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

[Phillip J. Eby]

At 01:38 PM 8/16/2007 -0500, Dave Peterson wrote:
>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!)

The precedence is determined by the versions and urls specifically 
being searched, not by the order in which -f options are 
specified.  The user's -f options will be searched first, but the 
eggs' dependency_links will also be searched.


>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?

Probably; each new set of dependency links is just treated as if they 
were added to the -f list.  And the binary eggs should be given 
preference to the source tarballs, assuming that they are for the 
same target version, or you explicitly request a specific version.


>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.

The optimal spelling of platform strings is an open 
issue.  Unfortunately, I don't have any good solutions, and nobody 
has stepped forward with a solid design proposal.


>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?

The precedence system doesn't work this way; distributions have 
precedence, --find-links and dependency_links don't.  So, unless they 
are requesting a specific version, a newer source version on your 
servers will take precedence over an older binary version on their 
local system.