[PHP-BUG] Bug #55278 [NEW]: @ Error control operator prevents creation of variable
From: Operating system: Windows 7 PHP version: 5.3.6 Package: Scripting Engine problem Bug Type: Bug Bug description:@ Error control operator prevents creation of variable Description: When a function is defined with a parameter that is passed by reference, calling the function with a variable that has not been previously set will create that variable (and trigger a warning). After the function is called that variable exists (won't trigger warnings) and holds null or whatever value the function assigned to it. If you try to suppress the warning for the variable that doesn't exist at call time, it will not be created, and trying to access it after the function triggers warnings. It works as expected if you suppress errors on the function call but this is not desirable because it will also hide other errors. Test script: --- https://bugs.php.net/bug.php?id=55278&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=55278&r=trysnapshot54 Try a snapshot (PHP 5.3): https://bugs.php.net/fix.php?id=55278&r=trysnapshot53 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=55278&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=55278&r=fixed Fixed in SVN and need be documented: https://bugs.php.net/fix.php?id=55278&r=needdocs Fixed in release: https://bugs.php.net/fix.php?id=55278&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=55278&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=55278&r=needscript Try newer version: https://bugs.php.net/fix.php?id=55278&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=55278&r=support Expected behavior: https://bugs.php.net/fix.php?id=55278&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=55278&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=55278&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=55278&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=55278&r=php4 Daylight Savings:https://bugs.php.net/fix.php?id=55278&r=dst IIS Stability: https://bugs.php.net/fix.php?id=55278&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=55278&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=55278&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=55278&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=55278&r=mysqlcfg
Bug #55278 [Com]: @ Error control operator prevents creation of variable
Edit report at https://bugs.php.net/bug.php?id=55278&edit=1 ID: 55278 Comment by: lucas at threeamdesign dot com Reported by:lucas at threeamdesign dot com Summary:@ Error control operator prevents creation of variable Status: Duplicate Type: Bug Package:Scripting Engine problem Operating System: Windows 7 PHP Version:5.3.6 Block user comment: N Private report: N New Comment: Thanks, glad it wasn't just me. I did search for it but I'm not surprised I didn't find it - you can't search for "@" so I looked for "error control" and "error suppression" Previous Comments: [2011-07-26 05:05:11] larue...@php.net this is a duplicate, see #47623 ---------------- [2011-07-25 03:22:23] lucas at threeamdesign dot com Description: When a function is defined with a parameter that is passed by reference, calling the function with a variable that has not been previously set will create that variable (and trigger a warning). After the function is called that variable exists (won't trigger warnings) and holds null or whatever value the function assigned to it. If you try to suppress the warning for the variable that doesn't exist at call time, it will not be created, and trying to access it after the function triggers warnings. It works as expected if you suppress errors on the function call but this is not desirable because it will also hide other errors. Test script: --- https://bugs.php.net/bug.php?id=55278&edit=1
Bug #55278 [Dup]: @ (Error control/suppression) operator prevents creation of variable
Edit report at https://bugs.php.net/bug.php?id=55278&edit=1 ID: 55278 User updated by:lucas at threeamdesign dot com Reported by:lucas at threeamdesign dot com -Summary:@ Error control operator prevents creation of variable +Summary:@ (Error control/suppression) operator prevents creation of variable Status: Duplicate Type: Bug Package:Scripting Engine problem Operating System: Windows 7 PHP Version:5.3.6 Block user comment: N Private report: N New Comment: Made this bug easier to search for. Previous Comments: [2011-07-28 02:32:55] lucas at threeamdesign dot com Thanks, glad it wasn't just me. I did search for it but I'm not surprised I didn't find it - you can't search for "@" so I looked for "error control" and "error suppression" [2011-07-26 05:05:11] larue...@php.net this is a duplicate, see #47623 ---------------- [2011-07-25 03:22:23] lucas at threeamdesign dot com Description: When a function is defined with a parameter that is passed by reference, calling the function with a variable that has not been previously set will create that variable (and trigger a warning). After the function is called that variable exists (won't trigger warnings) and holds null or whatever value the function assigned to it. If you try to suppress the warning for the variable that doesn't exist at call time, it will not be created, and trying to access it after the function triggers warnings. It works as expected if you suppress errors on the function call but this is not desirable because it will also hide other errors. Test script: --- https://bugs.php.net/bug.php?id=55278&edit=1
Bug #52937 [Com]: call_user_func warning is inappropriate
Edit report at https://bugs.php.net/bug.php?id=52937&edit=1
ID: 52937
Comment by: lucas at threeamdesign dot com
Reported by:mryaggi at hotmail dot com
Summary:call_user_func warning is inappropriate
Status: Open
Type: Bug
Package:Scripting Engine problem
Operating System: Seven
PHP Version:5.3.3
Block user comment: N
Private report: N
New Comment:
to work around this problem put the reference in the argument array. e.g.:
function foo(&$bar) {
$bar = 5;
}
$a = 1;
$b = 2;
call_user_func('foo', $a);
call_user_func_array('foo', array(&$b));
var_dump($a, $b);
gives
int(1)
int(5)
Previous Comments:
[2010-10-11 11:00:54] mryaggi at hotmail dot com
Ok, I'm going to keep it simple.
You say "[I] have to use call_user_func_array instead".
Please show me how.
Note : I'm just trying to avoid the warning properly.
This would be quite a solution :
call_user_func('ExprectRef', & $p);
call_user_func_array('ExprectRef',array( & $p));
But it's a pity you have to write & TWICE. One in the signature, one in the
call_user_func call.
...it looks so much like the depreciated call-time pass-by-reference.
Don't you think?
[2010-10-03 00:02:58] cataphr...@php.net
You *should* know whether the function takes references; it's part of its
signature.
If it does take references you cannot use call_user_func, and have to use
call_user_func_array instead.
[2010-09-29 19:31:10] mryaggi at hotmail dot com
Thank you for your quick reply.
You say : "Use call_user_func_array()."
But you can run the test script with call_user_func_array() instad, and still
you will get those warnings.
My point is : when you call call_user_func you have no idea whether the
function called expects references or not (values).
The only solution I see is to always give references to call_user_func*()
For ex:
-
function MY_call_user_func_array($Func,$Args)
{
foreach(array_keys($Args) as $i) { $Args[$i] =& $Args[$i]; }//make it a ref
call_user_func_array($Func,$Args);
}
function test(&$z){ echo "ok : " . $z . "\n";}
$a = 1;
MY_call_user_func_array('test',array($a));
-
And here we are! IT WORKS!
but it I feel like I just learnt how to poo in PHP...
[2010-09-28 03:13:28] cataphr...@php.net
Yes, this may be confusing. The problem is that the level of indirection added
means when the function test() is actually called by the implementation of
call_user_func() via zend_call_function, information about the arguments is
lost. Use call_user_func_array().
Tests 1 and 3 are basically the same. The manual for call_user_func has a note:
«Note that the parameters for call_user_func() are not passed by reference.»
Since call_user_func doesn't receive its parameters by reference, by the time
they reach it, it has no way of knowing if the parameters were sent by
reference or not.
Test 2 is a different matter. But you are actually passing a reference to
test() because zend_call_function() is nice and when you pass a non-reference
to a function that expects a reference and the non-reference has refcount 1, it
converts it into a reference. See
http://lxr.php.net/opengrok/xref/PHP_TRUNK/Zend/zend_execute_API.c#860
Again, this makes sense if you're writing an extension and using
zend_call_function() and passing it a variable you've created. I don't see how
this can be fixed, except by adding something like fci->no_separation that
doesn't create a reference even if the refcount is 1. Not sure if it's worth
the trouble.
[2010-09-27 19:31:16] mryaggi at hotmail dot com
Description:
call_user_func now issue a warning in PHP5.3 when giving a value instead of a
reference.
However, this warning shows up in inappropriate cases.
Test script:
---
Expected result:
ok : 1
Warning: Parameter 1 to test() expected to be a reference, value given
in
...
ok : 3
Actual result:
--
Warning: Parameter 1 to test() expected to be a reference, value given
in
...
ok : 2
Warning: Parameter 1 to test() expected to be a reference, value given
in
...
--
Edit this bug report at https://bugs.php.net/bug.php?id=52937&edit=1
