[mkgmap-dev] if-then-else in style and style options

Wed Mar 8 08:54:29 GMT 2017

This is probably coming too late but I was going to suggest earlier that
the "end" directive be changed to "endif" to be more consistent with other
programming languages. I've been away from programming for a long time -
many languages (Java, C++, PHP) seem to use braces to end a control loop
nowadays. No big deal either way.

Also, in your example, would an "Else" directive before the "[0x1c
resolution 22]" the do the job? The program would still have to 'remember"
that it was evaluating the "if " statement above, however.

Dave

On Wed, Mar 8, 2017 at 3:34 PM, Gerd Petermann <
GPetermann_muenchen at hotmail.com> wrote:

> It would not work because 1=1 is interpreted as
> $1='1'
> and that will probably not be true.
> Same effect with '1' = '1' .
>
> Maybe we can add a style function "true()" which always retrurns true for
> this?
>
> Gerd
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Mittwoch, 8. März 2017 09:25:34
> An: mkgmap-dev at lists.mkgmap.org.uk
> Betreff: Re: [mkgmap-dev] if-then-else in style and style options
>
> Hi
>
> I think you should document that you need a dummy condition, ie
>
> if (...) then
>   1=1 {action}
>   ...
>   1=1 [0x1c ...]
> end
>
> (I assume this should work OK)
>
> Ticker
>
> On Wed, 2017-03-08 at 08:07 +0000, Gerd Petermann wrote:
> > Hi all,
> >
> > while writing the documentation I noticed this possible problem case:
> > The lines file in the default style contains these rules:
> > boundary=administrative { name '${mkgmap:boundary_name}' }
> > boundary=administrative & admin_level<3 [0x1e resolution 12]
> > boundary=administrative & admin_level<5 [0x1d resolution 19]
> > boundary=administrative & admin_level<7 [0x1c resolution 21]
> > boundary=administrative & admin_level<9 [0x1c resolution 22]
> > boundary=administrative [0x1c resolution 22]
> >
> > So, one may want to extract the clause boundary=administrative  like
> > this:
> > if (boundary=administrative) then
> >         { name '${mkgmap:boundary_name}' }
> >         admin_level<3 [0x1e resolution 12]
> >         admin_level<5 [0x1d resolution 19]
> >         admin_level<7 [0x1c resolution 21]
> >         admin_level<9 [0x1c resolution 22]
> >         [0x1c resolution 22]
> > end
> >
> > The problem: It doesn't work because the lines
> >         { name '${mkgmap:boundary_name}' }
> > and
> >         [0x1c resolution 22]
> > are not a valid rules and the rule parser "forgets" that the
> > boundary=administrative expression will be added.
> >
> > What do you think? Should mkgmap support this syntax?
> >
> > Gerd
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> > von Gerd Petermann <GPetermann_muenchen at hotmail.com>
> > Gesendet: Dienstag, 7. März 2017 20:10:52
> > An: Development list for mkgmap
> > Betreff: Re: [mkgmap-dev] if-then-else in style and style options
> >
> > Hi Andrzej,
> >
> > thanks, so I'll try to document the new syntax next.
> >
> > Gerd
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> > von Andrzej Popowski <popej at poczta.onet.pl>
> > Gesendet: Dienstag, 7. März 2017 17:40:16
> > An: mkgmap-dev at lists.mkgmap.org.uk
> > Betreff: Re: [mkgmap-dev] if-then-else in style and style options
> >
> > Hi Gerd,
> >
> > I have run some tests with current code and spotted no problems. I
> > have
> > tested both, if-then-else statement and style-option.
> >
> > --
> > Best regards,
> > Andrzej
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk
> > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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-- 
Dave Swarthout
Homer, Alaska
Chiang Mai, Thailand
Travel Blog at http://dswarthout.blogspot.com
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