Regarding the earlier behavior I noticed regarding references: now I've
come across something REALLY weird. Check this out:
?php
// Dummy class
class Test
{
var $myString;
}
// Instantiate it
$object = new Test();
// Create a member
$object-myString = 'hello';
// Test function
function testObject()
{
global $object;
// Make a copy of the member variable (no '')
$newString = $object-myString;
// Return the COPY
return $newString;
}
// Grab the return from the function (notice the '')
$copiedString = testObject();
// Modify it
$copiedString = 'goodbye';
// Print the original and the copy out
echo === array ===\n;
echo $object-myString . \n;
?
Here's the output:
=== array ===
goodbye
Huh?! I even made a copy inside the function! Note that just as before
(see original message), the following change fixes things:
function testObject()
{
global $object;
// Create a reference to the member variable
$newString = $object-myString;
// Return the reference
return $newString;
}
Now the output is as expected(?):
=== array ===
hello
Can anyone tell me what's going on here? I don't think this is at all
the correct behavior.
On Sun, 2002-10-20 at 05:02, Matthew Bogosian wrote:
Howdy all,
I have stumbled onto a reference behavior I cannot explain. Here's my
problem: I'm trying to return a copy of a member variable. The function
is not declared to return a reference, but it seems as if the user can
override this. Here's a non-object example:
?php
// Create an array
$array = array('foo', 'bar', 'baz');
// This function merely returns a copy of the array
function testArray()
{
global $array;
return $array;
}
// Grab the return from the function (notice the '')
$copiedArray = testArray();
// Modify it
$copiedArray[] = 'quux';
// Print the original and the copy out
echo === array ===\n;
var_dump($array);
echo === copiedArray ===\n;
var_dump($copiedArray);
?
Running this yields exactly what you would expect:
=== array ===
array(3) {
[0]=
string(3) foo
[1]=
string(3) bar
[2]=
string(3) baz
}
=== copiedArray ===
array(4) {
[0]=
string(3) foo
[1]=
string(3) bar
[2]=
string(3) baz
[3]=
string(4) quux
}
So far, so good. This is as expected (even if the caller tries to use
the '', he's getting the reference to the copy). Now instead of a
global array, let's try the exact same thing with a member of a global
object:
?php
// Dummy class
class Test
{
var $array;
}
// Instantiate it
$object = new Test();
// Create a member that is an array
$object-array = array('baz', 'bar', 'foo');
// Same function as before, only it's returning a member variable
function testObject()
{
global $object;
return $object-array;
}
// Grab the return from the function (notice the '')
$copiedArray = testObject();
// Modify it
$copiedArray['lyx'] = 'quux';
// Print the original and the copy out
echo === array ===\n;
var_dump($object-array);
echo === copiedArray ===\n;
var_dump($copiedArray);
?
Here, I would expect that the results would be exactly the same
(remember, there are absolutely no references in the declaration of
testObject() or in the body; everything *should* be a copy). Here's what
gets printed when this is run:
=== array ===
array(4) {
[0]=
string(3) baz
[1]=
string(3) bar
[2]=
string(3) foo
[lyx]=
string(4) quux
}
=== copiedArray ===
array(4) {
[0]=
string(3) baz
[1]=
string(3) bar
[2]=
string(3) foo
[lyx]=
string(4) quux
}
Whoa! $copiedArray is now a reference for the member variable! But look
what happens if I redefine the function slightly:
function testObject()
{
global $object;
$array = $object-array;
return $array;
}
Now I get what I expect again ($copiedArray doesn't point to the member
variable after calling testObject()). So what gives? Why is return
$object-member; exempt from the return declaration of the function?
This is an interesting feature. Not very intuitive...I'd call it a
bug. Has anyone else noticed this? The above behavior happens with
scalars (e.g., strings, numbers) too, not just arrays.
By the way, I'm using PHP 4.2.3.
--Matt
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