通过引用传递密钥和值的替代方法：

Question

Can someone explain to me why you can't pass a key as reference?

Ex:

if(is_array($where)){
    foreach($where as &$key => &$value){
        $key = sec($key);
        $value = sec($value);
    }
    unset($key, $value);
}

Throws:

Fatal error: Key element cannot be a reference in linkstest.php on line 2   

Can I do something similar using array_map? All I want to do is iterate over an associative array, and escape both the key and value with my sec() function.

Array map is difficult for me to understand:

I have tried many things with array_map, but I can't get it to act on the keys directly.

Would I get any performance benefit using array map than just using a foreach loop?

What I don't like about foreach is that I can't act on the array directly, and have to deal with creating temporary arrays and unsetting them:

foreach($where as $key => $value){
 $where[secure($key)] = secure($value);
}

This might fail if it finds something to escape in the key, adding a new element, and keeping the unescaped one.

So am I stuck with something like this?

$temparr = array();
foreach($where as $key => $value){
 $temparr[secure($key)] = secure($value);
}
$where = $temparr;
unset($temparr);

Any alternatives?

Answer 1

Can someone explain to me why you can't pass a key as reference?

Because the language does not support this. You'd be hard-pressed to find this ability in most languages, hence the term key.

So am I stuck with something like this?

Yes. The best way is to create a new array with the appropriate keys.

Any alternatives?

The only way to provide better alternatives is to know your specific situation. If your keys map to table column names, then the best approach is to leave the keys as is and escape them at their time of use in your SQL.