Question

我有下一个代码

<?php

interface SimpleInterface
{
    public function method(): self;
}

trait SimpleTrait
{
    public function method(): self
    {
        return $this;
    }
}

class SomeClass implements SimpleInterface
{

    use SimpleTrait;
}

但是PHP指出RenderableTrait->setLayout(layout:string)与RenderableInterface->setLayout(layout: string)不兼容

显然，因为接口期望self作为返回值，但是在特征中我返回Trait本身，并且它不兼容。有什么解决办法吗？

Answer 1

更改返回类型为 SimpleInterface 的 self https://3v4l.org/LTc8E

<?php

trait Test {
    public function test() {
        return $this;
    }
}

class Foo {
    use Test;
}

class Bar {
    use Test;
}

$f = new Foo();
$b = new Bar();
// object(Foo)
var_dump($f->test());
// object(Bar)
var_dump($b->test());

//So for you case
interface SimpleInterface
{
    public function method(): SimpleInterface;
}

trait SimpleTrait
{
    // This method will work only in classes that implements SimpleInterface
    public function method(): SimpleInterface
    {
        return $this;
    }
}

class SomeClass implements SimpleInterface
{
    // Traits $this is now SomeClass
    use SimpleTrait;
}

$s = new SomeClass();
// object(SomeClass)
var_dump($s->method());

接口的PHP特性

1 个答案: