PHP supports the concept of variable functions. This means that if
a variable name has parentheses appended to it, PHP will look for
a function with the same name as whatever the variable evaluates
to, and will attempt to execute it. Among other things, this can
be used to implement callbacks, function tables, and so forth.
Variable functions won't work with language constructs such
as echo(), print(),
unset(), isset(),
empty(), include(),
require() and the like. You need to use
your own wrapper function to utilize any of these constructs
as variable functions.
Example 12-13. Variable function example |
<?php
function foo() {
echo "In foo()<br />\n";
}
function bar($arg = '')
{
echo "In bar(); argument was '$arg'.<br />\n";
}
function echoit($string)
{
echo $string;
}
$func = 'foo';
$func(); $func = 'bar';
$func('test'); $func = 'echoit';
$func('test'); ?>
|
|
You can also call an object's method by using the variable functions
feature.
Example 12-14. Variable method example |
<?php
class Foo
{
function Variable()
{
$name = 'Bar';
$this->$name(); }
function Bar()
{
echo "This is Bar";
}
}
$foo = new Foo();
$funcname = "Variable";
$foo->$funcname(); ?>
|
|
See also call_user_func(),
variable variables and function_exists().
