I was diving into Symfony framework (version 4) code and found this piece of code:
$env = $_SERVER['APP_ENV'] ?? 'dev';
I’m not sure what this actually does but I imagine that it expands to something like:
$env = $_SERVER['APP_ENV'] != null ? $_SERVER['APP_ENV'] : 'dev';
Or maybe:
$env = isset($_SERVER['APP_ENV']) ? $_SERVER['APP_ENV'] : 'dev';
Does someone have any precision about the subject?