But what if someone installs their own, better version of curses, e.g. in /usr/local? Maybe you should only disable it if it's darwin *and* if it's in a standard location? Or if the header file contains a certain characteristic string?

In that case, the user could still put the appropriate instructions into Modules/Setup, which they'd probably do anyway, since they need special -I/-L options. So I agree with the notion that setup.py should only do so much autoconfiguration, and leave special cases to manual configuration through Modules/Setup. However, I dislike the frequent usage of platform in setup.py, where this patch adds another instance of. I believe the autoconf approach "test for features, not system names" is much more flexible. If the curses module requires certain feature, find a way of testing whether the features are present, and only compile _curses if they are. Then it would not be necessary to check whether the system name is "darwin1". This is problematic in particular as different spellings of the platform are expected: It is "darwin1" in some places, and "Darwin1.2" atleast in another place. Regards, Martin