PHP Russia 2022

The Stringable interface

(PHP 8)

简介

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.

接口摘要

interface Stringable {
/* 方法 */
}

Stringable Examples

示例 #1 Basic Stringable Usage

<?php
class IPv4Address implements Stringable {
    private 
string $oct1;
    private 
string $oct2;
    private 
string $oct3;
    private 
string $oct4;

    public function 
__construct(string $oct1string $oct2string $oct3string $oct4) {
        
$this->oct1 $oct1;
        
$this->oct2 $oct2;
        
$this->oct3 $oct3;
        
$this->oct4 $oct4;
    }

    public function 
__toString(): string {
        return 
"$this->oct1.$this->oct2.$this->oct3.$this->oct4";
    }
}

function 
showStuff(string|Stringable $value) {
    
// A Stringable will get converted to a string here by calling
    // __toString.
    
print $value;
}

$ip = new IPv4Address('123''234''42''9');

showStuff($ip);
?>

以上例程的输出类似于:

123.234.42.9

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