[mkgmap-dev] Syntax Question

Fri Jun 17 12:05:39 BST 2011

Hi

> railway=rail&  !(tunnel=yes)
>
> railway=rail&  tunnel!=yes

In this particular case they are the same.

I would normally prefer the second as being more readable, but something 
like:

   !(red=yes | green=yes | blue=yes)

may be easier to read than the equivalent:

    red!=yes & green!=yes & blue!=yes

In other cases however you have to consider if the tag exists. So
although
	speed<30
and
	!(speed>=30)
are logically the same, this is only the case if the speed tag
exists (and is a number).

So if there is no speed tag, both '<' and '>=' would give false
against any number and so
	speed<30 is false
and
	speed>=30 is false
and so
	!(speed>=30) is true

..Steve