it doesn't affect the existing functionality.
P.S.: I am happy if you merge the style-include branch! Good work!
OK will do that later today. ..Steve