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Php functions.variable functions () function

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Variable functions

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 17-14. Variable function example

<?php
function foo() {
    echo
"In foo()<br />\n";
}

function
bar($arg = '')
{
    echo
"In bar(); argument was '$arg'.<br />\n";
}

// This is a wrapper function around echo
function echoit($string)
{
    echo
$string;
}

$func = 'foo';
$func();        // This calls foo()

$func = 'bar';
$func('test');  // This calls bar()

$func = 'echoit';
$func('test');  // This calls echoit()
?>

You can also call an object's method by using the variable functions feature.

Example 17-15. Variable method example

<?php
class Foo
{
    function
Variable()
    {
        
$name = 'Bar';
        
$this->$name(); // This calls the Bar() method
    
}
    
    function
Bar()
    {
        echo
"This is Bar";
    }
}

$foo = new Foo();
$funcname = "Variable";
$foo->$funcname();  // This calls $foo->Variable()

?>

See also call_user_func(), variable variables and function_exists().

Php functions.variable functions Function syntax tag

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Php functions.variable functions syntax tutorial

php tutorial guide and code design are for easy learning and programming. The code practice section provided at the top is for practising of this syntax. Use the code section up to practice your php programming online. Learning php is very easy, all you need is to use the examples on this site and practice them to perfect your skills.


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