jonathan huelman csc 415 – programming languages python
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Jonathan Huelman
CSC 415 – Programming Languages
Python
Introduction to Python
Named for Monty Python’s Flying Circus, the British sketch comedy TV show
Defined as a very high-level scripting language, there isn’t a lot Python
can’t do with it’s extensive standard library
Python is interpreted, meaning each line is indirectly executed.
There is no byte code
“Batteries included”
History of Python
Guido Van Rossum, BDFL (Benevolent Dictator For Life)
Python based on ABC, first created in the late 1980s
The Python Software foundation launched in March 2006 with Van Rossum as President. It is a non-profit organization dedicated to the Python programming language
Release dates for the major versions:Python 1.0 - January 1994
Python 2.0 - October 16, 2000Python 3.0 - December 3, 2008
Who Uses Python
Graphics Industrial Light and Magic Walt Disney Feature Animation
Games Battlefield 2 Civilization 4
Web Development Yahoo Maps Google Linux Weekly News
Mathematical libraries Matplotlib, which is like MATLAB NumPy, a language extension that adds
support for large and fast, multi-dimensional arrays and matrices
PyIMSL Studio is a Python distribution which includes the IMSL Numerical Libraries.
The Zen of Python
>>> import this
The Zen of Python, by Tim Peters
Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!
>>>
‘Pythonic’ Code
1. for (i=0; i < mylist_length; i++)
{ do_something(mylist[i]); }
2. i = 0 while i < mylist_length: do_something(mylist[i]) i += 1
3. for i in range(mylist_length): do_something(mylist[i])
4. for element in mylist: do_something(element)
Example – Regular Expressions
More Examples
http://wiki.python.org/moin/SimplePrograms
http://code.activestate.com/recipes/577905-password-generator/?in=lang-python
Primes program
beers on the wall and a more ‘pythonic’ version
Guessing game
Pros on Python
Why Reddit uses Python“The biggest thing that has kept us on Python … ...
One are the libraries. There’s a library for everything. We’ve been learning a lot of these technologies and a lot of these architectures as we go.
The other thing that keeps us on Python, and this is the major thing, is how readable and writable it is. When we hire new employees ... it’s awesome because I can see from across the room, looking at their screen, whether their code is good or bad. Because good Python code has a very obvious structure.”
- Steve Huffman, Web Developer, Co-Founder of Reddit.com
Evaluation
very clear, readable syntax, once you get used to the fact that indentation is key to syntax
intuitive object orientation natural expression of procedural code full modularity, supporting hierarchical packages exception-based error handling very high level dynamic data types extensive standard libraries and third party modules for
virtually every task embeddable within applications as a scripting interface free, with relatively cheap IDEs available on the Internet
Sources
http://faassen.n--tree.net/blog/view/weblog/2005/08/06/0
http://brainsik.theory.org/.:./2009/why-reddit-uses-python
http://www.yak.net/fqa/171.html
http://www.python.org/
http://en.wikipedia.org/wiki/Python_(programming_language)