喜欢 Rust 的风格，写一个 PHP 的 Option 类

[HowToMakeLove]

第一次分享东西

项目地址： https://github.com/lisqorz/option

除了这些，其实还想在里面加上 PHP 的 标准库方法，这样就可以更加函数式了

小例子

case 1

// Option
$res = Some($db->get())->expect(new \Exception("msg"));

// native
$res = $db->get();
if (is_null($res)) {
    throw new \Exception("msg");
}

case2

// Option
$_POST["hello"] = null;
Some($_POST['hello'])->unwrapOr("hi"); // hi
$_POST["hello"] = "hello";
Some($_POST['hello'])->unwrapOr("hi"); // hello

// ... but we have $_POST["hello"]??"hi" 2333

Case3

// scenario
$obj = new Obj();
$obj->attr = null; // attr is Object;

// Option

// None
$attr = Some($obj->attr)->andThen(function($attr){
	return "";
})->unwrapOr("no success");

//Some
$attr = Some(1)->andThen(function($attr){
    return null;
})->unwrapOr("no success");

// native
$attr = "no success";
if ($obj->attr) {
   $attr = (function($attr){return ""; })()
}
if (!$attr) {
    $attr = "no success";
}

添加一个小例子，并不是用来声明Option有多好，而是想分享一下想法,如果有其它想法，可以一起延伸、讨论 case 0

Native
try {
    $pdo = new PDO($db['dsn'], $db['username'], $db['password'], $options);
} catch (PDOException $e) {
    throw new PDOException('数据库连接失败:' . $e->getMessage());
}

Option
/** @var PDO $conn */
Some(!$pdo->errorCode())->expect(new PDOException("数据库链接失败" . $pdo->errorCode()));

Native
$statement = $pdo->query("select count(id) from link");
$cnt = 0;
if (!$statement) {
    $cnt = $statement->rowCount();
}

Option
$cnt = Some($pdo->query("select count(id) from link"))->andThen(function ($statement) {
    return $statement->rowCount();
})->unwrapOr(0);

print_r($cnt);

Native
$query = $pdo->query("select id,name from link");
$result = [];

if ($query) {
    $res = $query->fetchAll();
    if ($res) {
        foreach ($res as $key => $item) {
            $result[] = [
                "link_id" => $item["id"],
                "link_name" => $item["name"] ?? "匿名链接",
            ];
        }
    }
}

Option
$result = Some($pdo->query("select id,name from link"))->andThen(function ($state) {
    return $state->fetchAll();
})->filter(function ($item) {
    return [
        "link_id" => $item["id"],
        "link_name" => Some($item["name"])->unwrapOr("匿名链接"),
    ];
})->unwrapOr([]);

print_r($result);

[AngelCriss]

啥叫函数式？