Req #63713 [Com]: Need an "UNDEFINED" type
Edit report at https://bugs.php.net/bug.php?id=63713&edit=1
ID: 63713
Comment by: metamarkers at gmail dot com
Reported by: liquid_nitrogen_4ever at yahoo dot com
Summary: Need an "UNDEFINED" type
Status: Wont fix
Type: Feature/Change Request
Package: Variables related
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
True, but checking for nested indices in arrays is a huge pain and often results in code
duplication.
$x = [];
Implicit array expansion is great:
$x['a']['b']['c'] = 1; // works
Example where this would be useful is the ternary operator:
return isset($x['very']['dimensional']['element']) ?
$x['very']['dimensional']['element'] : $default;
Why not:
return $x['very']['dimensional']['element'] ? : $default;
I could see this working for objects, too. Basically any undefined symbol would resolve to
UNDEFINED.
IMO since PHP doesn't throw native exceptions for nonexistent indices, UNDEFINED should be
supported. Otherwise PHP
should throw an out of bounds exception instead of crashing, and the following code should work:
try {
echo $x['x']['y']['z']; // doesn't exist
}
catch (Exception $e) {
echo $e->getMessage();
}
Previous Comments:
------------------------------------------------------------------------
[2012-12-07 01:51:00] aharvey@php.net
I don't see much value in this: it's an unusual use case, would require engine changes,
and you can already check if a variable is defined with
array_key_exists('notExistentVariable', get_defined_vars()).
------------------------------------------------------------------------
[2012-12-06 17:42:43] liquid_nitrogen_4ever at yahoo dot com
Description:
------------
Consider the following scenario currently in PHP:
var_dump($notExistentVariable);
-> NOTICE: Undefined variable notHere on line 1
NULL
isset($notExistentVariable);
-> FALSE
$foo = null;
var_dump($foo);
-> NULL
isset($foo);
-> FALSE
If there were an UNDEFINED "type" (in the same sense that there is a NULL), the
above scenarios would change to:
var_dump($notExistentVariable);
-> UNDEFINED
isset($notExistentVariable);
-> FALSE
$foo = null;
var_dump($foo);
-> NULL
isset($foo);
-> TRUE
However, unlike NULL, you would NOT be allowed to explicitly initialize
something to UNDEFINED.
$x=UNDEFINED;//error: if you want it to be undefined, don't declare it.
However, having just:
$x;
makes sense (to me at least) as shortcut to:
$x=NULL;
In other words, if a variable is declared but not explicitly initialized, it
will implicitly be set to NULL (which is
essentially what you are already doing, but one can't really differentiate
between declared and undeclared variables).
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=63713&edit=1
Thread (3 messages)