About MC for managing the image

Andreas Raab andreas.raab at gmx.de
Sun Sep 18 20:29:57 UTC 2005


Hi -

Daniel Vainsencher wrote:
> However to me the fact that they specify a load order, instead of 
> loading all those versions simultaneously, looks like a bug. The way 
> I've been thinking about ordering issues is that if you need to specify 
> an order because of reference dependencies, that's what simultaneous 
> loading is for. If you need to specify an order for bootstrapping 
> reasons, then you should have a sequence of configurations that each 
> specify a step that works from the previous step, and allow those steps 
> to define the necessary orderings of changes.

Yes, you can do that. But what that means is more work since many 
implicit updates that work because of the implicit order will no longer 
work. This would be a net loss. Also, I do not understand what you guys 
refer to when you talk about "simultaneous" loading. What exactly does 
that mean? One of the advantages of packages is that you have control 
over granularity and that extends to loading them - the fact that you 
*can* specify the order in which packages get loaded is an advantage in 
my eyes (I certainly have used it often enough).

> So unless there's another reason for the total order, or a problem with 
> one of the above, it seems we can avoid specifying and maintaining a 
> load order, and also be able to load circularly dependent packages.

The need to "specify and maintain a load order" seems strikingly similar 
to "specify and maintain dependencies" ;-) But in any case, this is all 
about the cost-benefit ratio. As long as dependencies don't get into the 
way (so far they have) and offer actual advantages (so far they haven't) 
I'm all ears. Let's just not be too quick throwing the configurations 
out with the bath water - I'm not convinced yet that dependencies will 
offer any benefits over configurations; simply because I think having a 
well-defined (and accessible) load-order is vastly advantaguous to 
trying to figure out how to load what and deal with the effects when 
things go wrong. But we'll see and I'm certainly willing to give it a shot.

> So I'm proposing to have MCConfigs to use simu-load for users and 
> simu-merge developers, and ignore any specified order. Avi and have 
> sketched the needed changes out, I'll work on it soon.

Again, please explain "simu-load" and "simu-merge". This discussion is 
the first I ever heard about it and I just don't know what this means 
exactly.

But to summarize: Am I correct in understanding that you are proposing 
to change loading configs in order to use dependencies to create 
configurations? If not, I fail to see how this last paragraph relates to 
dependencies ;-)

Cheers,
   - Andreas



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