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allow extension writers to ignore E_NOTICE warnings about unset variables

php.internals

D. Dante Lorenso

20 years ago

All,

Is there a way to define a function in an extension which would not
require a passed in variable to exist?  In other words, can ZE be
modified to allow extensions to not trigger E_NOTICE warnings if an
unset variable is passed to a function which does not care if the var is
set?

I can specify preferences about whether variables are passed by
reference or not using macros like:

* PHP_FE(..., first_arg_force_ref)
* PHP_FE(..., third_arg_force_by_ref_rest)
* PHP_FE(..., first_through_third_args_force_ref)

Which probably boil down somewhere into:

* #define ZEND_SEND_BY_VAL     0
* #define ZEND_SEND_BY_REF     1
* #define ZEND_SEND_PREFER_REF 2

And I notice that if a variable is passed by reference to an extension
function, no E_NOTICE is thrown.  Well, can we extend this concept
further to say something like:

* #define ZEND_SEND_WHO_CARES_IF_IT_EXISTS_OR_NOT 4

*but with a better name, of course*

Then, extension developers can write 'ifsetor', 'coalesce', and 'filled'
as extensions (by themselves) and not need those specific functions
added to the 'PHP core language' per-se.

Dante

Antony Dovgal

20 years ago

On 12.05.2006 02:49, D. Dante Lorenso wrote:

> All,
>
> Is there a way to define a function in an extension which would not
> require a passed in variable to exist?  In other words, can ZE be
> modified to allow extensions to not trigger E_NOTICE warnings if an
> unset variable is passed to a function which does not care if the var is
> set?
>
> I can specify preferences about whether variables are passed by
> reference or not using macros like:
>
>     * PHP_FE(..., first_arg_force_ref)
>     * PHP_FE(..., third_arg_force_by_ref_rest)
>     * PHP_FE(..., first_through_third_args_force_ref)
>
> Which probably boil down somewhere into:
>
>     * #define ZEND_SEND_BY_VAL     0
>     * #define ZEND_SEND_BY_REF     1

This one is what you need.

--
Wbr,
Antony Dovgal

D. Dante Lorenso

20 years ago

Antony Dovgal wrote:

> On 12.05.2006 02:49, D. Dante Lorenso wrote:
>>     * #define ZEND_SEND_BY_REF     1
> This one is what you need.

I don't think it is.  The variable did not exist before the function was
called and should STILL not exist afterwards.  I believe when you pass
by reference, the variable will exist after the call.  This is bad since
future calls to 'isset' will suddenly start returning TRUE when they
shouldn't.

Dante

Antony Dovgal

20 years ago

On 12.05.2006 03:05, D. Dante Lorenso wrote:

> Antony Dovgal wrote:
>> On 12.05.2006 02:49, D. Dante Lorenso wrote:
>>>     * #define ZEND_SEND_BY_REF     1
>> This one is what you need.
> I don't think it is.  The variable did not exist before the function was
> called and should STILL not exist afterwards.  I believe when you pass
> by reference, the variable will exist after the call.

Only if you created it during the call.

<?php
function foo(&$arg) {
}

foo($nonex);
var_dump(isset($nonex));
?>

bool(false)

>  This is bad since
> future calls to 'isset' will suddenly start returning TRUE when they
> shouldn't.

--
Wbr,
Antony Dovgal

Stefan Walk

20 years ago

Antony Dovgal wrote:

> Only if you created it during the call.
>
> <?php
> function foo(&$arg) {
> }
>
> foo($nonex);
> var_dump(isset($nonex));
> ?>
>
> bool(false)
>

$ php -r 'function foo(&$foo){} function bar(){ foo($var);
var_dump(get_defined_vars());} bar();'
array(1) {
["var"]=>
NULL
}

Marcus Börger

20 years ago

Hello D.,

no, the compiler generates code that makes the executor generate the
variable and complain prior to performing the call. In a zend extension
you could try to hook into that process.

marcus

Friday, May 12, 2006, 12:49:45 AM, you wrote:

> All,

> Is there a way to define a function in an extension which would not
> require a passed in variable to exist?  In other words, can ZE be
> modified to allow extensions to not trigger E_NOTICE warnings if an
> unset variable is passed to a function which does not care if the var is
> set?

> I can specify preferences about whether variables are passed by
> reference or not using macros like:

>     * PHP_FE(..., first_arg_force_ref)
>     * PHP_FE(..., third_arg_force_by_ref_rest)
>     * PHP_FE(..., first_through_third_args_force_ref)

> Which probably boil down somewhere into:

>     * #define ZEND_SEND_BY_VAL     0
>     * #define ZEND_SEND_BY_REF     1
>     * #define ZEND_SEND_PREFER_REF 2

> And I notice that if a variable is passed by reference to an extension
> function, no E_NOTICE is thrown.  Well, can we extend this concept
> further to say something like:

>     * #define ZEND_SEND_WHO_CARES_IF_IT_EXISTS_OR_NOT 4

> *but with a better name, of course*

> Then, extension developers can write 'ifsetor', 'coalesce', and 'filled'
> as extensions (by themselves) and not need those specific functions
> added to the 'PHP core language' per-se.

> Dante

Best regards,
Marcus

D. Dante Lorenso

20 years ago

Marcus Boerger wrote:

> no, the compiler generates code that makes the executor generate the
> variable and complain prior to performing the call.
>

The executor doesn't complain about unset variables prior to calling
functions by reference, so I was thinking it could be modified to also
not complain when calling functions that don't care about set
variables.  Naturally, the unset variable would evaluate as NULL and be
passed as such, just there would be no E_NOTICE.

> In a zend extension you could try to hook into that process.
>

How do you mean?  Got any pointers?

Dante

Marcus Börger

20 years ago

Hello D.,

Friday, May 12, 2006, 1:10:41 AM, you wrote:

> Marcus Boerger wrote:
>> no, the compiler generates code that makes the executor generate the
>> variable and complain prior to performing the call.
>>

> The executor doesn't complain about unset variables prior to calling
> functions by reference, so I was thinking it could be modified to also
> not complain when calling functions that don't care about set
> variables.  Naturally, the unset variable would evaluate as NULL and be
> passed as such, just there would be no E_NOTICE.

>> In a zend extension you could try to hook into that process.
>>

> How do you mean?  Got any pointers?

Sorry no. Maybe Sara captures that in her book. Only places i could
imagine to touch what you need is Saras pecl/run-kit.

Best regards,
Marcus