Source

File: wp-includes/class-requests.php

protected static function get_transport($capabilities = array()) {
		// Caching code, don't bother testing coverage
		// @codeCoverageIgnoreStart
		// array of capabilities as a string to be used as an array key
		ksort($capabilities);
		$cap_string = serialize($capabilities);

		// Don't search for a transport if it's already been done for these $capabilities
		if (isset(self::$transport[$cap_string]) && self::$transport[$cap_string] !== null) {
			$class = self::$transport[$cap_string];
			return new $class();
		}
		// @codeCoverageIgnoreEnd

		if (empty(self::$transports)) {
			self::$transports = array(
				'Requests_Transport_cURL',
				'Requests_Transport_fsockopen',
			);
		}

		// Find us a working transport
		foreach (self::$transports as $class) {
			if (!class_exists($class)) {
				continue;
			}

			$result = call_user_func(array($class, 'test'), $capabilities);
			if ($result) {
				self::$transport[$cap_string] = $class;
				break;
			}
		}
		if (self::$transport[$cap_string] === null) {
			throw new Requests_Exception('No working transports found', 'notransport', self::$transports);
		}

		$class = self::$transport[$cap_string];
		return new $class();
	}