[augeas-devel] Re: New example at creating a lens

[Jeff Johnson]

On Jul 15, 2009, at 1:31 PM, David Lutterkort wrote:

> On Wed, 2009-07-15 at 16:21 +0200, Free Ekanayaka wrote:
>> The point is probably that even if the lens gets merged upstream,  
>> that
>> doesn't make much difference.
>
> It's at least the right answer to the question of lens versioning -  
> that
> way you can be sure that you always have the lens that matches the
> version of your daemon. And as Raphael said, maintaining the lens
> together with the distro package is a good first step to pushing the
> lens upstream.
>

Lens versioning will morph to automagic dependency extraction
duplicated into packages in a flash. Been there, done that,
many times.

>> If we allow other packages to modify the
>> configuration file provided by some package, that package has to
>> ensure that upgrades happen smoothly and that the semantics of the
>> modification is preserved.
>
> There's actually two separate issues: (1) package A needs to modify a
> config file that belongs to package B (e.g., add an entry
> to /etc/services) Whether that is appropriate depends on what exactly
> the file modification is. The expectation is that package B provides
> appropriate lenses for its config files. (2) package X makes
> backward-incompatible changes to its config file in an update. Augeas
> can help with moving old config files forward assuming there are  
> lenses
> for both the old and the new format.
>

There's more to the lens packaging problem (in RPM) than having A
	Require: B
because of dependency loops leading to indeterminate ordering.

73 de Jeff