extended attribute standardization

[Claes at work]

On 11/19/06, Vegard Nossum <vegard at peltkore.net> wrote:
> What I would like to discuss and later put in writing are actually rather
> simple things. I think, for instance, that it would be useful to store
> arrays of information in extended attributes (think of a file history of
> source URIs whenever a file is copied or moved). Storing an array would
> require some kind of encoding where each element is separated by
> semicolons. Now there must be a way of storing semicolons in the elements
> themselves, so there must be an escape sequence for semicolons. This is
> not a very complicated concept in itself, but different people come up
> with different solutions (which may or may not be equally good). I think
> that discussing these things and writing them down will benefit
> programmers in the future.

Freedesktop hosts a page called Standards/shared-filemetadata-spec
which defines datatypes, where one type is "Array of String (comma
delimited list of strings)". As far as I understand it, this spec
mainly deals with metadata that is indexed in external systems, but it
makes sense to borrow from this spec for example the datatypes. Some
escape mechanism should probably be added to deal with strings that
includes commas.

I also noted that the desktop entry spec sometimes refers to lists,
but does not always  define the separator. For example for the keys
OnlyShowIn, NotShowIn, FilePattern.

Claes