[OSM-talk] Proposed Relations

[Frederik Ramm]

Hi,

Shaun McDonald wrote:
> Relations are unordered. You could load the relation and all the ways 
> referenced by it, then check to see if each way has another way that has 
> the same start and end nodes, through a process of stitching.

1. Shaun is right BUT

2. I want relations to become ordered and will try to sneak this into 
API 0.6; there will be no noticeable change for any API client, just 
that it so happens that things are returned in the order you put them 
in, rather than in any order. The rationale behind that is that people 
start (ab)using the role attribute for that (e.g. a bus route with nodes 
that have the roles "stop1", "stop2", "stop3" etc.), which of course is 
a pain to modify.

3. No matter wheter API 0.6 will have ordered relations or not, I 
suggest to never rely on ordering in cases where it can be derived from 
the contents, i.e. if you have a border relation then by all means look 
at the first/last nodes of the ways and connect them rather than just 
assuming the elements are in the correct order.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"