PHP OOP中$ a =&$ b,$ a = $ b和$ a = clone $ b之间的差异

Question

是什么区别$a = &$b,$a = $b并且$b = clone $a在PHP OOP？$a是一个类的实例.

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; 

并使用References,Object Cloning查看更多信息.