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[mkgmap-dev] Syntax Question

From Steve Ratcliffe steve at parabola.me.uk on Fri Jun 17 12:05:39 BST 2011


> 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 

   !(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
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
	speed>=30 is false
and so
	!(speed>=30) is true


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