[Distutils] Optional C extensions in packages
jim at zope.com
Fri Feb 2 19:26:12 CET 2007
Phillip J. Eby wrote:
> At 08:11 AM 2/2/2007 -0500, Jim Fulton wrote:
>> Phillip J. Eby wrote:
>>> At 05:32 PM 2/1/2007 -0500, Jim Fulton wrote:
>>>> I'm still worried about the ambiguous case when there are both
>>>> platform-dependent and platform-independent eggs installed.
>>> How would this happen?
>> At least in a couple of ways.
>> 1. As I mentioned in my previous note, when a package has optional
>> extensions, one will often want to disable the extensions for
>> debugging purposes. It is easier debugging Python code than
>> C code, especially in combination with other Python code. In the
>> past, this was typically done by removing .so (or .pyd) files.
>> This can still be done with eggs, but I thik it will be attractive
>> to do this by selecting diffeent eggs.
>> 2. Consider the following scenario: Someone has a mac without a
>> environment installed. They install some eggs and get versions
>> extensions. Later, they install the development tools that came on
>> the CD
>> with their mac. How do they reinstall the eggs with extensions?
>> If they
>> install in multi-version mode, won't they have a mix of eggs with and
>> without extensions?
> Well, they can always "rm -rf *.egg" and reinstall. :) Otherwise,
> they'll get them by attrition when packages are upgraded to newer
> versions. In fact, using -U might be sufficient, although I think
> EasyInstall actually has some quirks with respect to determining whether
> -U will end up in a reinstall or not.
I'd be surprised if upgrade would reinstall if there weren't a later version
>> I see your point. This arises from the way that easy_install
>> installs distributions. This potentially wouldn't be a problem for
>> but I wouldn't want to break easy_install (or workingenv).
> Yes, so these features would have to wait until 0.7, and a possible
> redesign of EasyInstall to be based on buildout (or something like it,
> anyway), instead of the other way around. ;)
I didn't mean to imply that buildout was better than easy_install,
merely noting that they were different.
>>> Sigh. I guess at this point I don't really see a way to do optional
>>> extensions that doesn't turn into a crazy madhouse of support later.
>>> It seems to me that at least the problems with my approach would at
>>> most boil down to, "how come this thing is so slow"? :)
>> OK, so based on this discussion, I'm in favor of your original proposal
>> as a start. I think there should be a way to cause building/installation
>> of a platform-dependent egg even if there is a platform-independent egg
>> with the same installed already, and the other way around, to deal with
>> the use cases I described earlier. Even in multiple-version mode,
>> this is not a problem, because the eggs will have different file names.
>> I'd really *like* to be able to reflect the selection of these somehow
>> in requirement specifications, but, if need be, this can be dealt with
>> at the tool (e.g. buildout) level.
> EasyInstall probably just needs to grow an option to force
> reinstallation of a package, as that's a generally useful feature.
> I.e., sort of a "don't allow the requirement to be satisfied with an egg
> that's already on sys.path" option.
That seems like a rather big stick and a round-about way to do it.
Jim Fulton mailto:jim at zope.com Python Powered!
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