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    Serializable::serialize

    (PHP 5 >= 5.1.0, PHP 7, PHP 8)

    Serializable::serialize — オブジェクトの文字列表現

    説明

    public Serializable::serialize(): ?string

    オブジェクトを文字列であらわしたものを返します。

    パラメータ

    この関数にはパラメータはありません。

    戻り値

    オブジェクトの文字列表現、あるいは null を返します。

    エラー / 例外

    文字列や null 以外の型を返すときに Exception をスローします。

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    User Contributed Notes 2 notes

    up
    20
    crog at gustavus dot edu
    11 years ago
    The documentation here is somewhat misleading. Where it says "This method acts as the destructor of the object. The __destruct() method will not be called after this method," I believe the intent is not that the destructor is not run on the object itself, but that the destructor is not called /as part of the serialization process/.

    That is, the object will still be destructed as it goes out of scope as normal, but the destructor is not called as a part of the object's serialization.
    up
    4
    John
    7 years ago
    I don't like the bad docs here, which are wrongly claiming that "serialize(): This method acts as the destructor of the object. The __destruct() method will not be called after this method.".

    They are simply meaning that serialize() will NOT call __destruct(). That is the ONLY thing they mean.

    Your object that is being serialized will continue to live as a normal object. So you should NOT treat serialize() as your destructor! Treat your object as a still-living copy that the user may be using!

    The destructor will always run as normal, later, when your object goes out of scope (or is forcibly unset() by you)).

    Example with proof:

    <?php

    class A implements Serializable
    {
    public     $data = [];

    public function     __destruct()
    {
    echo     "Destruct of A called.\n";
    }

    public function     serialize()
    {
    printf("- Serialize of %s called.\n", static::class);
    return     serialize($this->data);
    }

    public function     unserialize($serialized)
    {
    printf("- Unserialize of %s called.\n", static::class);
    $this->data = unserialize($serialized);
    }
    }

    class     B extends A
    {
    public function     __destruct()
    {
    echo     "Destruct of B called.\n";
    }
    }

    $a = new A();
    $a->data['inner_b'] = new B();
    var_dump($a);

    echo     "-----------------\n";
    echo     "Calling serialize($a):\n";
    $str = serialize($a);
    echo     "-----------------\n";
    echo     "End of script shutdown from here on:...\n";

    ?>

    Result:

    ```
    object(A)#1 (1) {
    ["data"]=>
    array(1) {
    ["inner_b"]=>
    object(B)#2 (1) {
    ["data"]=>
    array(0) {
    }
    }
    }
    }
    -----------------
    Calling serialize($a):
    - Serialize of A called.
    - Serialize of B called.
    -----------------
    End of script shutdown from here on:...
    Destruct of A called.
    Destruct of B called.
    ```
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