Always Typehint

PHP allows the use of <classname>, array or callable, to type the incoming arguments as, respectively, objects of the class <classname>, arrays or callable functions.

When possible, typehint may be used in methods signatures so as to enforce a simple validation for arguments. Typehints are used by PHP, IDE and some tools to check that arguments are of the expected shape.

Typehint may be classes or interfaces.

Whenever possible, typehint should be used so as to give more information about the incoming values. This will be used by PHP compiler and binary to check variables and, eventually, emits catchable exceptions when they are not.

It is recommended to always set the typehint.

Rule Details

This rule is aimed at encouraging the use of typehint.

The following patterns are considered warnings:

<?php

function foo($a) {
	// $a should be typehinted with some class that support `callMethod` method.
	$a->callMethod();
}
?>

The following patterns are not considered ambiguous:

<?php

function foo($a) {
	$b = $a . 1; // $a could be a string or an object that suport __toString()
}

function bar($a, $b) {
	$c = $a + 1; // $a could be a number or an array
}
?>

The following patterns are not considered warnings:

<?php

function foo($a) {
	$b = $a + 1; // $a should be an integer
	$c = $a * 1.2; // $a should be an real
}

?>