Re[2]: [PHP-DEV] PHP 5.1

At 17:10 14/06/2005, Sven Fuchs wrote:

This implementation of issetor() actually works fine, except it does pollute the symbol tables with empty variables ($a and $b in this examples are created, as nulls). What are the consequences of polluting the symbol tables this way?

Well, it will increase memory usage, but unless you're dealing with a huge amount of variables, that should be pretty negligible. It might also not work properly in certain cases, because PHP isn't truly capable of differentiating between variables those empty variables and real variables that contain nulls. For example, function ifsetor(&$x) { } ifsetor($foo); print $foo; will not generate a notice on a non existing variable, but will emit it if the call to ifsetor() is removed.

Should this issetor() be considered a "bad practice", probably for medium to large scale applications?

I think that a more practical implementation may be something like: function ifsetor(&$x, $default=null) {

        if (!isset($x)) {
                $x = $default;
        }
        return $x;

} i.e., assign the variable with the default value if it doesn't yet exist. I think it usually desirable (not always, naturally) and since we want the variable to exist in this case, there's no pollution issue. I fully agree with everyone else that wondered why we're discussing this. People can implement this on their own, the way they want it, with an assignment or without it, using empty() or isset(), etc. Zeev