‘And Now For Something Completely Different’ Python Programming David Hartwell Clements

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 2 History of the Snake c Guido van Rossum created Python as a descendant to ABC that would appeal to UNIX/C hackers. Named after Monty Python’s Flying Circus. Python “bridges the gap” between system and scripting languages.

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 3 Languages/Paradigms Studied in MACS400 Prolog –Logical C/C++ –Iterative Java – Object Oriented LISP (Lots of Insanely Stupid Parentheses) –Functional

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 4 So What is Python? “Python is an interpreted, object-oriented, high-level programming language with dynamic semantics.” Python is flexible, powerful, and extremely easy to use. Python is 100% Open Source. Python has elements of Functional, Iterative, and Object Oriented Paradigms.

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 5 Advantages Short Code –3 to 5 times shorter than Java! –5 to 10 times shorter than C++! Extensible using C ‘Executable Pseudocode’ Rapid Prototyping Heavily Cross-Platform (Un*x, MacOS, &c.) Object Oriented

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 6 Object Orientation, “Done Right” Full, Non-Mandated, Support Classes Inheritance and Multiple Inheritance Virtual Methods (pure and otherwise) Operator Overloading

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 7 An Iterative Example answer = ‘’ //default it out while answer != “yellow”: name = raw_input(“What is your name? ”) quest = raw_input(“What is your quest? ”) answer = raw_input(“What is your favorite color? ”) if answer != “yellow”: print “Auuuuuuuuugh” print “Right. Off you go.”

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 8 A Functional Example import shrubbery #This is how we include def function1(x,y): return x * y function2 = lambda x, y: x + y #in-line comments print apply( function1, (3, 5) ) for y in map( function2, (2,3,5), (7,11,13) ): print y

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 9 An Object Oriented Example class Snake: … class Python( Snake ): def __add__( self, other ): self.hunt( other ) … def hunt( target ): … MyPython, MyAsp = Python(), Snake()

6 December 2000Copyright © 2000 David Hartwell Clements, See Notes for Details 10 Getting More Information Any O’Reilly (Animal) book, particularly Programming Python (python on the cover) and Learning Python (rat on the cover).