Function to set default value of associative array if the key is not present

Question

Is there a function in PHP to set default value of a variable if it is not set ? Some inbuilt function to replace something like:

$myFruit = isset($_REQUEST['myfruit']) ? $_REQUEST['myfruit'] : "apple" ;

Answer 1

PHP kind of has an operator for this (since 5.3 I think) which would compress your example to:

$myFruit = $_REQUEST['myfruit'] ?: "apple";

However, I say "kind of" because it only tests if the first operand evaluates to false, and won't suppress notices if it isn't set. So if (as in your example) it might not be set then your original code is best.

The function analogous to dictionary.get is trivial:

function dget($dict, $key, $default) {
    return isset($dict[$key]) ? $dict[$key] : $default;
}

For clarity, I'd still use your original code.

Edit: The userland implementation #2 of ifsetor() at http://wiki.php.net/rfc/ifsetor is a bit neater than the above function and works with non-arrays too, but has the same caveat that the default expression will always be evaluated even if it's not used:

function ifsetor(&$variable, $default = null) {
    if (isset($variable)) {
        $tmp = $variable;
    } else {
        $tmp = $default;
    }
    return $tmp;
}

Answer 2

As far as i know there exists nothing like this in PHP.

You may implement something like this yourself like

$myVar = "Using a variable as a default value!";

function myFunction($myArgument=null) {
    if($myArgument===null)
        $myArgument = $GLOBALS["myVar"];
    echo $myArgument;
}

// Outputs "Hello World!":
myFunction("Hello World!");
// Outputs "Using a variable as a default value!":
myFunction();
// Outputs the same again:
myFunction(null);
// Outputs "Changing the variable affects the function!":
$myVar = "Changing the variable affects the function!";
myFunction();