Best way to give a variable a default value (simulate Perl ||, ||= )

Question

I love doing this sort of thing in Perl: $foo = $bar || $baz to assign $baz to $foo if $bar is empty or undefined. You al

Answer 1

In PHP 7 we finally have a way to do this elegantly. It is called the Null coalescing operator. You can use it like this:

$name = $_GET['name'] ?? 'john doe';

This is equivalent to

$name = isset($_GET['name']) ? $_GET['name']:'john doe';

Answer 2

PHP 5.3 has a shorthand ?: operator:

$foo = $bar ?: $baz;

Which assigns $bar if it's not an empty value (I don't know how this would be different in PHP from Perl), otherwise $baz, and is the same as this in Perl and older versions of PHP:

$foo = $bar ? $bar : $baz;

But PHP does not have a compound assignment operator for this (that is, no equivalent of Perl's ||=).

Also, PHP will make noise if $bar isn't set unless you turn notices off. There is also a semantic difference between isset() and empty(). The former returns false if the variable doesn't exist, or is set to NULL. The latter returns true if it doesn't exist, or is set to 0, '', false or NULL.