The Python Programming Language

1
The Python Programming Language

• Jeff Myers

http//milly.rh.rit.edu/python/
Programming Language Concepts, 01/14/2002
2
Python Overview

• Scripting Language
• Object-Oriented
• Portable
• Powerful
• Easy to learn and use
• Mixes good features from Java, Perl and Scheme

3
Major Uses of Python

• System Utilities
• GUIs (Tkinter, gtk, Qt, Windows)
• Internet Scripting
• Embedded Scripting
• Database Programming
• Artificial Intelligence
• Image Processing

4
History of Python

• Created in 1990 by Guido van Rossum
• Named after Monty Python
• First public release in 1991
• comp.lang.python founded in 1994
• Open source from the start

5
Language Features

• Object-Oriented
• Interpreted
• Interactive
• Dynamic
• Functional
• Highly readable

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Built-in Object Types

• Numbers - 3.1415, 1234, 999L, 34j
• Strings - 'spam', "guido's"
• Lists - 1, 2, 'three', 4
• Dictionaries - 'food''spam', 'taste''yum'
• Tuples - (1, 'spam', 4, 'U')
• Files - text  open ('eggs', 'r'). read()

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Operators

• Booleans and or not lt lt gt gt ! ltgt
• Identity is, is not
• Membership in, not in
• Bitwise
• No -- , etc.

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String Operators

• Concatenation
• Repeat
• Index stri
• Slice strij
• Length len( str )
• String Formatting "a s parrot"  'dead
• Iteration for char in str
• Membership m in str

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Common Statements

• Assignment - curly, moe, larry  'good', 'bad', 'u
  gly'
• Calls - stdout.write("spam, ham, toast\n")
• Print - print 'The Killer', joke
• If/elif/else - if "python" in text print text
• For/else - for X in mylist print X
• While/else - while 1 print 'hello'
• Break, Continue - while 1 if not line break
• Try/except/finally - try action() except print '
  action error'

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Common Statements

• Raise - raise endSearch, location
• Import, From - import sys from sys import stdin
• Def, Return - def f(a, b, c1, d) return abcd
• Class - class subclass staticData  
• Global - function() global X, Y X  'new'
• Del - del datak del data ij del obj.attr
• Exec - yexec "import"  modName in gdict, ldict
• Assert - assert X gt Y

11
Samples

• System Utility
• Functional Programming
• Object Oriented networking

12
References

• Python homepage http//www.python.org/
• Jython homepage http//www.jython.org/
• Programming Python and Learning Python
  http//python.oreilly.com/
• This presentation is available from
  http//milly.rh.rit.edu/python/