[mkgmap-dev] variable substitution in relation members

Mon Dec 21 19:20:01 GMT 2009

On Mon, Dec 21, 2009 at 12:08:26PM +0100, Clinton Gladstone wrote:
> Will logical comparisons also work with the variable substitution?
> That is, something like the following:
> 
> name != $(name:en) { ... }
> 
> This would make it easier to avoid redundant information in names.
> (Such as, in the example above, adding the English name only if it
> is not equal to the name.)

I understood the source code so that variable substitution would only
work in the right-hand-side of 'add', 'name', and 'set' rules.

I believe that the special name:* handling would be best implemented in
a special mkgmap option.  I would try to avoid writing language suffixes
in style files.  Styles can be globally useful, and the selection of
preferred language(s) is merely a parameter that should be passed to mkgmap
on the command line.  Perhaps something like this:

mkgmap --define name:LANG=name:en

> Earlier, i submitted a patch which introduced a not-equal filter which
> did this for me, but the patch was never committed: it would be great
> if there was a standard solution for this.

Would the not-equal filter be used something like this:

name '${name} (${name:LANG|ne:${name}}) | ${name}'

The ne: would be a not-equal filter, meaning that '${name} (${name:LANG})'
will be used when ${name} is not equal to ${name:LANG}.  I see value in this;
having a secondary language in parentheses could be useful in multilingual
areas or for foreign tourists.

Best regards,

	Marko