The document discusses the history and features of the Python programming language. It notes that Python was created in 1991 and describes some of its major releases. It explains that Python is an interpreted, object-oriented language used for tasks like web development, science, and data analysis. The document also provides an overview of Python's syntax, data types, libraries, and learning resources.

1. 24/03/2014 Kevin Van Wilder - Django & Python 1
Python
24-03-2014
Kevin Van Wilder

2. 24/03/2014 Kevin Van Wilder - Django & Python 2
Archeological finds
suggest...
● 1991 Python 1.0
– Guido van Rossum
● 2000 Python 2.0
– Scripting in Operating Systems
– Recent years: Endorsed by Google
● 2005 Django
● 2008 Python 3.0
– Backwards Incompatible
● 2009 MIT switches to Python to teach Computer Science to
students (6.001)

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Python is used for...
● Rapid Prototyping
● Web application development
● Scientific calculations
● XML Processing
● Database applications
● GUI applications
● Glue language for different systems

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What is Python?
● Easy to learn and master
– Clean and clear syntax
– Very few keywords
– High Level data types
– Compact
● Highly portable
– Runs everywhere
● Highly extensible
– Libraries may be written in python or C/C++

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What is Python?
● High Level Programming Language
● Interpreted Language
– Works “similar to Java” behind the scenes
● Source compiles to Bytecode (.pyc files)
● Bytecode is translated on a “virtual machine” as machine code.
– Different implementations of the interpreter:
● CPython (reference implementation)
● Jython (Java-based implementation)
● PyPy (JIT implementation)
● Read-Eval-Print Loop (REPL)

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Variables & Types
● No declaration
● Everything has an object type
● Integer division like in C
● High level data types
– Collections, Lists vs Tuples, Dicts
– Auto unpacking
>>> a = 1
>>> a
1
>>> type(a)
<type 'int'>
>>> a = “Hello”
>>> type(a)
<type 'string'>
>>> 5/2
2
>>> 5.0/2
2.5
>>> x, y = 2, 3
>>> x
2
>>> y
3

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Logic Flow
● For, while loops
● Generators
● Exception Handling
>>> for ch in “Hello”:
… print ch
…
H
e
l
l
o
>>> for i in range(3):
… print i
…
0
1
2
>>>
>>> try:
… connect_to_a_broken_server()
… except ConnectionError as e:
… print “Stuff is broken!”
… finally:
… print “End of the line”
Stuff is broken!
End of the line
>>>

8. 24/03/2014 Kevin Van Wilder - Django & Python 8
Classes
● Class statement
● First class citizen
use as:
– Parameter
– Return value
– Variable assignment
>>> class Foo(object):
…. def __init__(self):
…. self.member = 1
…. def get_member(self):
…. return self.member
….
>>> Foo
<class __main__.Foo at 1000960>
>>> f = Foo()
>>> f
<type 'Foo'>
>>> f.get_member()
1
>>>

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The Language
● Object-Oriented
– Everything is internally an object, even integers and strings
– Supports imperative, functional and procedural development
● Minimalistic
– Indentation defines scoping
– No line delimiters
● Dynamically and Strongly Typed
● Packages, Modules

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Standard Library
● Very large set of modules with diverse
functionality:
– All internet protocols, sockets, cgi, os services
– GUI, database, calendar, file operations
– Debugging, profiling
– Threading, synchronization
● http://docs.python.org/2/library/

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Third party libraries
● Awesome python libraries
– Requests
http://docs.python-requests.org
– Pillow
http://pillow.readthedocs.org
– Dateutil
https://pypi.python.org/pypi/python-dateutil
– DocOpt
https://pypi.python.org/pypi/docopt
● But also:
– And about 40.000+ more!
– Numerical analysis, sql databases, fortran, xml, win32, serial connections, qt,
tkinter, etc etc etc etc etc

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Python is...
● The syntax
● The standard library
● The external library
● The community

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Learning Resources
● “Learn Python The Hard Way” (not really) -
http://learnpythonthehardway.org/
● “Crash Into Python” -
http://www.learnpython.org/
● Read The Fine Manual
http://docs.python.org/