Doc #76411 [Com]: Should state that function arguments are passed by reference if objects
Edit report at https://bugs.php.net/bug.php?id=76411&edit=1
ID: 76411
Comment by: a at b dot c dot de
Reported by: teo8976 at gmail dot com
Summary: Should state that function arguments are passed by
reference if objects
Status: Open
Type: Documentation Problem
Package: Documentation problem
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
The line on the Assignment Operators page is the faulty one.
Assignment of objects is by value as well (an object's value is the object itself*; that value
is the one that is assigned).
What assignment does not do is create a new object with the same properties as the object being
assigned (that's what clone is for).
* Which is why objects are said to be passed by value to functions. Since the value of an object is
the object itself, changing the passed object's properties changes the passed object's
properties.
Previous Comments:
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[2018-06-03 21:49:51] requinix@php.net
The "objects are passed by reference" statement is directly addressed in the OOP docs.
http://php.net/manual/en/language.oop5.references.php
> One of the key-points of PHP 5 OOP that is often mentioned is that "objects are passed by
> references by default".
> This is not completely true. This section rectifies that general thought using some examples.
The terms "by value" and "by reference" refer to the concept of value-types and
reference-types.
https://en.wikipedia.org/wiki/Value_type
https://en.wikipedia.org/wiki/Reference_type
Those terms are being used correctly, but because PHP also has references the "by
reference" is ambiguous.
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[2018-06-03 21:30:06] cmb@php.net
> it should say that an exception to this are objects, which are
> passed by reference.
Note, though, that this would still be misleading. Consider
function foo($object) {
$object = null;
}
vs.
function foo(&$object) {
$object = null;
}
Only the latter has an effect which can be observed outside the
function; see <https://3v4l.org/04vX5>.
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[2018-06-03 18:56:27] teo8976 at gmail dot com
Description:
------------
---
From manual page: http://www.php.net/functions.arguments
---
Where it says:
"""
By default, function arguments are passed by value (so that if the value of the argument within the
function is changed, it does not get changed outside of the function).
"""
it should say that an exception to this are objects, which are passed by reference.
For comparison, the documentation for the assignment operator does specify that:
http://docs.php.net/manual/en/language.operators.assignment.php
"""
Note that the assignment copies the original variable to the new one (assignment by value), [...]
An exception to the usual assignment by value behaviour within PHP occurs with objects, which are
assigned by reference
"""
So, the documentation for function arguments should be equally clear and explicit.
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