(PHP 8)
The Stringable interface denotes a class as having a __toString() method. Unlike most interfaces, Stringable is implicitly present on any class that has the magic __toString() method defined, although it can and should be declared explicitly.
Its primary value is to allow functions to type check against the union
type string|Stringable to accept either a string primitive
or an object that can be cast to a string.
Example #1 Basic Stringable Usage
<?php
class IPv4Address implements Stringable {
public function __construct(
private string $oct1,
private string $oct2,
private string $oct3,
private string $oct4,
) {}
public function __toString(): string {
return "$this->oct1.$this->oct2.$this->oct3.$this->oct4";
}
}
function showStuff(string|Stringable $value) {
// For a Stringable, this will implicitliy call __toString().
print $value;
}
$ip = new IPv4Address('123', '234', '42', '9');
showStuff($ip);
?>The above example will output something similar to:
123.234.42.9
Since it's introduced in PHP 8, IPv4Address class Example #1 could be shortened to:
<?php
class IPv4Address implements Stringable {
public function __construct(private string $oct1, private string $oct2, private string $oct3, private string $oct4) {
}
public function __toString(): string {
return "$this->oct1.$this->oct2.$this->oct3.$this->oct4";
}
}
?>