如何在PHP中检查对象是否实现 - > __ toString（）？

Is there anyway to see if an object specifically implements ->__toString? This doesn't seem to work:

反正有没有看到一个对象是否专门实现 - > __ toString?这似乎不起作用:

method_exists($object, '__toString');

4 个解决方案

#1

There are two way to check it.

有两种方法可以检查它。

Lets assume you have classes:

让我们假设您有课程:

class Foo
{
    public function __toString()
    {
        return 'foobar';
    }
}

class Bar
{
}

Then you can do either:

然后你可以做到:

$rc = new ReflectionClass('Foo');       
var_dump($rc->hasMethod('__toString'));

$rc = new ReflectionClass('Bar');       
var_dump($rc->hasMethod('__toString'));

or use:

$fo = new Foo;
var_dump( method_exists($fo , '__toString'));
$ba = new Bar;
var_dump( method_exists($ba , '__toString'));

Difference is that in first case the class is not actually instantiated.
You can look at demo here : http://codepad.viper-7.com/B0EjOK

区别在于,在第一种情况下,该类实际上并未实例化。您可以在这里查看演示:http://codepad.viper-7.com/B0EjOK

#2

I must be doing something wrong somewhere else, because this works:

我必须在其他地方做错事,因为这有效:

class Test {

function __toString() {
    return 'Test';
}

}

$test = new Test();

echo method_exists($test, '__toString');

#3

You should be able to use reflection: http://www.php.net/manual/en/reflectionclass.hasmethod.php

你应该能够使用反射:http://www.php.net/manual/en/reflectionclass.hasmethod.php

#4

Reflections is slow, and I think it's the worst solution to use them.

反思很慢,我认为这是使用它们的最糟糕的解决方案。

bool method_exists ( mixed $object , string $method_name )

object - An object instance or a class name (http://php.net/manual/en/function.method-exists.php)

object - 对象实例或类名(http://php.net/manual/en/function.method-exists.php)

There is no need to create an object to checking for existence of a method.

无需创建对象来检查方法是否存在。

method_exists('foo', '__toString')

interface StringInterface{
   public function __toString() :string;
}


class Foo implement StringInterface {...}

->>(new MyClass) instanceof StringInterface

#1