[OSM-talk] Users, contributors and developers
80n
80n80n at gmail.com
Fri Apr 27 12:04:04 BST 2007
On 4/27/07, Frederik Ramm <frederik at remote.org> wrote:
>
> Hi,
>
> > Am I missing something here, if we allow the key column to take any
> > format
> > of tags separated by colons and the value column separated by
> > semicolons do
> > we not get all the flexibility we need without introducing unnecessary
> > restriction?
>
> As far as I understood, many people called for the "third column"
> because they were hoping to get rid of the colons. The colons are a
> pain to process in environments where you do not routinely have
> string operations available, e.g. XSLT transformations.
I've not found the colons to be problematic at all in XSL transformations.
XSL has a reasonable set of string functions and most things can be done if
you know how.
It is tru that many things that are simple in other languages appear
non-trivial in XSL unless you understand the correct approach. Programmers
are generally at a disadvantage until they "un-learn" the procedural way of
doing things.
The same, even more so, goes for semicolons in values; you do not
> want to have to check values for semicolons every time you use them.
> If you need a list of things, it is far, far better to somehow find a
> way to tell the database that here is a list of things, than trying
> to encapsulate the list in a string field.
>
> Extrapolating your argument into a nice little strawman, one could
> say "why do we even have keys, let us just put one big text field for
> each way, where people can then write something like
> 'highway=residential,name=Brauer Blvd.,...'". Such a scheme would
> offer maximum flexiblity; one could even use that string to enter
> groupings like the one asked for by Spaetz ("highway=residential,
> (restriction=oneway,restriction_valid=8am-8pm),
> (restriction=noaccess...)"). But it would be a nightmare to work with
> that in a renderer or an editor.
>
> Bye
> Frederik
>
> --
> Frederik Ramm ## eMail frederik at remote.org ## N49°00.09' E008°23.33'
>
>
>
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