[plt-dev] planet remove and scribble

On Fri, Feb 6, 2009 at 2:32 PM, Robby Findler
<robby at eecs.northwestern.edu> wrote:
> On Fri, Feb 6, 2009 at 1:22 PM, Carl Eastlund <cce at ccs.neu.edu> wrote:
>> Hmm.  It does need to rebuild the index.  And it needs to rebuild the
>> index without the package being removed.  But it doesn't want to
>> reinstall the package if anything has a dependency on it... so it
>> leaves the package installed.  That much makes sense.  Is there a way
>> to do that, and either rebuild only the index (not any code /
>> documentation) or else, when rebuilding other code, not follow
>> dependencies into the package being removed?  I can see why it's doing
>> some rebuilding, and why the package is still in place, but it seems
>> unfortunate that it gets pulled into the actual build process.
>>
>> We could try another tack.  Remove the package, rebuild, but change
>> the module resolver while rebuilding so that it reports an error
>> during any attempts to retrieve that planet package.  That would
>> rebuild as much of the index as possible without the package, wouldn't
>> traverse the package itself, and wouldn't replace it with any new
>> download.
>
> That seems like an interesting thing to try. The idea is that error
> should never be signaled, right?

No, the error may be signaled.  You may have A:1.0 and B:1.0 that
depends on A:1.0+.  To upgrade A, you might first remove A:1.0 and
then install A:1.1.  While removing A:1.0, B:1.0 will signal an error
because nothing satisfies its dependence on A.  But that's an ok error
to signal, it shouldn't interrupt setup-plt, but it does let the user
know they have to replace A as their next step.

If we're not trying to support this behavior of "remove a middle
dependency and replace it later" -- which breaks down with multiple
parts to the dependency anyway -- we should just remove the package
outright and run setup-plt, and if anything depends on it that causes
a re-download, the user "just shouldn't do that".

Or, rather than special casing that you can't load that package,
perhaps we should just disable the planet installation mechanism
during planet remove -- no package should be installed, from web or
from cache, during a remove.

--Carl