PHP will let you change a variable’s type at any moment, and there’s nothing you can do about it. While you can use data structures, argument type declaration, and return type declaration to save a lot of damage, you can still change types.
1 2 3 4 5 6 7 8 9 10 11 12 | <?phpdeclare(strict_types=1);function showTypes(int $number) { echo gettype($number) . "\n"; //integer $number = "string"; echo gettype($number) . "\n"; //string}showTypes(2); |
In order to help this situation a little bit, I’m using the appropriate type comparison operators and functions:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | <?php$number = 1;// OKif ($number > 0) {}// Not OKif (!$number) {}if ($number === '') {}if (strlen($number) > 0) {}$string = 'Lorem ipsum';// OKif ($string === '') {}if (strlen($string) > 0) {}// Not OKif (!$string) {}$list = [];// OKif (count($list) > 0) {}// Not OKif (!$list) {}$bool = false;// OKif (true === $bool) {}if (!$bool) {}// Not OKif ($bool == '') {}$var = null; // if I know a var can be null// OKif (null === $var) {}if (is_null($var)) {}// Not OKif (!$var) {} |
As such, I’m being more specific about the type variables are holding. In clean code it’s faster to see what a variable holds, but in legacy systems you can see a variable hundreds of lines later after declaration, or you can get a value from a function with no return type or DocBlock.
Treat each variable as close as possible to its type.