如何在PHP 7.x中强制转换匿名类？

Question

I wondered if there was a way to type the return of a method that instantiates an anonymous class?

php

public function getApi() // <-- type ?
{
    $api = $this->api ?: [];
    return new class ($api)
    {
        private $key, $validTill;
        public function __construct(array $api)
        {
            $this->key       = array_key_exists('key', $api) ? $api['key'] : null;
            $this->validTill = array_key_exists('validTill', $api) ? $api['validTill'] : null;
        }
        public function getKey():?string
        {
            return $this->key;
        }
        public function getValidTill(): ?string
        {
            return $this->validTill;
        }
    };
}

Answer 1

If you're concerned about the type, or behavior, of the returned class, you really should define an interface for this:

interface KeyInterface 
{
    public function getKey(): ?string;
    public function getValidTill(): ?string;
}

Then have the anonymous class implement the interface:

public function getApi(): KeyInterface
{
    $api = $this->api ?: [];
    return new class ($api) implements KeyInterface
    ...
}

Anonymous classes can still implement interfaces and inherit from other classes.