Add {x+1} etc. tile simple math capabilities for URL templates

[jidanni]

Maybe like
​https://github.com/openstreetmap/iD/issues/6198
there should be the capability to say {x+1} etc. instead of just {x}.

[stoecker]

Actually I'd rather ask them if they can find and fix the error in their server. That does not look correct to me at all.

They probably copied the data with an off-by-one error.

[jidanni]

All I am saying is that one day one might be faced with such problems,
so there should be some flexibility in place in case it is needed.
Upstream might not be back in the office until Monday,
or their team might need a week to get their contractor to fix it...

​http://www.offline-maps.net/en/help/maps/stored/custom#custom_variables users
can deal with it out of the box, whereas JOSM users would be out of luck!
In fact it would be pretty hard to make some middleman function between JOSM and the Internet.

[stoecker]

There are many possibilities, but it makes no sense to implement each obscure system. I prefer to ignore strange stuff until there is a real need to support it. If everybody supports each bullshit there is no reason for the providers to follow any standards.

[jidanni]

Well all I can say is one day if a new standard came along, JOSM users would be helpless waiting for it to be approved by standards bodies, and then added to the list of fixed functions, whereas e.g.,
​http://www.offline-maps.net/en/help/maps/stored/custom#custom_variables
users could be up and running within minutes. All because their software had the ability to define "macros".

[stoecker]

If a new "standard" establish JOSM usually supports it as soon as it is used. But supporting broken servers is not our goal.

[jidanni]

One notices the site in question has a left window / right window slider. Though not actually the factor here, you never know why some sites might have shifted their tiles ... the site using such layers ​https://gis.swcb.gov.tw/ certainly has no such problem dealing with it, with the shift, and Google's layer, without the shift, at the same time. Reminds me of ​https://www.wikidata.org/wiki/Q29043602 . JOSM users would be locked out. Just what China wanted.