Python Programming Language

Python Programming LanguageCreated in 1991 by Guido Van Rossum

Python Programming LanguageGeneral Purpose LanguageClean Syntax

Python Programming LanguageGeneral Purpose LanguageClean SyntaxEasy to Learn

Python Programming LanguageGeneral Purpose LanguageClean SyntaxEasy to LearnEasy to Debug

Python Programming LanguageGeneral Purpose LanguageClean SyntaxEasy to LearnEasy to DebugNatural Feeling

Python Programming LanguageGeneral Purpose LanguageInterpreted

Python Programming LanguageGeneral Purpose LanguageInterpretedNo Compilation Phase

Python Programming LanguageGeneral Purpose LanguageInterpretedNo Compilation PhaseMultiplatform Integration

Python Programming LanguageGeneral Purpose LanguageInterpretedNo Compilation PhaseMultiplatform IntegrationNative Debugger

Python Programming LanguageGeneral Purpose LanguageInterpretedDuck Typing

Python Programming LanguageGeneral Purpose LanguageInterpretedDuck TypingOverride behaviours by creating methods

Python Programming LanguageGeneral Purpose LanguageInterpretedDuck TypingOverride behaviours by creating methodsImplement operations by creating methodst

Python Programming LanguageGeneral Purpose LanguageInterpretedDuck TypingOverride behaviours by creating methodsImplement operations by creating methodsAll data is an object

Python Programming LanguageObjects are Pythons abstraction for data. All data in a Python program is represented by objects or by relations between objects.

Every object has an identity, a type and a value.

Python Programming LanguageAn objects identity never changes once it has been createdThe is operator compares the identity of two objects The id() function returns an integer representing its identity

Python Programming LanguageAn objects identity never changes once it has been createdThe is operator compares the identity of two objects The id() function returns an integer representing its identityAn objects type is also unchangeable. The type() function returns an objects type (which is an object itself).

Python Programming LanguageGeneral Purpose LanguageInterpretedDuck TypingStrongly Typed

Python Programming LanguageA Python programmer can write in any style they like, using design patterns borrowed from:Imperative DeclarativeObject Orientedfunctional programming The author is free let the problem guide the development of the solution.

Python Programming Languageprint('hello world')

class Hello(object): def __init__(self, my_string): self.my_string = my_string def __call__(self, render_func): out_str = 'Hello %s' % self.my_string render_func(out_str)

def print_string(string_to_print): print(string_to_print)

myHelloWorldClass = Hello('world')myHelloWorldClass(print_string)

Functional ExampleJava:public class OuterClass { // Inner class class AddN { AddN(int n) { _n = n; } int add(int v) { return _n + v; } private int _n; } public AddN createAddN(int var) { return new AddN(var); } } LISP(define (addn n) (lambda (k) (+ n k))) Pythonaddn = lambda n: lambda x: x + nOrdef addN(n): def add_n(x): return x + n return add_n

Modular DesignThe standard Python interpreter (CPython) is written in C89It is designed with two-way interfacing in mind:Embedding C programs in PythonEmbedding Python programs in C

Modular Design

An Example C Module#include

static PyObject *spam_system(PyObject *self, PyObject *args){ const char *command; int sts;

if (!PyArg_ParseTuple(args, "s", &command)) return NULL; sts = system(command); return Py_BuildValue("i", sts);}

/*********************************************************** import spam **** spam.system( **** 'find . -name "*.py" **** -exec grep -Hn "Flying Circus" {} \;') ***********************************************************/

Cross Platform ExecutionThe CPython interpreter can be built on most platforms with a standard C library including glibc and uclibc.

Cross Platform ExecutionInterpreters such as Jython and IronPython can be used to run a python interpreter on any Java or .NET VM respectively.

Python Is Good ForProtyping

Python Is Good ForProtypingWeb Applications/SAS

Python Is Good ForProtypingWeb Applications/SASIntegration

Python Is Good ForProtypingWeb Applications/SASIntegrationTransport Limited Applications

Python Is Good ForProtypingWeb Applications/SASIntegrationTransport Limited ApplicationsIndeterminate Requirements

Python Is Good ForProtypingWeb Applications/SASIntegrationTransport Limited ApplicationsIndeterminate requirements Short Relevence Lifetime

Python Is Good ForProtypingWeb Applications/SASIntegrationTransport Limited ApplicationsIndeterminate requirements Short Relevence LifetimePorting Legacy Applications

Python Is Good ForProtypingWeb Applications/SASIntegrationTransport Limited ApplicationsIndeterminate requirements Short Relevence LifetimePorting Legacy ApplicationsGlue

Python is Not Good ForNative Cryptography

Python is Not Good ForNative CryptographyMILOR

Python is Not Good ForNative CryptographyMILORHighly Parallel Design

__Types__None

__Types__NoneNotImplemented

__Types__NoneNotImplementedBoolean

__Types__NoneNotImplementedBooleanInt/LongInt

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...

__Types__Sequencesstringunicodebytestuplelistsetfrozenset

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)Functions and Methods

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)Functions and MethodsGenerators

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)Functions and MethodsGeneratorsModules

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)Functions and MethodsGeneratorsModulesFile/Buffer

__Types__NoneNotImplementedBooleanInt/LongIntFloat (which is really a double)Complex (double +doubleJ)Sequences...Mapping Types (dict)Functions and MethodsGeneratorsModulesFile/BufferType (metaclasses)

Special Duck Methods__abs__ __add____and____iter____getitem____iter____del____cmp__!__hash____lt__For Example

Example Codeclass Foo: baz = 'monkey' def bar(self): self.printFunc(self.text)

foo = Foo()foo.text = 'Hello World'

def print_console_factory( filter_func=lambda a: a ): def print_console(text): print(filter_func(text)) return print_console

foo.printFunc = print_console_factory()

print_hello_world = foo.barprint_hello_world()

>>> Hello World

vowels = [ 'a', 'e', 'i', 'o', 'u' ]filter_vowels = lambda a: ''.join([ let for let in a if not let.lower() in vowels ])foo.printFunc = print_console_factory(filter_vowels)print_hello_world()

>>>Hll Wrld

Python Resources

Python.org Documentation http://www.python.orgPython.org PEPs http://www.python.org/dev/peps/Ye Olde Cheese Shoppe http://pypi.python.org/pypi

Alternate ImplementationC APIhttp://docs.python.org/extendingCreate C ModulesExecute Python within a C applicationInterface via a C API

Alternate ImplementationJythonhttp://www.jython.org/ProjectNative JVM Python interpreterFull support for standard libraryOther C Extensions may not be portedPython extensions may rely on C extensions

Alternate ImplementationPyPyhttp://codespeak.net/pypy/dist/pypy/doc/Python interpreter written in pythonFramework interprets multiple languagesHighly extendableSlow

Alternate ImplementationPsycohttp://psyco.sourceforge.netActually a C moduleProduces highly optimized C code from python bytecodeExcellent performance characteristicsConfigurable

Alternate ImplementationIronPythonhttp://codesplex.com/Wiki/View.aspx?ProjectName=IronPythonNative python interpreter (C#) for .NETFull support for standard libraryMany external modules have been portedPorting modules is quite simpleCan integrate with .NET languages

Alternate ImplementationPyJamashttp://code.google.com/p/pyjamas/Python interpreter for JavaScriptCross browser fully supportedAs lightweight as you'd thinkJSON/JQuery may be a better option

Alternate ImplementationShedSkinhttp://code.google.com/p/shedskin/Produces C++ code from Python codeExcellent for prototypingSome language features not supportedImplicit static typed code only

Alternate ImplementationCythonhttp://www.cython.orgEmbed C code in a python applicationExcellent for use in profilingCompiled at first runtimeShared build env with python interpreter

Hosting Pythonmod_pythonBy far most common hosting mechanismhttp://modpython.orgApache2 specificInterpreter embedded in webserver workerMemory intensiveFast

Hosting PythonWSGIUp and coming for a good reasonhttp://code.google.com/p/modwsgi/http://code.google.com/p/isapi-wsgi/Can embedded interpreterCan run threaded standalong app serverVery fast and inexpensiveSandboxing supported

Hosting PythonFastCGIMature and stableRequires no 3rd party modules for most webserversFast and inexpensiveSandboxing supported

Hosting PythonCGIMature and stableSupported on nearly all platformsVery flexible in terms of hosting requirementsSlow

Web FrameworksDjangohttp://www.djangoproject.com/Active user communityWell documentedCurrently under active developmentExtensive meta and mock classesClean layer separation

Web FrameworksDjangoData LayerBusiness LogicControl LayerPresentation Layer

Not just for the web

Web FrameworksTurbogears CherryPyhttp://www.turbogears.orgPersistent app serverJavascript integration via mochikitFlexible DB backend via SQLObject

Web FrameworksPylons - Pastehttp://www.pylonshq.org/Multiple DB Backends supportedMultiple templating languages pluggableMultiple request dispatchingHTTP orientedForward compatibleMVC Type layer separation

Web FrameworksZopehttp://www.zope.orgWeb Application FrameworkHighly Web OrientedNot lightweightHighly FeaturefulZDB Data store backend

Web FrameworksZopehttp://www.zope.orgWeb Application FrameworkHighly Web OrientedNot lightweightHighly FeaturefulZDB Data store backend