On Feb 13, 2004, at 4:11 PM, Andreas Raab wrote:

> Hi Guys,
>
> I have a question about dependency handling in Monticello. Here's what
> happened: I put the entire B3D enchilada up on SqueakSource all with 
> nice
> requirements stated. So, for example, I declared 
> Balloon3D-Morphic[-ar.2] to
> depend on Balloon3D-Kernel[-ar.2] which in turn depends on
> Balloon3D-Constants[-ar.2]
>
> Then, Bert factored out some parts of Balloon3D-Kernel and put them 
> into
> Balloon3D-Math, declaring an appropriate dependency between
> Balloon3D-Kernel[-bf.3] and Balloon3D-Math[-bf.1].
>
> However, trying to load Balloon3D-Morphic[-ar.2] still results in
> Balloon3D-Kernel[-ar.2] to be loaded. The question is: Is this 
> intentional
> or a bug? If it's intentional, is there a way to declare a "lazy 
> dependency"
> between packages which basically say "I don't care which version - 
> just the
> latest one"?!

It's intentional, but you may have uncovered a bug in the intent (I did 
*say* this dependency stuff was provisional, right?).  The use case I 
was picturing is that you would end up with one top level package 
("Balloon3D") that has (transitively) dependencies on all the rest.  
Then when you want to publish, you publish *only* the top level 
package.  It will recursively make sure that all of its required 
packages that have been modified (or that have required packages that 
have been modified - I need to check that it actually it does this) 
also get new versions published, which will have updated dependencies.  
So Bert would have published a new version of Balloon3D, which would 
have triggered a cascade of new versions of everything from Math on up. 
  Loading Balloon3D-Morphic-ar.2 would still get you 
Balloon3D-Kernel-ar.2, but there would now be a Balloon3D-Morphic-bf.3 
that depends on Balloon3D-Kernel-bf.3.

So that was the intent, but please poke holes in it.  The problem with 
doing "lazy" dependencies is it's never very clear what the "latest" 
version is, or how much tolerance to have (do you really want 
Balloon3D-Morphic-ar.2 to load Balloon-3D-Kernel-ar.765 some time in 
the future?).  And, generally, that feels like a release issue and 
should be handled by SM - if you're using dependencies in MC it's 
between parts of a package that you wholly control and so hard links 
*should* be manageable.  But there are clearly still some usability 
issues to work out.  In particular I don't know how to handle the case 
when you're only working with a subpackage and don't have the "whole 
enchilada" loaded...

Incidentally, the "modified" check is awful right now - it will only 
notice when you add or modify methods (and not add or modify classes, 
or remove anything, or recategorize, etc).  The 
SystemChangeNotification stuff should fix this.  Or maybe it should 
check the slow and sure way when publishing (as if MC wasn't slow 
enough already).  Anyway, you may need to add extra whitespace to 
methods or something to trick it into realizing that a dependency has 
been modified sometimes.

Avi