Why store function as variable in PHP

Why store function as variable in PHP

References

Reference NO 1

http://php.net/manual/en/functions.variable-functions.php

Reference NO 2

http://stackoverflow.com/questions/15188058/why-store-function-as-variable-in-php

Reference NO 3

http://stackoverflow.com/questions/8466473/use-variable-as-function-name-in-php

Reference NO 4

http://forum.oiopublisher.com/discussion/605/php-function-stored-in-a-variable/

Reference NO 5

http://www.1stwebdesigner.com/css/smart-code-php-variables/

Reference NO 6

http://www.webmasterworld.com/forum88/7571.htm

Reference NO 7

http://www.w3schools.com/php/php_variables.asp?output=print

Reference NO 8

http://bytes.com/topic/php/answers/3671-variables-do-not-keep-values-after-leaving-function