Are you sure? https://php.net/manual/en/language.types.string.php#language.types.string.parsing https://php.net/manual/en/language.types.string.php#language...

Are you sure? https://php.net/manual/en/language.types.string.php#language.types.string.parsing https://php.net/manual/en/language.types.string.php#language... suggests that it can only interpolate a few specific types of expression, but can't do e.g. arithmetic or or simple function calls. (It seems you can interpolate a variable named by a function call, but you can't interpolate a function call itself.)