[Distutils] Buildout: caching of base configuration ('extends')

[Jim Fulton]

On May 27, 2009, at 8:56 AM, Thomas Lotze wrote:

> Hi,
>
> I've been implementing a download API for buildout and have reached  
> the
> point where I'd like to try using it for downloading the base config  
> files
> referenced from a buildout config by the 'extends' option. This  
> would have
> the benefit of allowing to cache those config files and being able  
> to run
> a buildout using that feature while being offline.
>
> However, I'd like to discuss two points about doing this:
>
> - I think buildout should not unconditionally use a cached copy of a  
> base
>  configuration file. While it is sensible in other use cases to never
>  access the network if a file is found in the cache, base configs can
>  be expected to change and should IMHO be taken from the cache only  
> when
>  offline mode is active or an attempt at downloading failed.

Absolutely.


> - The download cache to be used is configured as one of the options  
> that
>  are read from either ~/.buildout/default.cfg or buildout.cfg and  
> their
>  respective bases. In order to keep things simple, I'd suggest to  
> use a
>  download cache only if specified directly inside any of these two  
> files,
>  and ignore download-cache options in any downloaded base configs.  
> This
>  would be an exception to how options read from config files are
>  combined, but one I deem worthwhile.

-1 on allowing the settings in only these 2 files.

>  I'd allow for configuring and using different download caches in  
> those
>  two files, though. That way, bases of the user's default config can  
> be
>  cached centrally while allowing to keep project-related stuff in a
>  different place.
>
> Opinions?

The solution seems too complicated to me. Too many special rules.

Maybe there should be a separate settinf for this, like extends-cache  
or something.

Jim

--
Jim Fulton
Zope Corporation