Managing import statements

[Shane Hathaway]

Let's talk about the problem I really want help with.  I brought up a 
proposal earlier, but it was only half serious.  I realize Python is too 
sacred to accept such a heretical change. ;-)

Here's the real problem: maintaining import statements when moving 
sizable blocks of code between modules is hairy and error prone.

I move major code sections almost every day.  I'm constantly 
restructuring the code to make it clearer and simpler, to minimize 
duplication, and to meet new requirements.  To give you an idea of the 
size I'm talking about, just today I moved around 600 lines between 
about 8 modules, resulting in a 1400 line diff.  It wasn't just 
cut-n-paste, either: nearly every line I moved needed adjustment to work 
in its new context.

While moving and adjusting the code, I also adjusted the import 
statements.  When I finished, I ran the test suite, and sure enough, I 
had missed some imports.  While the test suite helps a lot, it's 
prohibitively difficult to cover all code in the test suite, and I had 
lingering doubts about the correctness of all those import statements. 
So I examined them some more and found a couple more mistakes. 
Altogether I estimate I spent 20% of my time just examining and fixing 
import statements, and who knows what other imports I missed.

I'm surprised this problem isn't more familiar to the group.  Perhaps 
some thought I was asking a newbie question.  I'm definitely a newbie in 
the sum of human knowledge, but at least I've learned some tiny fraction 
of it that includes Python, DRY, test-first methodology, OOP, design 
patterns, XP, and other things that are commonly understood by this 
group.  Let's move beyond that.  I'm looking for ways to gain just a 
little more productivity, and improving the process of managing imports 
could be low-hanging fruit.

So, how about PyDev?  Does it generate import statements for you?  I've 
never succeeded in configuring PyDev to perform autocompletion, but if 
someone can say it's worth the effort, I'd be willing to spend time 
debugging my PyDev configuration.

How about PyLint / PyChecker?  Can I configure one of them to tell me 
only about missing / extra imports?  Last time I used one of those 
tools, it spewed excessively pedantic warnings.  Should I reconsider?

Is there a tool that simply scans each module and updates the import 
statements, subject to my approval?  Maybe someone has worked on this, 
but I haven't found the right Google incantation to discover it.

Shane