[augeas-devel] Re: [config-model-users] Semantic problem in augeas sshd lens ?

[Dominique Dumont]

David Lutterkort <dlutter at redhat.com> writes:

>> Understood. The problem I face is to save the content of a
>> config-model tree into an augeas tree. config-model model has the
>> notion of list but does not distinguish between a "seq-like" list and
>> a "multiple node" like list. 
>> 
>> Is there a way to query Augeas at run-time what kind of list it wants ?
>
> Are you trying to completely drive Config::Model off of metadata ? I
> think you'll always need some knowledge about the way a specific file
> format is mapped into the tree. How are you planning on generating UI if
> it's based solely on metadata ?

I've indeed thought about generating a UI from Augeas lenses but too
many informations are missing from Augeas lenses to provide a usable
GUI.

On the other hand, the current way of reading and writing through
Augeas is completely generic. The structure of Config::Model model is
used to generate Augeas "set" command. But, from what I've understood
of lenses, a Config::Model list can be represented in Augeas as a
"seq-like" list or a "multiple node" like list. Theses 2 lists have
different syntaxes in Augeas set command: "foo/0/" and "foo[0]". 

So I need to resolve this ambiguity when writing Config::Model lists
into Augeas.

> In any event, there's no runtime support right now to introspect the
> tree schema - it would be fairly easy to generate something like
> Relax-NG that describes the tree structure from lens definitions. Would
> that help you ?

I'd rather have a small call to Augeas to get some more informations
out of some Augeas nodes.

Aynway, I need to dig more the lenses doc to better understand the
differences between the "seq-like" list and the "multiple node" like
list and their intented purpose.

All the best

-- 
Dominique Dumont 
"Delivering successful solutions requires giving people what they
need, not what they want." Kurt Bittner