Issue related to setup_requires (since #1150)

[astrofrog]

For one of the projects I work on (Astropy) we have been making use of code that can be simplified to:

import pkg_resources
from setuptools import Distribution


class CustomDistribution(Distribution):
    def get_option_dict(self, command_name):
        opts = Distribution.get_option_dict(self, command_name)
        if command_name == 'easy_install':
            opts['find_links'] = ('setup script', ['astropy-helpers-2.0.3.tar.gz'])
            opts['allow_hosts'] = ('setup script', '')
        return opts


CustomDistribution(attrs={'setup_requires': ['astropy-helpers']})

print(pkg_resources.working_set.by_key.get('astropy-helpers'))

This requires the following tar file to run: astropy-helpers-2.0.3.tar.gz

Before #1150, this would cause astropy-helpers to be installed to the .eggs directory using the local tar file, but since the changes in #1150 this no longer works (in the above example, the last line used to return a distribution object, but astropy-helpers is now no longer in the working_set so this returns None)

Is this an unintended consequence of #1150, or should we update our code above for it to continue working?

cc @benoit-pierre @jaraco

[benoit-pierre]

Requirements in setup_requires are now installed by setup before creating the Distribution object, not in the Distribution.__init__ phase anymore. Why don't you use setup.cfg and let setup do it for you? Is it because you need astropy-helpers available before calling setup? In which case you can use fetch_build_eggs directly (see example).

[astrofrog]

@benoit-pierre - ok, thanks for the clarification, I'll switch to calling fetch_build_eggs directly instead. We do need astropy-helpers to be available before calling setup. Thanks!