Hi all

I am proposing to add a package make variable.  The reasons are as follows:

"update" target is a great thing in our package system.  I think it is a big
advantage over the FreeBSD port system.  However, sometimes, when I do "make
update", it triggers updates of a lot of other dependent packages.  For
example, "make update" for libaudiofile makes my machine update Gnome, KDE
and many other big packages that use them, some of them I just updated before
I update libaudiofile.  I do want to get them all updated, but this
repeating wastes a lot of time.  

So, I think it would be a time saver if we can have something that indicates
the depth of a package in the package dependency tree.  We can have a variable
DEPENDENCY_TREE_LEVEL (or DEPTREE_DEPTH or UPDATE_PRIORITY), which is defined
as 0 if it does not depend on other package (or at level 0 of the dependency
tree), and as [min(DEPENDENCY_TREE_LEVEL of its depended packages) + 1] if
there are depended packages.

So, if we have a bunch of packages, e.g. when the monthly package update email
from Alistair, we can update the packages according to this variable.  That
is, always update the packages with lowest DEPENDENCY_TREE_LEVEL value first.
This will avoid most unnecessary repeats.  

I remember there was a package dependency tree.  I hope it is updeated
regular for this to work.  Also, this is not used directly for package
buildin.  However, I can image we use this to do some dynamic checking before
build (with help of "show-downlevel" taget, maybe).  Also, this does not have
to be a variable in the Makefile, or not even in the Makefile.  It can be in a
text file, such as DESCR.

Anyway, I just think this can be helpful, but there could be dozens of reasons
against this proposal.  Or, it can not done with the existing facility.
Please add your thoughts and lets have a discussion.

          Regards

            Ruibiao

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   Ruibiao Qiu                      ruibiao@arl.wustl.edu
   Research Assistant               ruibiao@cs.wustl.edu
   Applied Research Laboratory      rq1@cec.wustl.edu
   Department of Computer Science   ruibiao@acm.org
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