Module

 

Module

 

Till now we discussed about the Function, but at times we may require the Function defined in an Application to be used in another one. One way, is to redefine the Function once again at the required place. The other way is , to save the function as a Module and include it any Application in which it is required.

 

What is a Module?

 

The Module is nothing but a File where one or more related Functions and also Classes are defined. It is considered as Library file, which can be included in any Application.

 

Again like in Functions, Modules can also be of 2 types System Defined and User Defined.

 

The module has to be imported into the current program before using it. To import a Module use the following syntax,

 

Syntax

 

import <module name>

 

     Once the module is successfully imported we can use the function. But at times, a same Function name may be available in 2 or more modules. The better programming practice is to use the Function name along with Module name to avoid any ambiguity.

 

Characteristics of Module

 

]The module can have any number of Functions defined within it.

]Along with the Functions even Classes, Constants can also be defined in it.

]Each Function or class or Constants can be referred separately whenever required.

]It is not necessary to use all the Functions within the Module.

]This is applicable to both User defined and System defined Modules

]Few functions like input(), print(), type() are available without importing any module, these are Built in Functions that comes along with the language itself.

 

When Python environment is loaded few default modules are also loaded, which we need not import explicitly. These functions are available in "builtins" module. To view the Functions available in builtins, the procedure is , in the Interpreter prompt of Python type.

 

import builtins

 

and press enter, then type

 

dir(builtins)

 

this will list out the names of the default functions , methods, constants and classes available in the module "builtins". To know the syntax of any function under a module use HELP function. In the interpreter type,

 

help (<function name>)

 

Example

>>> help(object)

Help on class object in module __builtin__:

 

class object

 |  The most base type

 

eg. help(print). To list out the System defined Modules available, in the interpreter tupe

 

>>> help("modules")

 

Please wait a moment while I gather a list of all available modules...

 

AutoComplete        _sqlite3            hashlib             riding

AutoCompleteWindow  _sre                heapq               rith

AutoExpand          _ssl                hello               rithish

BankAccount         _strptime           hi                  rithishkumar

BaseHTTPServer      _struct             hmac                rk

Bastion             _subprocess         hotshot             rlcompleter

Bindings            _symtable           htmlentitydefs      robotparser

CGIHTTPServer       _testcapi           htmllib             rpc

CSC                 _threading_local    httplib             rs

CallTipWindow       _tkinter            idle                rss

CallTips            _warnings           idlelib             rsss

Canvas              _weakref            idlever             rssss

ClassBrowser        _weakrefset         if                  run

CodeContext         _winreg             ifelseif            runpy

ColorDelegator      abc                 ihooks              sample

ConfigParser        aboutDialog         imageop             sched

Cookie              aifc                imaplib             select

Danusrii            amount              imghdr              sets

Debugger            antigravity         imp                 sgmllib

Delegator           anuuuuuuuu          importlib           sha

Dialog              anuuuuuuuuuuuuuuuu  imputil             shelve

DocXMLRPCServer     anydbm              inspect             shlex

EditorWindow        argparse            io                  shutil

Enter               array               ish                 signal

FileDialog          ast                 itertools           site

FileList            asynchat            jj                  smtpd

FixTk               asyncore            jojo                smtplib

FormatParagraph     atexit              json                sndhdr

GrepDialog          audiodev            keybindingDialog    socket

HTMLParser          audioop             keyword             sql

HyperParser         base64              kum                 sqlite3

IOBinding           bdb                 kumar               squares

IdleHistory         binascii            kutti               sre

MimeWriter          binhex              lib2to3             sre_compile

MultiCall           bisect              linecache           sre_constants

MultiStatusBar      break               listttt             sre_parse

ObjectBrowser       bsddb               locale              ssl

OutputWindow        bye                 logging             stat

ParenMatch          bz2                 macosxSupport       statvfs

PathBrowser         cPickle             macpath             string

Percolator          cProfile            macurl2path         stringold

PyParse             cStringIO           mailbox             stringprep

PyShell             calendar            mailcap             strop

Queue               cgi                 markupbase          struct

RemoteDebugger      cgitb               marshal             student

RemoteObjectBrowser chunk               math                subprocess

ReplaceDialog       cmath               md5                 sunau

RstripExtension     cmd                 membership          sunaudio

ScriptBinding       code                mhlib               symbol

ScrolledList        codecs              mimetools           symtable

ScrolledText        codeop              mimetypes           synchronizing

SearchDialog        collections         mimify              sys

SearchDialogBase    colorsys            mmap                sysconfig

SearchEngine        commands            mmm                 t

SimpleDialog        compileall          modulefinder        tabbedpages

SimpleHTTPServer    compiler            msilib              tabnanny

SimpleXMLRPCServer  configDialog        msvcrt              tarfile

SocketServer        configHandler       multifile           telnetlib

StackViewer         configHelpSourceEdit multilevel inheri   tempfile

StringIO            configSectionNameDialog multiprocessing     test

Tix                 contextlib          multithread         testcode

Tkconstants         continue            mutex               textView

Tkdnd               cookielib           naveen              textwrap

Tkinter             copy                nestedif            thalapathi

ToolTip             copy_reg            netrc               this

TreeWidget          csv                 new                 thread

UndoDelegator       ctypes              nnnkkk              threading

UserDict            curses              nntplib             threadmodule

UserList            data                nt                  time

UserString          datetime            ntpath              timeit

WidgetRedirector    dbhash              nturl2path          tkColorChooser

WindowList          decimal             numbers             tkCommonDialog

ZoomHeight          dh                  oneg                tkFileDialog

_LWPCookieJar       difflib             op                  tkFont

_MozillaCookieJar   dircache            opcode              tkMessageBox

__builtin__         dis                 operator            tkSimpleDialog

__future__          distutils           operator overloading toaiff

_abcoll             doctest             optparse            token

_ast                dumbdbm             os                  tokenize

_bisect             dummy_thread        os2emxpath          tony

_bsddb              dummy_threading     p                   trace

_codecs             dynOptionMenuWidget parser              traceback

_codecs_cn          email               pdb                 ttk

_codecs_hk          employee            pickle              tty

_codecs_iso2022     encodings           pickletools         turtle

_codecs_jp          errno               pipes               types

_codecs_kr          example1            pkgutil             unicodedata

_codecs_tw          exceptions          platform            unittest

_collections        fgg                 plistlib            urllib

_csv                fhgj                pocm                urllib2

_ctypes             filecmp             pocm1               urlparse

_ctypes_test        fileinput           pocm2               user

_elementtree        fnmatch             popen2              uu

_functools          fo                  poplib              uuid

_hashlib            fooorrrr            posixfile           warnings

_heapq              formatter           posixpath           wave

_hotshot            fpformat            pprint              weakref

_io                 fractions           profile             webbrowser

_json               ftplib              pstats              whichdb

_locale             fun                 pty                 winsound

_lsprof             functools           py_compile          wsgiref

_md5                future_builtins     pyclbr              xdrlib

_msi                gc                  pydoc               xml

_multibytecodec     genericpath         pydoc_data          xmllib

_multiprocessing    getopt              pyexpat             xmlrpclib

_osx_support        getpass             quopri              xxsubtype

_pyio               gettext             r                   zipfile

_random             gg                  random              zipimport

_sha                glob                re                  zlib

_sha256             greatesvalue        repr               

_sha512             gzip                rexec              

_socket             h                   rfc822              

 

Enter any module name to get more help.  Or, type "modules spam" to search

for modules whose descriptions contain the word "spam".

 

>>> 

 

we will get a display of Module Names in alphabetical order. While the DIR function lists out the Functions available in the loaded Module. The HELP function lists out the Syntax of a particular Function

 

Packages

 

While Modules are equivalent to Files in a System, The Packages are equivalent to Folders. Therefore referring any Function that is available in a Package, will be like

 

<package name>.<module name>.<function name>

 

Using FROM statement

 

To avoid writing such lengthy part of Package, Module and Function name each time , we can use the From statement.

 

Syntax

 

from <Module name> import <function name>

 

If only a particular function is going to be used within our program, then we can just use

 

import < Module name >.<function name>

 

Both helps to refer a Function without referring the Module names or Package Names during usage. Just reference of Function name is enough, when a Module is imported. But good programming practice is to include the Module name also to avoid any clash of same Function names in different Modules are already discussed.

 

Using alias name for /modules in Import Statement

 

Instead of using the lengthy module name. function name each time we refer, it is possible to use Alias where we can replace the modulename.functionname with the aliasname.

 

Syntax

import <module name> as <alias name>

 

Example

 

import module1 as M

 

Whenever we have to refer the Module1,we can use the alias M instead. This is even applicable to the Functions within the module.