XLII. Function Handling Functions


These functions all handle various operations involved in working with functions.




本函数库作为 PHP 内核的一部分,不用安装就能使用。


本扩展模块在 php.ini 中未定义任何配置选项。



call_user_func_array --  Call a user function given with an array of parameters
call_user_func --  Call a user function given by the first parameter
create_function -- Create an anonymous (lambda-style) function
func_get_arg -- Return an item from the argument list
func_get_args --  Returns an array comprising a function's argument list
func_num_args --  Returns the number of arguments passed to the function
function_exists --  Return TRUE if the given function has been defined
get_defined_functions --  Returns an array of all defined functions
register_shutdown_function --  Register a function for execution on shutdown
register_tick_function --  Register a function for execution on each tick
unregister_tick_function --  De-register a function for execution on each tick

add a note add a note User Contributed Notes
Michael T. McGrew
13-May-2005 12:56
An interesting way to use functions is by putting other things than PHP in them, i.e. HTML CSS. This can be useful if you will be using a format for many pages. Yes, the include function can be used also, but by defining them in functions can make them more portable in a way and keep you from having to make many include files. You could use include() when one will be putting big portions of PHP, HTML, and/or CSS and will be using them in many pages. Then you could use PHP, HTML, and/or CSS in a function when it is smaller portions of code and only want it to be on a few pages.

I have been using include() for HTML and CSS in my early days of PHP coding, but I will be using functions for that a lot more now.

<?php function a() {  ?>
<style type="text/css">
table {
border: 1px dashed black;
background: #95EAFE;
.linkbar {
<?php ?>

Now doing:
<?php a(); ?>
will return all of the CSS just as if you had wrote it on the actual page, or used include() . The same thing goes for HTML code inside a function. The possibilities are endless...
michael dot bommarito at gmail dot com
31-Jan-2005 03:28
I've developed an easy-to-use hack using these functions to emulate overloaded functions.  It's especially handy for constructors and/or C++ style templating.

Here's a little example to get you going.  This does the trick for most circumstances, and if you need more intelligent parsing, it's not too hard to implement with regex or a more suitable classification scheme.

N.B. Note the lack of whitespace between variable types in case strings.

class Matrix {


function Matrix() {
  $args = func_get_args();
  $argmatch = implode(",", array_map('gettype', $args));

  switch( $argmatch ) {
   case 'integer,integer':
     //initialize m x n matrix

   case 'integer,integer,integer':
     //initialize m x n matrix with constant c

   case 'integer,integer,float':
     //initialize m x n matrix with constant c

   case 'array':
     //initialize from array (2D....)

   case 'array,integer':
     //intialize from array (1D packed with m rows)
     //(void) overload?
     //error handling?


php-note-2003-june-18 at ryandesign dot com
18-Jun-2003 11:22
Xavier's example is rather complicated, and his task would be much more simply accomplished by using classes. Define a base class to do the basic functions open, dump, and close, and create extension classes to override whatever behavior.

class foo {
  function open() {
   // Default functionality for open()
  function dump() {
   // Default functionality for dump()
  function close() {
   // Default functionality for close()

class bar extends foo {
  function open() {
   // Override functionality of open()
  // dump() and close() remain as in class foo
xmontero at dsitelecom dot com
24-Aug-2002 05:49
You can do some kind of overloading functions in PHP using "function_exists".

Let's suppose you want a script to call plugins that are php files and you want the plugins to "override" behaviours that if not overriden are used by default.

You might for example write a "mySQL table viewer" which displays a table and it "opens a table", "dumps the header", "dumps row-by-row" and then "closes the table".

Let's suppose you want a plugin for "Stocks" which prints negative stocks in red, so you want to override the "dumping row-by-row" to do that behaviour. Instead you do not want to have all the "default behaviour" repeated in the plugin.

You may then do the following:

1) Define a default plugin (ex: "default.php"

2) Write all your functions in default.php to open, dump and close, but add them a suffix:


3) Call your functions with a wrapper: Insetad of this:
open_table() or open_table_default() write this:


4) Then write a function called plugincall which uses function_exists() to see if you call one or the other function:

function plugincall($desired_function_name)

if( function_exists( $desired_function_name))
   //Call the plugin
   //Note the $ before the name
  $desired_function_name = $desired_function_name . "_default";
  if( function_exists($desired_function_name))
     //Call the default
     //Note the $ before the name
     // Nor the plugin nor the default were defined

So, now, if the require_once(plugin.php) contains a function called "open_table()", it will be used. Instaed, "open_table_default()" will be used.

It's not like overloading functions, but it is very useful to write scripts ampliable by other programmers: If they write a function, it is used, if not, the default is used.

See ya!
Xavier Montero.