Although it would be convenient at times to be able to refer to any variable anywhere in your program, this is not how most languages work by default. And they're designed that way! That's to avoid confusion as a program grows, when there's a strong possibility of several programmers on the same project happening to choose the same name to use within their own are (module / function / subroutine). It also makes for cleaner code, as it avoids anyone who's writing or updating the program being tempted to make use of a variable from another area without passing it around properly - i.e. it avoids adding a long distance dependency that will be trouble during code maintenance.
Example in Python -
[here] - from yesterday's
learning to program in Python course.
(written 2012-10-08, updated 2012-10-13)
Associated topics are indexed under
Y105 - Python - Functions, Modules and Packages [4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
[3945] vargs in Python - how to call a method with unknown number of parameters - (2012-12-06)
[3931] Optional positional and named parameters in Python - (2012-11-23)
[3852] Static variables in Python? - (2012-08-29)
[3766] Python timing - when to use a list, and when to use a generator - (2012-06-16)
[3695] Functions are first class variables in Lua and Python - (2012-04-13)
[3662] Finding all the unique lines in a file, using Python or Perl - (2012-03-20)
[3474] Python Packages - groupings of modules. An introduction - (2011-10-11)
[3472] Static variables in functions - and better ways using objects - (2011-10-10)
[3464] Passing optional and named parameters to python methods - (2011-10-04)
[3459] Catching the fishes first? - (2011-09-27)
[3280] Passing parameters to Python functions - the options you have - (2011-05-07)
[3159] Returning multiple values from a function call in various languages - a comparison - (2011-02-06)
[2998] Using an exception to initialise a static variable in a Python function / method - (2010-10-13)
[2994] Python - some common questions answered in code examples - (2010-10-10)
[2929] Passing a variable number of parameters in to a function / method - (2010-08-20)
[2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
[2766] Optional and named parameters to Python functions/methods - (2010-05-15)
[2718] Python - access to variables in the outer scope - (2010-04-12)
[2520] Global and Enable - two misused words! - (2009-11-30)
[2506] Good example of recursion in Python - analyse an RSS feed - (2009-11-18)
[2481] Sample code with errors in it on our web site - (2009-10-29)
[2440] Optional parameters to Python functions - (2009-10-07)
[2439] Multiple returns from a function in Python - (2009-10-06)
[2011] Conversion of OSI grid references to Eastings and Northings - (2009-01-28)
[1879] Dynamic code - Python - (2008-11-11)
[1871] Optional and named parameters in Python - (2008-11-05)
[1870] What to do with a huge crop of apples - (2008-11-04)
[1869] Anonymous functions (lambdas) and map in Python - (2008-11-04)
[1790] Sharing variables with functions, but keeping them local too - Python - (2008-09-09)
[1784] Global - Tcl, PHP, Python - (2008-09-03)
[1464] Python Script - easy examples of lots of basics - (2007-12-08)
[1202] Returning multiple values from a function (Perl, PHP, Python) - (2007-05-24)
[1163] A better alternative to cutting and pasting code - (2007-04-26)
[1134] Function / method parameters with * and ** in Python - (2007-04-04)
[959] It's the 1st, not the 1nd 1rd or 1th. - (2006-12-01)
[949] Sludge off the mountain, and Python and PHP - (2006-11-27)
[913] Python - A list of methods - (2006-11-03)
[912] Recursion in Python - (2006-11-02)
[900] Python - function v method - (2006-10-20)
[821] Dynamic functions and names - Python - (2006-08-03)
[775] Do not duplicate your code - (2006-06-23)
[749] Cottage industry or production line data handling methods - (2006-06-07)
[745] Python modules. The distribution, The Cheese Shop and the Vaults of Parnassus. - (2006-06-05)
[668] Python - block insets help with documentation - (2006-04-04)
[561] Python's Generator functions - (2006-01-11)
[418] Difference between import and from in Python - (2005-08-18)
[386] What is a callback? - (2005-07-22)
[340] Code and code maintainance efficiency - (2005-06-08)
[308] Call by name v call by value - (2005-05-11)
[303] Lambdas in Python - (2005-05-06)
[294] Python generator functions, lambdas, and iterators - (2005-04-28)
[105] Distance Learning - (2004-10-31)
[96] Variable Scope - (2004-10-22)
1b81
Some other Articles
Melksham Chamber of Commerce - whence in 2013 and beyond?What a difference a year made - Melksham CampusInheritance, Composition and Associated objects - when to use which - Python exampleFormatting output - why we need to, and first Python exampleDefault local - a good choice by the author of PythonPictures - across the park, French Weir and River Tone, TauntonApple Pressing Day 2012Community Transport - Pewsey, Taunton, and the whole picture tooWiltshire Public Transport User Group co-ordinationChamber of Commerce - looking forward in Melksham and in Wessex