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Serializable::serialize

(PHP 5 >= 5.1.0, PHP 7)

Serializable::serializeオブジェクトの文字列表現

説明

abstract public string Serializable::serialize ( void )

オブジェクトを文字列であらわしたものを返します。

注意:

このメソッドは、オブジェクトの デストラクタ として働きます。 このメソッドの後に __destruct() メソッドがコールされることは ありません。 method.

パラメータ

この関数にはパラメータはありません。

返り値

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。

参考

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User Contributed Notes 2 notes

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18
crog at gustavus dot edu
4 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.
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2
John
8 months 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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