[mkgmap-dev] Style rules and 'generated' tags

Tue Jul 7 18:06:44 BST 2009

Hi

> And I think, if I would change the second line to
> 
> highway=* tag_a!=yes {set tag_b=yes}

adding in the missing '&' sign:
highway=* & tag_a!=yes {set tag_b=yes}

Then that is allowed, and the result would still be that all
highways were 0x01.

> it wouldn't change anything, or would it?

> What would happen, if the second lien would be changed to the following:
> tag_a!=yes {set tag_a=no; set tag_b=yes}

You cannot set the same tag that you are matching.  (Currently there is
a bug and it will hang, but the intended result would be just that it is ignored
as it is too late.)

All actions will be run before the final matching rule is selected and the
action rules are not run in any particular order.  So anything that relies
on the order of the action rules will not work reliably.

> So basically I am trying to use the action rules as a preprocessor for
> the OSM data.

So yes, could you think of what kind of preprocessing rules you want
and then we can either make the existing system do that or have a
separate pre-processing phase for that.

..Steve