[Biopython-dev] Plan for upgrade

Dragoslav Zaric zaricdragoslav at gmail.com
Tue Oct 26 07:24:50 UTC 2010

Dear Peter,

This is what I found on python 3 web pages:
Porting To Python 3.0
For porting existing Python 2.5 or 2.6 source code to Python 3.0, the
best strategy is the following:

(Prerequisite:) Start with excellent test coverage.
Port to Python 2.6. This should be no more work than the average port
from Python 2.x to Python 2.(x+1). Make sure all your tests pass.
(Still using 2.6:) Turn on the -3 command line switch. This enables
warnings about features that will be removed (or change) in 3.0. Run
your test suite again, and fix code that you get warnings about until
there are no warnings left, and all your tests still pass.
Run the 2to3 source-to-source translator over your source code tree.
(See 2to3 - Automated Python 2 to 3 code translation for more on this
tool.) Run the result of the translation under Python 3.0. Manually
fix up any remaining issues, fixing problems until all tests pass
It is not recommended to try to write source code that runs unchanged
under both Python 2.6 and 3.0; you’d have to use a very contorted
coding style, e.g. avoiding print statements, metaclasses, and much
more. If you are maintaining a library that needs to support both
Python 2.6 and Python 3.0, the best approach is to modify step 3 above
by editing the 2.6 version of the source code and running the 2to3
translator again, rather than editing the 3.0 version of the source

And this is page for 2to3 translator:


So can we start to agree on approach and tactics.

Kind regards
Dragoslav Zaric

Professional Programmer
MSc Astrophysics

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