[Distutils] Finding eggs when dependency_links and user specified URLs both given to easy_install?

[Dave Peterson]

What happens if a user specifies a URL via a '-f' option on the 
easy_install command line but our published eggs specify 
dependency_links in the setup.py?   Will easy_install search the user's 
specified location first, last, or will it not search them at all?   
(I'm hoping for the first!)


I'm asking because we want to provide binaries (eggs) of our projects 
for various platforms (RHEL3, RHEL4, RHEL5, Ubuntu 7.04, etc.) all of 
which generate the same egg name, but our projects include C /C++ 
extensions that require compilation for the specific platform, so we've 
structured an egg repository that allows us to separate these 
equivalently named eggs by the actual target platform.   We also want 
users to be able to install from source tar/zip balls for platforms we 
haven't built binaries for yet, so our eggs all include dependency_links 
to point at our egg repo.  Due to issues with build management, we 
aren't currently listing the target platform URLs in each egg's 
setup.py's dependency_links when it gets built on that target platform.  
It just has the source tar/zip ball repository's URL.

But early indications are that when a user installs by doing something like:
    easy_install -f <enthought platform specific repo url> ets==2.5b2
then the first egg gets found properly in the platform specific repo, 
but all of its dependencies are only being searched for in the source 
repo.  Is this just a misinterpretation of the output generated by 
easy_install?

BTW, it would be nice if there was an option to name your generated eggs 
based on a full specification of OS and version, hardware arch, etc.  
And of course, the whole setuptools universe of tools would need to know 
to search for eggs with that level of accuracy before dropping down to 
more generic specs.


Another similar use case:  Some of our users want to locally cache eggs 
for distribution within their corporate environment for various reasons 
(eggs tested and approved to work with their corporate desktop standard, 
etc.)  Those users would also be specifying a '-f' option to 
easy_install to point at their corporate cache.  However, all of our 
eggs will have dependency_links specified.   Will these corporate users 
be able to install and pull things from their local repository, or will 
easy_install always look at our dependency_links' specified locations 
first?  

It doesn't seem convenient to force them to have to remember to provide 
a '-H' setting, though I guess their IT group could create an alias or 
batch script that does this for them.  I also guess that their IT group 
could generate their own version of easy_install that customizes / 
hard-codes the URLs that it would look at, but that seems like kind of a 
long way to go to solve this problem.


-- Dave