Python @ PiTech - March 2009

PiTechnologies

Tudor ProdanMarch 2009

What is Python

- a “very high-level language”- developed by Guido van Rossum - main features:

simple, yet powerful semantics object-oriented, but multi-paradigm clean syntax and coherent design focus on productivity rich standard library lots of high quality 3rd-party several good implementations:

CPython, Pypy, IronPython (2.0.1), PyS60, Jython

Jython

Jython, lest you do not know of it, is the most compelling weapon the Java platform has for its survival into the 21st century :-)

—Sean McGrath, CTO, PropylonJuly 31, 2003

CPython

Version history:1.0 – Jan 19942.0 – Oct 20003.0 – Dec 2008

Latest stable versions:2.6.1 and 3.0.1

Usable versions:2.5.x2.6.x = 2.5 + improvements + 3.0 features

(__future__)| | |__ maintenance version| |____ minor version|______ major version

Why Python?

Why Python

programming is fun again

Unfinished game

The problem of the unfinished game:

Let's say, hypothetically speaking, you met someone who told you they had two children, and one of them is a girl.

What are the odds that person has a boy and a girl?

-Jeff Atwood, December 30, 2008http://www.codinghorror.com/blog

Unfinished game

Java

Unfinished game

C#

Unfinished game

Python

Unfinished game

LoC readable? fun?

Java 53 barely nope

C# 49 kind of not really

Python 10 clean, much more fun concise than the above

Why Python

programming is fun again agility elegance you don't have to fight the language

Why Python

Java is the COBOL of the 21st century.

-Sean Kelly, JPL, NASA

Spirit of C

Python is close to the “Spirit of C” (more than C++/ Java/...), as per ISO C Standard's “rationale”:

trust the programmer don't prevent the programmer from doing what needs to be done keep the language small and simple provide only one way to do an operation make it fast, even if it's not guaranteed to be portable (the only bit not @100% in Python)

Python vs. C(++,#)/Java/..

everything is a first-class object - functions, methods, modules, ..

typing: strong, but dynamic - names have no type, objects have types

no “declarations”, just statements - implicit compilation, .pyc files - everything is run-time (compile-time too)

spare syntax, minimal ornamentation - no { } for blocks - no ( ) for conditions - a lot less punctuation

Python vs. C(++,#)/Java/..

In the 1960's the KGB was very interested in learning everything possible about the American space program, sending all sorts of spies to find every possible piece of information.

One afternoon, a breathless spy returned to headquarters with a piece of paper in his hand, excitedly shouting to his superior, "Comrade! Comrade! The Americans are using Lisp to write their rocket launching software!“

The commander was skeptical. "How do you know?"

"I broke into their research lab and stole a page from the teletype machine! It's not the whole program, but it's the final page and contains the concluding logic of the program! See for yourself!"

The commander looked at the page and smiled:

Python vs. C(++,#)/Java/..

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Why Python

Example #2:

Create a Coordinate class which holds a latitude and longitude, to be used by a TelemetryTracker object.

Why Python

this example will show Python vs. Java

but is actually Python vs. Java / C# / PHP / (most others)

Why Python

Java:

Philosophy

You know you've reached perfection in design, not when you have nothing more to add, but when you have nothing more to take away.

-Antoine de Saint Exupery

Why Python

Java: Python:

Why Python

The Java guys will say:

my IDE can generate most of that - code is read a lot more than written

Why Python

The Java guys will say:

my IDE can generate most of that - code is read a lot more than written

but, your fields are public - Python philosophy

Why Python

The Java guys will say:

my IDE can generate most of that - code is read a lot more than written

but, your fields are public - Python philosophy

can't we apply this to other languages?

Why Python

Java: Python:

Why Python

Eventually, the code will end up in production..

Java: Python:

Why Python

.. time passes ..

Why Python

.. time passes ..

Eventually,decodeLat receives bad data

This is a bug!

What do we do?

- add a check

Why Python

Add a setter and a getter:

Why Python

Add a setter and a getter:

Let's try it out:

Why Python

and the TelemetryTracker code:

Python:- still works

Java:- needs modification

Why Python

in the end:

Python:- gives you a choice- you can even change your mind

Java/C#/PHP/..:- no choice

Why Python

programming is fun again agility elegance you don't have to fight the language the language trusts you .. it accommodates you

Why Python

programming is fun again agility elegance you don't have to fight the language the language trusts you .. it accommodates you .. and will not go out of it's way to stop you

Why Python

Python haslots & LOTSof good books:

Why Python

programming is fun again agility elegance you don't have to fight the language the language trusts you .. it accommodates you .. and will not go out of it's way to stop you good documentation (lots of books) good support: lots of forums, mailing lists, IRC

Why Python

Large number of high quality 3rd-party libraries and frameworks:

- networking: twisted, cogen, concurrence- scientific: NumPy, ScyPy, PyEvolve (genetic algorithms)- testing: PyUnit, Google Mox- fuzzing: Fuzz- database: SQLAlchemy, Elixir, Django ORM- web crawling: BeautifulSoup, lxml, Scrappy- game development: PyGame- GUI: PyGTK, wxPython, PyQt, GTK#-templating: Genshi, Mako, Kid, Jinja2- cryptography: M2Crypto, PyCrypto, Keyczar,

.. many, many others

Why Python

programming is fun again agility elegance you don't have to fight the language the language trusts you .. it accommodates you .. and will not go out of it's way to stop you good documentation (lots of books) good support: lots of forums, IRC, mailing lists lots of high quality 3rd-party libraries

Why Python

But most interesting to us,lots of great web frameworks:

Why Python

programming is fun again agility elegance you don't have to fight the language the language trusts you .. it accommodates you .. and will not go out of it's way to stop you good documentation (lots of books) good support: lots of forums, IRC, mailing lists lots of high quality 3rd-party libraries many great web frameworks