I once installed a package (pypy) through apt-get but then recklessly decided to delete the pypy directory (/usr/lib/pypy). When I tried to next do the right thing (sudo apt-get remove pypy) I kept getting funny errors from dpkg. It turned out that there was a script (/var/lib/dpkg/info/pypy.prerm) that dpky was using that was confusing it. Removing this script enabled me to clean out the package and then reinstall it properly.
Python's context managers are a very neat way of handling code that needs a teardown once you are done. Python objects have do have a destructor method ( __del__ ) called right before the last instance of the object is about to be destroyed. You can do a teardown there. However there is a lot of fine print to the __del__ method. A cleaner way of doing tear-downs is through Python's context manager , manifested as the with keyword. class CrushMe: def __init__(self): self.f = open('test.txt', 'w') def foo(self, a, b): self.f.write(str(a - b)) def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.f.close() return True with CrushMe() as c: c.foo(2, 3) One thing that is important, and that got me just now, is error handling. I made the mistake of ignoring all those 'junk' arguments ( exc_type, exc_val, exc_tb ). I just skimmed the docs and what popped out is that you need to return True or...
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