Why can't SplFileInfo be converted to boolean?

Question

One of the limitations of PHP is that objects always evaluate to true. However SplFileinfo (and subclasses such as Symfony's UploadedFile) behave differently:

$a = new ArrayIterator();       // or any other class
$b = new SplFileInfo(__FILE__); // file used is not important

if ($a) echo 'true';   // 'true'
if (!$a) echo 'false'; // nothing because $a is true

if ($b) echo 'true';   // 'true'
if (!$b) echo 'false'; // Catchable fatal error: Object of class 
                       // SplFileInfo could not be converted to boolean

Is this a bug? Tested in 5.3 and 5.4. Also happens with SplFileObject. Possible related question. And a Symfony issue from 2011.

Interrupter

Answer 1

I feel it's a bug so I filed a bug report.

https://bugs.php.net/bug.php?id=65213

-- Edit, somewhere roughly around php 5.6.17 this bug seems to have been fixed.

Landloper

And someone else thinks it's a feature ;-) – Interrupter

Answer 2

I came across this issue as well. I don't know what PHP's rational for this exception is.

For anyone else coming across this, an easy workaround is just to compare the SplFileInfo object to false.

$b = new SplFileInfo(__FILE__);
if ($b != false) {
   echo "This will not throw an exception";
}

if (!$b) {
   echo "This will throw an exception";
}

Capacious