I'm working on a new project and I've come upon the question if the ternary short hand operator the same as using the traditional ternary in combination with the empty() function?
For clarity purposes my question is if: $a ?: $b is the same as !empty($a) ? $a : $b ?
$a ?: $b is short-hand for $a ? $a : $b which is not quite the same as !empty($a) ? $a : $b
The difference between them requires careful reading of the definition of the empty pseudo-function:
Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals false. empty() does not generate a warning if the variable does not exist.
When you just use $a "in boolean context", as in if ( $a ) or $a ? $a : $b or $a ?: $b, its value will be converted to boolean. If the variable doesn't exist - a mistyped variable name, for instance - a Warning will be issued while retrieving that value.
The special power of the empty() pseudo-function is that it won't give you that Warning. The actual result will be the same - an unset variable is considered "equal to false" - but the two pieces of code aren't always interchangeable.