astropy/astropy — pull request #326 by iguananaut (2012-07-27 18:31:07+00:00)
Title: Alternative fix for #320

This implements the alternative fix I discussed in #320, which delays importing numpy until build time.

Unfortunately this still does not fix the issue. When pip installs a requirements file it does not (as far as I know) know about build-time requirements. So it does not know that Astropy actually requires Numpy to *build*. So when it goes to install the requirements, in order to "help" you and prevent incomplete installations it does the following:

download each package =>
if downloads succeed get the pkg-info for each package (running egg_info) =>
if pkg-info succeeds build each package =>
if all packages build successfully install each package

So it builds Numpy, and then builds Astropy before Numpy is installed.

What pip is doing is fairly sensible here, but it's too bad there isn't some way to specify build-time dependencies through a requirements file. I *think* I might still be able to hack around this, but I'm not sure yet...