Python Programming Language Overview

1. Python Henry Armstrong Andy Burras Everett Hite

2. History • First released in 1991 by Guido van Rossum • Designed around a philosophy which emphasized readability and importance of programmer effort over computer effort • Minimalist syntax and semantics • Large standard library is comprehensive • It was influenced by ALGOL 68, C, Lisp, Perl and Java • It was originally developed for UNIX scripting, but eventually grew beyond these bounds

3. Concepts • Multi-paradigm language focusing on functional, object oriented and imperative • Has a fully dynamic type system. This means that type checking is done during runtime • Variables are strongly typed. This forbids operations which make little or no sense (i.e.; cannot perform int + char) • Has automatic memory management • Has a highly readable, uncluttered language. Uses many English keywords where other languages use punctuation

4. Implementations • YouTube and the original BitTorrent client were programed in python. • Google and NASA use python for a variety of things • Python is embedded in a number of software packages including ArcGIS (a GIS package) and Maya (a high-end 3D animation package) • Python is also used for scripting in a number of video games, including Civilization IV, Eve Online and Battlefield 2

5. Code Example print "This is a factorial program.“ n = -1 #Initialize n for error checking while n < 0: #Ensure that only nonnegative numbers will be accepted n = input( "What number do you want to factorialize?" ) temp = n #Initialize return value (temp) and the counter count = n – 1 if n == 0: #Account for special case 0! = 1; set temp, count to 1 temp = 1 count = 0 while count > 0: #Calculate n factorial temp = temp * count count = count – 1 print n,"! =",temp #Print result

6. Comparison to Other Languages The following programs will count from 0 to 1000000 and print them out to a file Java: import java.io.*; public class test{ public static void main(String[] args){ try{ File f = new File("/tmp/scratch"); PrintWriter pw = new PrintWriter(new BufferedWriter( new FileWriter(f))); for(int i = 0; i < 1000000; i++){ pw.print(i); } pw.close(); } catch(IOException ioe){ ioe.printStackTrace(); } } } Python: f=open(‘/tmp/scratch’,’wb’) For i in xrange(1000000): f.write(str(i)) f.close() C++: #include <iostream.h> #include <fstream> using namespace std; int main(int argc, char *argv[]){ ofstream out; out.open("/tmp/scratch"); for(int i = 0; i < 1000000; i++){ out << i; } out.close(); }

7. Comparisons (cont’d) To Java: • Python typically run slower than equivalent Java programs • The development process for Python is significantly shorter than that of Java • Actual code length of Python is 3-5 times shorter than equivalent Java code To C++: • Python compared to C++ is similar to Python compared to Java, just to a greater extent. • Actual code length of Python is 5-10 times shorter than equivalent C++ code • Python is sometimes referred to and used as a glue language that combines several component written in C++ To Perl: • Both share similar roots (Unix, scripting), and similar features. • Perl is harder to maintain based off the sometimes cryptic syntax and multiple operators

8. SOURCES http://www.razorvine.net/python/PythonComparedToJava http://www.wikipedia.com/Python_(programming_language) http://furryland.org/~mikec/bench http://www.python.org