[OSM-talk] [RFC] restriction=school_zone (second email)

[Roy Wallace]

On Fri, Aug 7, 2009 at 12:55 PM, John Smith<delta_foxtrot at yahoo.com> wrote:
> --- On Thu, 6/8/09, Roy Wallace <waldo000000 at gmail.com> wrote:
>
>> maxspeed[school_days][08:30-09:30]=40
>
> Except that is putting values on the key side of things. To do things properly you would need something like this.
>
> maxspeed:school_zone=40
> maxspeed:school_zone:on=08:30-09:30;14:30-15:30

Hmm I'm still undecided whether it really is necessary to enforce a
finite set of keys (i.e. force "putting values on the value side of
things"). But ok, if you think it is, my main point is still an issue:
perhaps we should explicitly state that the restriction applies on
"school days" rather than indirectly implying this by using
"school_zone".

And by the way, in the example you gave, you seem to be using
"school_zone" as a placeholder/ID, i.e. a means to link the two tags
together. Looking at things more generally what's really happening is:

maxspeed:foo=40
maxspeed:foo:on:day=school_days
maxspeed:foo:on:time=08:30-09:30;14:30-15:30

This is the problem with enforcing "values" (i.e. continuous values)
to be on the right hand side - you need a primary key to join tags.

To clarify my point further, how would you propose to tag a 50 kmph
maxspeed on Tuesday and Thursday afternoons, if you are forced to put
the "values" (i.e. Tuesday, Thursday, 50, 12:00-24:00) on the right
hand side?

Without that requirement, it's a one-liner:
maxspeed[Tu,Th][12:00-24:00] = 50