[PHP-DEV] Detecting if a null variable exists?
Is it just me or are we missing a way in the language to check if a
variable that has been set to NULL exists or not?
is_null() on an unset variable throws a NOTICE.
$var === null throws a notice.
So, you have to use isset()? But, ah,
$var = null;
if(isset($var))
yields false.
Is array_key_exists("var", $GLOBALS) the only solution to this problem?
Seems silly.
perhaps an var_exists() function is needed to fill this hole?
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Brian.
http://brian.moonspot.net/
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Re: [PHP-DEV] Detecting if a null variable exists?
On Fri, Jun 11, 2010 at 19:43, Brian Moon wrote:
> Is it just me or are we missing a way in the language to check if a variable
> that has been set to NULL exists or not?
>
> is_null() on an unset variable throws a NOTICE.
> $var === null throws a notice.
>
> So, you have to use isset()? But, ah,
>
> $var = null;
> if(isset($var))
>
> yields false.
>
> Is array_key_exists("var", $GLOBALS) the only solution to this problem?
This question creeps up every once in a while, and I have seen
bunchload of code that uses array_key_exists("foo", $array); rather
then isset($array["foo"]) because of it.
I however have never seen a proper usecase..
I tend to "initialize" my variables, and array keys, as null, so I
never have to do these kind of checks. And if you don't initialize
your variables, then you can turn of E_NOTICE if it bothers you.
-Hannes
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Re: [PHP-DEV] Detecting if a null variable exists?
Hello !
Is it just me or are we missing a way in the language to check if a
variable
that has been set to NULL exists or not?
is_null() on an unset variable throws a NOTICE.
$var === null throws a notice.
So, you have to use isset()? But, ah,
$var = null;
if(isset($var))
yields false.
Is array_key_exists("var", $GLOBALS) the only solution to this problem?
This question creeps up every once in a while, and I have seen
bunchload of code that uses array_key_exists("foo", $array); rather
then isset($array["foo"]) because of it.
I however have never seen a proper usecase..
class foo {
public function __call($method, $arguments)
{
// We MUST have at least ONE argument !
if (array_key_exists(0, $arguments) === false) //
isset($arguments[0]) return false if first argument has null value
{
trigger_error('First argument of method ' . $method . '()
must be defined', E_USER_ERROR);
}
...
}
}
$foo = new foo();
$foo->magicCallToMethod(null); // no error
$foo->magicCallToMethod(); // error
Best regards,
Fred
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Frédéric Hardy : Architecte d'application/Admin. système/Ergonome
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Re: [PHP-DEV] Detecting if a null variable exists?
Frederic Hardy wrote:
>> I however have never seen a proper usecase..
>
> class foo {
> public function __call($method, $arguments)
> {
> // We MUST have at least ONE argument !
> if (array_key_exists(0, $arguments) === false) //
> isset($arguments[0]) return false if first argument has null value
Why not simply
if (count($arguments) == 0)
..
which is simpler and clearer?
I agree with Hannes that most "usecases" should be solved differently
anyway.
- Chris
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