#26325 [Opn]: At least a notice when accessing private members in a derived class?

[drm at melp dot nl]

ID: 26325
User updated by: drm at melp dot nl
Reported By: drm at melp dot nl
Status: Open
Bug Type: Feature/Change Request
Operating System: Windows XP
PHP Version: 5.0.0b2 (beta2)
New Comment:

Here's a more explanatory piece of code:
[url]http://gerard.yoursite.nl/php.net/private-members.phps[/url]


Previous Comments:
------------------------------------------------------------------------

[2003-11-19 17:49:24] drm at melp dot nl

Description:
------------
Hi :)

I read in the new features list of Zend Engine 2 that access modifiers
like private/protected are introduced, but something really weird comes
in mind when reading carefully.

Private members are returned _empty_ wheing tried to be accessed from
derived classes. "Intended behaviour", is said. OK, i can live with
that. But even when i turned on notices with error_reporting, nothing
is noticed?

The case grows when looking at the following code sample. This could
produce very weird bugs when writing PHP code (i hope you can see that
;)), so I would like to convince you all to at least implement a Notice
when trying to access (non-defined) private (parent) members?

It would do the coders not using E_ALL no harm :) Please consider this
:)

Reproduce code:
---------------
error_reporting ( E_ALL );
class Test {
private $member;
function __construct () { $this->member = "Test constructor";
}
function __toString () { return "Member contains:
{$this->member}"; }
function getMember () { return $this->member; }
function setMember ( $m ) { $this->member = $m; }
}
class DeriveTest extends Test {
function __construct () { parent::__construct (); }
function __toString () { return "Member contains:
{$this->member}, though getMember() says: " . $this->getMember() ."?";
}
function setMember ( $m ) { $this->member = $m; }
}
$o = new DeriveTest ();
echo $o, '<br>';
$o->setMember ( "a" );
echo $o, '<br>';


Expected result:
----------------
The expected result would be for me:

Notice: undefined member ``DeriveTest::$member'' in ...\test.php on
line 12
Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?

or something of the sort

Actual result:
--------------
The actual result is:

Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?


------------------------------------------------------------------------


--
Edit this bug report at [url]http://bugs.php.net/?id=26325&edit=1[/url]

[abies@php.net]

ID: 26325
Updated by: [email]abies@php.net[/email]
Reported By: drm at melp dot nl
Status: Open
Bug Type: Feature/Change Request
Operating System: Windows XP
PHP Version: 5.0.0b2 (beta2)
New Comment:

Actually, the main issue here is that PHP doesn't give a notice at all
if you access an undefined property, whether it is a private property
in a base class or not.




Previous Comments:
------------------------------------------------------------------------

[2003-11-22 09:05:03] drm at melp dot nl

Excuse me, but you are *totally* missing my point here. You are telling
me things i had already pointed out in the first post.

I'll reduce my feature request to one simple line:

Can *at least* a "notice" be triggered when a private member variable
does not exist but is accessed? And by accessed i do NOT mean
assigned!

You're saying it behaves the same way php4 does, but that's just plain
bs. See the following code in PHP4:

<?
error_reporting ( E_ALL );
class Test {
function getMember () {
return $this->member;
}
}
$t = new Test ();
echo $t->getMember ();
?>

This would yield the following notice:
Notice: Undefined property: member in test.php on line 5

All i'm asking is that some notice of the SAME sort can be implemented
in php5 when trying to access parent private members.

------------------------------------------------------------------------

[2003-11-20 11:46:55] [email]jay@php.net[/email]

There are two issues here.

First, PHP 5 is just acting like PHP 4 did -- you can
initialize a member of an object without explicitly
declaring it in the class definition and PHP won't
complain.

Second, Test::$member and DeriveTest::$member aren't the
same things. Test::$member being private, it's only
accessible and visible from within Test. DeriveTest has no
idea it exists, so it creates its own public member called
$member. If you do a print_r($o) at the end of your
script, you'll see that there are two members called
$member, one of which is private and the other public.

So yes, this is intended behaviour. One of the main ideas
of private members is that they aren't even visible from
derived classes. If you try to access a private member
from a parent class, the derived class won't see it and
will instead try using its own member, and if that doesn't
exist it will implicitly create it.

J

------------------------------------------------------------------------

[2003-11-20 04:45:48] drm at melp dot nl

Here's a more explanatory piece of code:
[url]http://gerard.yoursite.nl/php.net/private-members.phps[/url]

------------------------------------------------------------------------

[2003-11-19 17:49:24] drm at melp dot nl

Description:
------------
Hi :)

I read in the new features list of Zend Engine 2 that access modifiers
like private/protected are introduced, but something really weird comes
in mind when reading carefully.

Private members are returned _empty_ wheing tried to be accessed from
derived classes. "Intended behaviour", is said. OK, i can live with
that. But even when i turned on notices with error_reporting, nothing
is noticed?

The case grows when looking at the following code sample. This could
produce very weird bugs when writing PHP code (i hope you can see that
;)), so I would like to convince you all to at least implement a Notice
when trying to access (non-defined) private (parent) members?

It would do the coders not using E_ALL no harm :) Please consider this
:)

Reproduce code:
---------------
error_reporting ( E_ALL );
class Test {
private $member;
function __construct () { $this->member = "Test constructor";
}
function __toString () { return "Member contains:
{$this->member}"; }
function getMember () { return $this->member; }
function setMember ( $m ) { $this->member = $m; }
}
class DeriveTest extends Test {
function __construct () { parent::__construct (); }
function __toString () { return "Member contains:
{$this->member}, though getMember() says: " . $this->getMember() ."?";
}
function setMember ( $m ) { $this->member = $m; }
}
$o = new DeriveTest ();
echo $o, '<br>';
$o->setMember ( "a" );
echo $o, '<br>';


Expected result:
----------------
The expected result would be for me:

Notice: undefined member ``DeriveTest::$member'' in ...\test.php on
line 12
Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?

or something of the sort

Actual result:
--------------
The actual result is:

Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?


------------------------------------------------------------------------


--
Edit this bug report at [url]http://bugs.php.net/?id=26325&edit=1[/url]

[drm at melp dot nl]

ID: 26325
User updated by: drm at melp dot nl
Reported By: drm at melp dot nl
Status: Open
Bug Type: Feature/Change Request
Operating System: Windows XP
PHP Version: 5.0.0b2 (beta2)
New Comment:

You are right, i hadn't researched the problem that well, since i
assumed php5 would treat properties the php4-style the same way as php4
itself. But you are right; the code sample above when ran in php5
doesn't give a notice, though php4 does.


Previous Comments:
------------------------------------------------------------------------

[2003-11-22 10:26:03] [email]abies@php.net[/email]

Actually, the main issue here is that PHP doesn't give a notice at all
if you access an undefined property, whether it is a private property
in a base class or not.



------------------------------------------------------------------------

[2003-11-22 09:05:03] drm at melp dot nl

Excuse me, but you are *totally* missing my point here. You are telling
me things i had already pointed out in the first post.

I'll reduce my feature request to one simple line:

Can *at least* a "notice" be triggered when a private member variable
does not exist but is accessed? And by accessed i do NOT mean
assigned!

You're saying it behaves the same way php4 does, but that's just plain
bs. See the following code in PHP4:

<?
error_reporting ( E_ALL );
class Test {
function getMember () {
return $this->member;
}
}
$t = new Test ();
echo $t->getMember ();
?>

This would yield the following notice:
Notice: Undefined property: member in test.php on line 5

All i'm asking is that some notice of the SAME sort can be implemented
in php5 when trying to access parent private members.

------------------------------------------------------------------------

[2003-11-20 11:46:55] [email]jay@php.net[/email]

There are two issues here.

First, PHP 5 is just acting like PHP 4 did -- you can
initialize a member of an object without explicitly
declaring it in the class definition and PHP won't
complain.

Second, Test::$member and DeriveTest::$member aren't the
same things. Test::$member being private, it's only
accessible and visible from within Test. DeriveTest has no
idea it exists, so it creates its own public member called
$member. If you do a print_r($o) at the end of your
script, you'll see that there are two members called
$member, one of which is private and the other public.

So yes, this is intended behaviour. One of the main ideas
of private members is that they aren't even visible from
derived classes. If you try to access a private member
from a parent class, the derived class won't see it and
will instead try using its own member, and if that doesn't
exist it will implicitly create it.

J

------------------------------------------------------------------------

[2003-11-20 04:45:48] drm at melp dot nl

Here's a more explanatory piece of code:
[url]http://gerard.yoursite.nl/php.net/private-members.phps[/url]

------------------------------------------------------------------------

[2003-11-19 17:49:24] drm at melp dot nl

Description:
------------
Hi :)

I read in the new features list of Zend Engine 2 that access modifiers
like private/protected are introduced, but something really weird comes
in mind when reading carefully.

Private members are returned _empty_ wheing tried to be accessed from
derived classes. "Intended behaviour", is said. OK, i can live with
that. But even when i turned on notices with error_reporting, nothing
is noticed?

The case grows when looking at the following code sample. This could
produce very weird bugs when writing PHP code (i hope you can see that
;)), so I would like to convince you all to at least implement a Notice
when trying to access (non-defined) private (parent) members?

It would do the coders not using E_ALL no harm :) Please consider this
:)

Reproduce code:
---------------
error_reporting ( E_ALL );
class Test {
private $member;
function __construct () { $this->member = "Test constructor";
}
function __toString () { return "Member contains:
{$this->member}"; }
function getMember () { return $this->member; }
function setMember ( $m ) { $this->member = $m; }
}
class DeriveTest extends Test {
function __construct () { parent::__construct (); }
function __toString () { return "Member contains:
{$this->member}, though getMember() says: " . $this->getMember() ."?";
}
function setMember ( $m ) { $this->member = $m; }
}
$o = new DeriveTest ();
echo $o, '<br>';
$o->setMember ( "a" );
echo $o, '<br>';


Expected result:
----------------
The expected result would be for me:

Notice: undefined member ``DeriveTest::$member'' in ...\test.php on
line 12
Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?

or something of the sort

Actual result:
--------------
The actual result is:

Member contains: , though getMember() says: Test constructor?
Member contains: a, though getMember() says: Test constructor?


------------------------------------------------------------------------


--
Edit this bug report at [url]http://bugs.php.net/?id=26325&edit=1[/url]

[jay@php.net]

ID: 26325
Updated by: [email]jay@php.net[/email]
Reported By: drm at melp dot nl
Status: Open
-Bug Type: Feature/Change Request
+Bug Type: Zend Engine 2 problem
Operating System: Windows XP
PHP Version: 5.0.0b2 (beta2)
New Comment:

Take your original example and edit it so it works in PHP
4. It runs in both 4 and 5 without a notice. Based on your
original example code, that isn't "just plain bs."

Upon further inspection based on your second example,
there is definitely something weird going on here. This is
most likely related to #26182.

J

I'm not positive, but I think this may have something to
do with #26182.

J


Previous Comments:
------------------------------------------------------------------------

[2003-11-22 18:57:46] drm at melp dot nl

You are right, i hadn't researched the problem that well, since i
assumed php5 would treat properties the php4-style the same way as php4
itself. But you are right; the code sample above when ran in php5
doesn't give a notice, though php4 does.

------------------------------------------------------------------------

[2003-11-22 10:26:03] [email]abies@php.net[/email]

Actually, the main issue here is that PHP doesn't give a notice at all
if you access an undefined property, whether it is a private property
in a base class or not.



------------------------------------------------------------------------

[2003-11-22 09:05:03] drm at melp dot nl

Excuse me, but you are *totally* missing my point here. You are telling
me things i had already pointed out in the first post.

I'll reduce my feature request to one simple line:

Can *at least* a "notice" be triggered when a private member variable
does not exist but is accessed? And by accessed i do NOT mean
assigned!

You're saying it behaves the same way php4 does, but that's just plain
bs. See the following code in PHP4:

<?
error_reporting ( E_ALL );
class Test {
function getMember () {
return $this->member;
}
}
$t = new Test ();
echo $t->getMember ();
?>

This would yield the following notice:
Notice: Undefined property: member in test.php on line 5

All i'm asking is that some notice of the SAME sort can be implemented
in php5 when trying to access parent private members.

------------------------------------------------------------------------

[2003-11-20 11:46:55] [email]jay@php.net[/email]

There are two issues here.

First, PHP 5 is just acting like PHP 4 did -- you can
initialize a member of an object without explicitly
declaring it in the class definition and PHP won't
complain.

Second, Test::$member and DeriveTest::$member aren't the
same things. Test::$member being private, it's only
accessible and visible from within Test. DeriveTest has no
idea it exists, so it creates its own public member called
$member. If you do a print_r($o) at the end of your
script, you'll see that there are two members called
$member, one of which is private and the other public.

So yes, this is intended behaviour. One of the main ideas
of private members is that they aren't even visible from
derived classes. If you try to access a private member
from a parent class, the derived class won't see it and
will instead try using its own member, and if that doesn't
exist it will implicitly create it.

J

------------------------------------------------------------------------

[2003-11-20 04:45:48] drm at melp dot nl

Here's a more explanatory piece of code:
[url]http://gerard.yoursite.nl/php.net/private-members.phps[/url]

------------------------------------------------------------------------

The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
[url]http://bugs.php.net/26325[/url]

--
Edit this bug report at [url]http://bugs.php.net/?id=26325&edit=1[/url]