[Distutils] recommended strategy for missing development tools

[Thomas Kluyver]

On Wed, Jan 25, 2017, at 10:23 AM, Robin Becker wrote:
> The setup.py in question complains if the
> extension files cannot be found, but does not error.

There was a change in pip at some point which means that it only shows
the output from setup.py if running it fails (i.e. it has a non-zero
exit status). I think this was largely because setup.py output is much
more verbose than you usually want, especially if pip installs many
packages at once.

It's nice in some cases where setup.py displays warnings that aren't
really a problem. In one project I maintain, a particular submodule
requires Python 3, while the rest of the code can be used on Python 2 as
well; people with older versions of pip have complained that it 'fails
to install', which it doesn't, because the warning looks like a fatal
error.

However, the flip side of this is that, as far as I know, setup.py has
to choose between succeeding silently, or failing and showing the user
an error message.

Thomas