PHP Ternary Operator checking if variable contains something?

Question

Consider the following (simplified to the bare bones):

abstract class Validator {    

    public function __construct($data = null)
    {
        $this->data = $data ?: Input::all();
    }
}


$validation = new PageValidator($data);

'Input::all' is returning an array. $data is also an array.

The bit I am struggling with is:

$this->data = $data ?: Input::all();

I think it is essentially doing this:

    if(!$data) {
        $this->data = Input::all();
    } else {
        $this->data = $data;
    };

But I don't really understand how?

Answer 1

It's a feature of PHP 5.3 and above:

The ternary operator now has a shorthand form: ?:.

Answer 2

Your understanding of the ternary operator is correct.

The exact syntax you've shown that omits the middle part of the operator was a feature added in PHP 5.3:

Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.

The full expression, without omission, is:

$this->data = $data ? $data : Input::all();

Which translates to what you've assumed:

if($data) {
    $this->data = $data;
} else {
    $this->data = Input::all();
}