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Functions and commands with dangerous names

There are some words that we use in our day to day programming life that seem a little scarey and inappropriate to their real task ... and sometimes those words worry trainees on our courses. Examples:

PHP's reset function. It's name seems to threaten to clear our data from somewhere, but all it does is reset a pointer so that following calls to iterators such as each start at the beginning.

global declarations in Tcl and PHP. They seem to imply that a variable is going to be seen everywhere; all they really mean is that a variable in the current procedure or function is shared with the main code (the code not within any procedure or function) of the current application.

And the grandaddy of them all - Unix and Linux's kill command. I'm happy to report that killing is not necessarily fatal, as all it does is send a signal to a specified process. If that process has been written in such a way that it exits, then (yes) it dies ... but if it's been written to perform in another way when it gets an external signal, that's what it does.
(written 2005-08-11, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
A161 - Web Application Deployment - Users and Groups
  [4045] Linux Web Server - User Roles, User Accounts, and shared administration - (2013-03-16)
  [2639] su or su - ... what is the difference? - (2010-02-17)
  [2491] Root is root for a reason! - (2009-11-03)
  [2301] Mistaken identity? - (2009-07-22)
  [2203] Always use su with minus. And where do programs come from? - (2009-05-27)
  [2117] Choosing a railway station fairly in PHP - (2009-04-04)
  [2103] Ask the Tutor - Open Source forum - (2009-03-25)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [1902] sstrwxrwxrwx - Unix and Linux file permissions - (2008-11-23)
  [1773] The Longest Possible Day - (2008-08-26)
  [1650] Looking for files with certain characteristics (Linux / Unix) - (2008-05-22)
  [1619] User and Group settings for Apache httpd web server - (2008-04-22)
  [1592] Setting up a new user - Linux or Unix - (2008-03-26)
  [683] Supporting users on Linux and Unix - (2006-04-13)
  [431] File permissions of Linux and Unix systems - (2005-08-31)

H105 - PHP - Functions
  [3026] Coding efficiency - do not repeat yourself! - (2010-11-02)
  [2929] Passing a variable number of parameters in to a function / method - (2010-08-20)
  [2737] Improving your function calls (APIs) - General and PHP - (2010-04-24)
  [2682] Adding extensions to PHP Open Source applications - callbacks - (2010-03-17)
  [2630] Static variables and ampersands in PHP - (2010-02-10)
  [2488] A variable number of arguments in a PHP function - (2009-11-02)
  [1784] Global - Tcl, PHP, Python - (2008-09-03)
  [1380] Static variables in PHP - (2007-10-05)
  [1357] Clean my plate, but keep my wine bottle. (PHP; Static) - (2007-09-18)
  [1267] is there a lookup function in php? - (2007-07-15)
  [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)
  [1021] PHP - static declaration - (2007-01-04)
  [936] Global, Superglobal, Session variables - scope and persistance in PHP - (2006-11-21)
  [866] A lazy programmer is a good programmer - (2006-09-15)
  [775] Do not duplicate your code - (2006-06-23)
  [421] Don't repeat code - use loops or functions - (2005-08-21)
  [340] Code and code maintainance efficiency - (2005-06-08)
  [339] Passing information into and out of PHP functions - (2005-06-07)
  [308] Call by name v call by value - (2005-05-11)
  [223] There is a function in PHP to do that - (2005-02-21)
  [96] Variable Scope - (2004-10-22)

H106 - PHP - Arrays
  [4244] Disambiguation - PHP List - (2014-03-07)
  [4072] Splitting the difference with PHP - (2013-04-27)
  [4068] Arrays in PHP - contain different and even mixed data types - (2013-04-24)
  [3534] Learning to program in PHP - Regular Expression and Associative Array examples - (2011-12-01)
  [3379] Sorting data the way YOU want it sorted - (2011-08-05)
  [3004] Increment operators for counting - Perl, PHP, C and others - (2010-10-18)
  [2920] Sorting - naturally, or into a different order - (2010-08-14)
  [2915] Looking up a value by key - associative arrays / Hashes / Dictionaries - (2010-08-11)
  [2274] PHP preg functions - examples and comparision - (2009-07-08)
  [2215] If nothing, make it nothing. - (2009-06-02)
  [1614] When an array is not an array - (2008-04-17)
  [1451] More PHP sample and demonstration programs - (2007-12-01)
  [1199] Testing for one of a list of values. - (2007-05-22)
  [1116] PHP adding arrays / summing arrays - (2007-03-23)
  [832] Displaying data at 5 items per line on a web page - (2006-08-14)
  [773] Breaking bread - (2006-06-22)
  [603] PHP - setting sort order with an associative array - (2006-02-13)

T207 - Tcl/Tk - Procedures and Variable Scope
  [3629] Sharing lots of values in Tcl without having lots of global declarations - (2012-02-28)
  [3414] Passing back multiple results in Tcl - upvar and uplevel - (2011-09-01)
  [3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04)
  [2520] Global and Enable - two misused words! - (2009-11-30)
  [2476] Tcl - uplevel to run code at calling level - (2009-10-24)
  [2466] Tcl - passing arrays and strings in and back out of procs - (2009-10-22)
  [1782] Calling procs in Tcl and how it compares to Perl - (2008-09-02)
  [1404] Tcl - global, upvar and uplevel. - (2007-10-24)
  [122] Passing arrays to procs in Tcl - (2004-11-18)


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Reading a news or blog feed (RSS) in your PHP page
Some other Articles
Save the train
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Reading a news or blog feed (RSS) in your PHP page
Functions and commands with dangerous names
Can an older person learn a programming language
Theft of training material
Assignment, equality and identity in PHP
Horse's Mouth is a year old
How to check that a string contains a number in Tcl
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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