php - PHP OOP での $a=&$b 、 $a = $b 、 $a= clone $b の違い

Question

$a = &$bとPHP OOP$a = $bの違いは何ですか? クラスのインスタンスです。$b = clone $a$a

Answer 1

// $a is a reference of $b, if $a changes, so does $b.    
$a = &$b; 

// assign $b to $a, the most basic assign.
$a = $b; 

// This is for object clone. Assign a copy of object `$b` to `$a`. 
// Without clone, $a and $b has same object id, which means they are pointing to same object.
$a = clone $b; 

References、Object Cloningで詳細を確認してください。

Answer 2

// $a has same object id as $b. if u set $b = NULL, $a would be still an object
$a = $b;

// $a is a link to $b. if u set $b = NULL, $a would also become NULL
$a = &$b;

// clone $b and store to $a. also __clone method of $b will be executed
$a = clone $b;

Answer 3

ZVAL 構造とは何か、ZVAL 構造の refcount,is_ref とは何かを知らなかった場合は、PHP のガベージ コレクションに少し時間をかけてください。