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Python Guido van Rossum director of PythonLabs at Zope Corporation

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Presentation on theme: "Python Guido van Rossum director of PythonLabs at Zope Corporation"— Presentation transcript:

1 Python Guido van Rossum director of PythonLabs at Zope Corporation

2 Slide 2©2001, 2002 Guido van Rossum

3 Slide 3©2001, 2002 Guido van Rossum Whats in a name? Snake logos and mascot notwithstanding, its named after Monty Pythons Flying Circus Humor-impaired can safely ignore the spam references :-) Nobody expects the Spanish inquisition

4 Slide 4©2001, 2002 Guido van Rossum What is Python? O-O rapid prototyping language Not just a scripting language Not just another Perl Easy to learn, read, use Extensible (add new modules) –C/C++/Fortran/whatever –Java (through Jython) Embeddable in applications

5 Slide 5©2001, 2002 Guido van Rossum Touchy-feely properties Open Source (OSI Certified) –copyrighted but use not restricted –no "viral" license –owned by independent non-profit, PSF Mature (13 years old) Supportive user community –plenty of good books, too Simple design, easy to learn –reads like pseudo-code –Suitable as first language –Suitable as last language :-)

6 Slide 6©2001, 2002 Guido van Rossum High-level properties Extremely portable –Unix/Linux, Windows, Mac, PalmOS, WindowsCE, RiscOS, VxWorks, QNX, OS/2, OS/390, AS/400, PlayStation, Sharp Zaurus, BeOS, VMS… Compiles to interpreted byte code –compilation is implicit and automatic Memory management automatic –reference counting for most situations –GC added for cycle detection Safe: no core dumps due to your bugs

7 Slide 7©2001, 2002 Guido van Rossum What is it used for? rapid prototyping web programming (client and server side) ad hoc programming ("scripting") steering scientific applications extension language XML processing database applications GUI applications education

8 Slide 8©2001, 2002 Guido van Rossum Who is using it? Google (various projects) NASA (several projects) NYSE (one of only three languages "on the floor") Industrial Light & Magic (everything) Yahoo! (Yahoo mail & groups) RealNetworks (function and load testing) RedHat (Linux installation tools) LLNL, Fermilab (steering scientific applications) Zope Corporation (content management) ObjectDomain (embedded Jython in UML tool) Alice project at CMU (accessible 3D graphics) More success stories at

9 Slide 9©2001, 2002 Guido van Rossum Language properties Everything is an object Packages, modules, classes, functions Exception handling Dynamic typing, polymorphism Static scoping Operator overloading Indentation for block structure –Otherwise conventional syntax

10 Slide 10©2001, 2002 Guido van Rossum High-level data types Numbers: int, long, float, complex Strings, Unicode: immutable Lists and dictionaries: containers Other types for e.g. binary data, regular expressions, introspection Extension modules can define new built-in data types

11 Slide 11©2001, 2002 Guido van Rossum Interfaces to... XML –DOM, expat –XMLRPC, SOAP, Web Services Relational databases –MySQL, PostgreSQL, Oracle, ODBC, Sybase, Informix Java (via Jython) Objective C COM, DCOM (.NET too) Many GUI libraries –cross-platform Tk, wxWindows, GTK, Qt –platform-specific MFC, Mac (classic, Cocoa), X11

12 Slide 12©2001, 2002 Guido van Rossum Compared to Perl Easier to learn –very important for infrequent users More readable code More maintainable code Fewer magical side effects More safety guarantees Better Java integration

13 Slide 13©2001, 2002 Guido van Rossum Compared to Java Code up to 5 times shorter –and more readable Dynamic typing Multiple inheritance, operator overloading Quicker development –no compilation phase –less typing Yes, it may run a bit slower –but development is much faster –and Python uses less memory (studies show) Similar (but more so) for C/C++

14 Slide 14©2001, 2002 Guido van Rossum Jython Seamless integration with Java Separate implementation Implements the same language Different set of standard modules differences in gray areas –e.g. some different introspection calls –different command line options, etc.

15 Slide 15©2001, 2002 Guido van Rossum Jython's Java integration Interactive Compiles directly to Java bytecode Import Java classes directly Subclass Java classes –pass instances back to Java Java beans integration Can compile into Java class files

16 Slide 16©2001, 2002 Guido van Rossum Example function def gcd(a, b): "greatest common divisor" while a != 0: a, b = b%a, a # parallel assignment return b

17 Slide 17©2001, 2002 Guido van Rossum Example class class Stack: "A well-known data structure" # doc string def __init__(self): # constructor self.items = [] def push(self, x): self.items.append(x) # the sky is the limit def pop(self): x = self.items[-1] # what happens if its empty? del self.items[-1] return x def empty(self): return len(self.items) == 0

18 Slide 18©2001, 2002 Guido van Rossum References and plugs References: – - Python home site documentation, downloads, community, PSF – - success stories – - interview with GvR – - Zope community site – - Zope corporate site Python Conferences (see –PyCon DC March Washington, DC on-line registration ends today ($200) –Python UK April 2-3 Oxford, England –EuroPython June Charleroi, Belgium –Python11 at OSCON July 7-11 Portland, OR

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