Reputation: 625
Came across this scenario, which I'm sure is me not understanding something OOP related, but doesn't quite make sense to me.
Why does the following PHP:
$prototype = new stdClass();
$prototype->someProperty = new stdClass();
$prototype->someProperty->value = 0;
$clone1 = clone $prototype;
$clone2 = clone $prototype;
$clone1->someProperty->value = 200;
$clone2->someProperty->value = 100;
print_r($clone1);
print_r($clone2);
Output this:
stdClass Object
(
[someProperty] => stdClass Object
(
[value] => 100
)
)
stdClass Object
(
[someProperty] => stdClass Object
(
[value] => 100
)
)
And not this (as I expected):
stdClass Object
(
[someProperty] => stdClass Object
(
[value] => 100
)
)
stdClass Object
(
[someProperty] => stdClass Object
(
[value] => 200
)
)
I'll bet it's something to do with the nested stdClass() which is going over my head; if I remove the someProperty
property it behaves as I'd expect), but as far as I can see I'm creating new objects and not assigning any references anywhere (either implicitly or as a result of just assigning the variable).
As a side question to this, is creating a nested object like this wrong?
Update
A bit more thinking and, would I be along the right lines thinking that my clones are indeed clones, but both contain a reference to the someProperty
property of $prototype
. So I'd need to do a deep clone?
Upvotes: 0
Views: 409
Reputation: 12776
From TFM:
When an object is cloned, PHP 5 will perform a shallow copy of all of the object's properties. Any properties that are references to other variables, will remain references.
When you do: $prototype->someProperty = new stdClass();
an object of stdClass is created on stack, and a reference to it is assigned to someProperty
. When $prototype
is cloned, the clone's someProperty
references the same object.
Upvotes: 2