This Tutorial
Mastering Python 3 I/O
David Beazley
Presented at PyCon'2010 Atlanta, Georgia
Copyright (C) 2010, David Beazley,
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This Tutorial
? It's about a very specific aspect of Python 3 ? Maybe the most important part of Python 3 ? Namely, the reimplemented I/O system
Copyright (C) 2010, David Beazley,
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Why I/O?
? Real programs interact with the world ? They read and write files ? They send and receive messages ? They don't compute Fibonacci numbers
? I/O is at the heart of almost everything that Python is about (scripting, gluing, frameworks, C extensions, etc.)
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Copyright (C) 2010, David Beazley,
The I/O Problem
? Of all of the changes made in Python 3, it is my observation that I/O handling changes are the most problematic for porting
? Python 3 re-implements the entire I/O stack ? Python 3 introduces new programming idioms ? I/O handling issues can't be fixed by automatic
code conversion tools (2to3)
Copyright (C) 2010, David Beazley,
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The Plan
? We're going to take a detailed top-to-bottom tour of the whole Python 3 I/O system ? Text handling ? Binary data handling ? System interfaces ? The new I/O stack ? Standard library issues ? Memory views, buffers, etc.
Copyright (C) 2010, David Beazley,
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Prerequisites
? I assume that you are already reasonably familiar with how I/O works in Python 2 ? str vs. unicode ? print statement ? open() and file methods ? Standard library modules ? General awareness of I/O issues
? Prior experience with Python 3 not required
Copyright (C) 2010, David Beazley,
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Performance Disclosure
? There are some performance tests
? Execution environment for tests:
? 2.4 GHZ 4-Core MacPro, 3GB memory
? OS-X 10.6.2 (Snow Leopard)
? All Python interpreters compiled from source using same config/compiler
? Tutorial is not meant to be a detailed performance study so all results should be
viewed as rough estimates
Copyright (C) 2010, David Beazley,
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Let's Get Started
? I have made a few support files:
? You can try some of the examples as we go ? However, it is fine to just watch/listen and try
things on your own later
Copyright (C) 2010, David Beazley,
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Part 1
Introducing Python 3
Copyright (C) 2010, David Beazley,
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Syntax Changes
? As you know, Python 3 changes syntax ? print is now a function print()
print("Hello World")
? Exception handling syntax changed slightly
try:
added
...
except IOError as e:
...
? Yes, your old code will break
Copyright (C) 2010, David Beazley,
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