php5 method return reference error?

21 years ago by Walter A. Boring IV — view source

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Howdy,
I'm playing with php5 (from cvs), and came accross a strange error
that doesn't happen with php4. Maybe someone can shed some light on
this for me?

I get the error
"Fatal error: Only variables or references can be returned by reference
in /home/waboring/devel/html/test.php on line 11"

Here is the php code

<?php

class foo {
var $test = 0;
}

class bar {
function &get() {
//both of these fail
//return new foo;
return $this->_buildOBJ();
}

function &_buildOBJ() {
    $obj = new foo();
    $obj->test = 'worked';
    return $obj;
}

}

$bar = new bar;
$foo = $bar->get();
echo $foo->test;
?>

This doesn't happen in php4.
This seems to go away if I change the bar::get() method to

function &get() {
$obj =& $this->_buildOBJ();
return $obj;
}

This seems like a bug to me, since both cases the return value is a
reference of an object?

Thanks Walt

21 years ago by Analysis & Solutions — view source

unread

Hi Walter:

"Fatal error: Only variables or references can be returned by reference
in /home/waboring/devel/html/test.php on line 11"

This is the expected behavior.

This has been discussed in the bugs database and on this list. I even
started a thread on this topic today.

This group is archived in the following two places:
http://groups.google.com/groups?group=mailing.www.php-dev
http://marc.theaimsgroup.com/?l=php-dev

The topic is discussed in bug 24687:
http://bugs.php.net/bug.php?id=24687

Enjoy,

--Dan

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21 years ago by walt boring — view source

unread

Analysis & Solutions wrote:

Hi Walter:

"Fatal error: Only variables or references can be returned by reference
in /home/waboring/devel/html/test.php on line 11"

This is the expected behavior.

This has been discussed in the bugs database and on this list. I even
started a thread on this topic today.

This group is archived in the following two places:
http://groups.google.com/groups?group=mailing.www.php-dev
http://marc.theaimsgroup.com/?l=php-dev

The topic is discussed in bug 24687:
http://bugs.php.net/bug.php?id=24687

Enjoy,

--Dan

This is very sad that the only real argument in the bug against fixing
it was
that it was hard. Come on! This is such a fundamental thing to be able
to do.

function &foo() {
return something_else();
}

How can they say this won't be fixed? I just don't get it. This is
going to make a lot
of php folks upset, and make it much more painfull to upgrade to php5.
I work on several projects,
commercial and non-commercial, that this one bug will prevent me from
moving to php5 without
a lot of changing of classes and code, let alone the re-qualification of
the applications due to this change.
This is just sad.

Walt

21 years ago by Analysis & Solutions — view source

unread

Hi Walt:

This is very sad that the only real argument in the bug against fixing
it was
that it was hard. Come on! This is such a fundamental thing to be able
to do.

function &foo() {
return something_else();
}

The thing is, as I understand it, references are referring to a variable.
Your example doesn't have a variable to refer to.

If I misunderstand what's going on, I trust someone on the list will
correct me.

going to make a lot
of php folks upset, and make it much more painfull to upgrade to php5.

But the error rests on the people who made the mistake of coding returns
by reference on items that aren't variables.

Enjoy,

--Dan

21 years ago by walt boring — view source

unread

Analysis & Solutions wrote:

Hi Walt:

This is very sad that the only real argument in the bug against fixing
it was
that it was hard. Come on! This is such a fundamental thing to be able
to do.

function &foo() {
return something_else();
}

The thing is, as I understand it, references are referring to a variable.
Your example doesn't have a variable to refer to.

If I misunderstand what's going on, I trust someone on the list will
correct me.

going to make a lot
of php folks upset, and make it much more painfull to upgrade to php5.

But the error rests on the people who made the mistake of coding returns
by reference on items that aren't variables.

This also fails when you do

function &foo() {
return new bar();
}

the something_else() function in my first example could return a variable.

function &foo() {
return something_else();
}

function &something_else() {
$foo = 'a';
return $foo;
}

This also fails, and it shouldn't.

Walt

21 years ago by Derick Rethans — view source

unread

The thing is, as I understand it, references are referring to a variable.
Your example doesn't have a variable to refer to.

If I misunderstand what's going on, I trust someone on the list will
correct me.

Your assesment is right. BUT, it is indeed quite a huge BC break and
people already said that it is going to be addressed (AFAIK Zeev
mentioned that).

Derick

21 years ago by Analysis & Solutions — view source

unread

Howdy:

Your assesment is right. BUT, it is indeed quite a huge BC break and
people already said that it is going to be addressed (AFAIK Zeev
mentioned that).

I've heard on several occasions, some fairly recently, that it won't.

--Dan

21 years ago by walt boring — view source

unread

Derick Rethans wrote:

The thing is, as I understand it, references are referring to a variable.
Your example doesn't have a variable to refer to.

If I misunderstand what's going on, I trust someone on the list will
correct me.

Your assesment is right. BUT, it is indeed quite a huge BC break and
people already said that it is going to be addressed (AFAIK Zeev
mentioned that).

Derick

According to the bug

http://bugs.php.net/bug.php?id=24687

It won't be fixed ??

Walt

21 years ago by Michael Walter — view source

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Not sure I'm missing something, but I fail to see the problem: Doesn't
PHP 5 use object references anyway? So function pla() { return new
Foo(); } would return a reference anyway, instead of copying the object
itself over?

So just removing & should fix the problem, as long as you're dealing
with objects.

Cheers,
Michael

Walter A. Boring IV wrote:

Howdy,
I'm playing with php5 (from cvs), and came accross a strange error
that doesn't happen with php4. Maybe someone can shed some light on
this for me?

I get the error
"Fatal error: Only variables or references can be returned by reference
in /home/waboring/devel/html/test.php on line 11"

Here is the php code

<?php

class foo {
var $test = 0;
}

class bar {
function &get() {
//both of these fail
//return new foo;
return $this->_buildOBJ();
}
function &_buildOBJ() {
    $obj = new foo();
    $obj->test = 'worked';
    return $obj;
}
}

$bar = new bar;
$foo = $bar->get();
echo $foo->test;
?>

This doesn't happen in php4.
This seems to go away if I change the bar::get() method to

function &get() {
$obj =& $this->_buildOBJ();
return $obj;
}

This seems like a bug to me, since both cases the return value is a
reference of an object?

Thanks Walt

21 years ago by Derick Rethans — view source

unread

Not sure I'm missing something, but I fail to see the problem: Doesn't
PHP 5 use object references anyway? So function pla() { return new
Foo(); } would return a reference anyway, instead of copying the object
itself over?

No, it's not a reference, but an object handle which still can be passed
as reference (but it's quite unuseful to do).

So just removing & should fix the problem, as long as you're dealing
with objects.

Yup.

Derick