ID: 36405
User updated by: thom at genx dot net
-Summary: inline assignment of a variable used as a reference
fails
Reported By: thom at genx dot net
Status: Bogus
Bug Type: Feature/Change Request
Operating System: Linux (gentoo)
PHP Version: 5.1.2
New Comment:
According to the documentation, PHP supports function arguments that
are passed by value (default), reference, value with default, and
variable argument lists (> PHP 4). It does not say that passing by
expression is supported.
funcByValue($a++);
funcByValue($a + 9);
funcByValue($a = $b + 1);
I would like to think that PHP will continue to support the current
behavior of the above examples because it understands that expressions
can be reduced to a more base form. In the examples above, it is
assumed that PHP reduces the expressions to a value and that resulting
value is then used in the function call since it supports "passing by
value" (and not passing by expression).
With that in mind, an assignment expression can be reduced to a
variable. In the more general scenario, expressions whose outer most
component (based on the rules of precedence) is of assignment type can
be reduced to a variable. A variable is the required form for "passing
by reference".
Yes, an expression is an expression as you so nicely stated, but they
can be reduced. If expressions are reduced to a value so they can be
passed by value, why can't an assigment expression be reduced to a
variable so it can be passed by reference?
I understand that there is a workaround, but please do acknowledge the
fact that expressions work in the case of passing by value because they
are first reduced to a value (and continued support is planned). In the
case of an assignment expression and passing by reference, it would
require applying another rule of reduction and may still yield a
consistent interface within PHP.
PHP does still consider itself a scripting language and a change like
this might be a nuance meant for a programming language, but other
changes seem to imply that the PHP development team is open to such
suggestions (e.g. argument type hinting).
Thank you for considering this.
Previous Comments:
------------------------------------------------------------------------
[2006-02-16 07:26:09] [EMAIL PROTECTED]
No, it won't change.
Expressions are expressions, you can't pass them by reference.
------------------------------------------------------------------------
[2006-02-16 02:17:39] thom at genx dot net
Sorry, I left it as 'Bogus' this time. I thought that meant it was
closed and that any further responses were ignored.
This is changed to a Feature/Change request in hopes that it will
receive some attention and/or debate.
Thanks.
------------------------------------------------------------------------
[2006-02-16 01:58:35] [EMAIL PROTECTED]
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php
Read the manual, the definition of an expression and a variable are
clearly explained. And keep it this bug as bogus it is not a bug (and
the behavior is documented).
------------------------------------------------------------------------
[2006-02-16 01:43:39] thom at genx dot net
Maybe this is not a good argument, but other languages still interpret
that as passing $x by reference, but to do the assigment first. I am
going to use C++ as an example (since PHP has tried to model some of
its behavior from):
#include <iostream>
using namespace std;
void
foo(int &x)
{
x = 9;
}
int
main()
{
int x;
foo(x = 1);
cout << x << "\n";
}
The output is: 9
There are no compiler warnings or errors (at the highest reporting
level). I understand that this is not C++, but previous versions of
PHP (< 5.1.2) behaved consistently with other programming languages in
the way that inline assignments were handled.
Is it something the PHP development team would consider (reverting back
to a more consistent behavior)?
Thanks,
thom
------------------------------------------------------------------------
[2006-02-16 01:15:45] [EMAIL PROTECTED]
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php
$x = 'foo' is an expression and cannot be passed by reference. Enable
E_STRICT to see the message.
------------------------------------------------------------------------
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the rest of the comments, please view the bug report online at
http://bugs.php.net/36405
--
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