On Mon, Jul 22, 2013 at 7:29 AM, Paul Moore <p.f.mo...@gmail.com> wrote: > On 22 July 2013 12:22, Nick Coghlan <ncogh...@gmail.com> wrote: >> >> since extras aren't really a thing in their own right (they're just a >> shorthand for referring to an additional set of dependencies) > > > I'm still trying to be clear in my mind about what extras are, and how they > should work. From this description, it occurs to me to ask, what is the > difference between an extra and a (metadata only, empty) second distribution > that depends on the base project as well as the "additional set of > dependencies"? Is it just the admin overhead of registering a second > project? > > Looking at extras this way gives a possible way of generating scripts only > when the extras are present - just add the scripts to the dummy "extra" > distribution.
Yes, extras are *only* a way to create aliases for a set of dependencies. They are not recorded as installed. It should make no difference whether you install ipython[notebook], look up the dependencies for the ipython notebook and install them manually, or happen to have the ipython[notebook] dependencies installed and then later install ipython itself. What you get is a convenient way to install a distribution's optional dependencies without having to worry about whether the feature's dependencies change. It is a bad idea to make it too easy to install broken versions of distributions having missing scripts. _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org http://mail.python.org/mailman/listinfo/distutils-sig
