There are two issues here. 1. Suppression of notice. I agree, it is best done only for array keys. It's not hard to initialise a variable with $var=null at the beginning of a code block to avoid such a notice, and that is the appropriate way to do it for variables.2. Offering a shortcut for the common idiom isset($x) ? $x : $y in line with the DRY design principle. A notice would never be emitted here in any case. The problem is that this idiom is still in wide use despite the shortcut ternary operator already provided, because an isset() check is different to a boolean cast. Some thoughts: - The actual intent of 2. is probably $x!==null ? $x : $y i.e. it's not about suppressing notices at all, but about offering a default value, and the idiom quite probably only uses isset() because it predated null in the language. - If we view 2. in this way, the two problems are independent, and it seems to me it would be best to solve them independently, rather than with a single operator. So, I suggest: 1. An array lookup mechanism that suppresses the notice for undefined keys. It would work the same as regular array index lookups except that the notice for undefined keys (and only for undefined keys) would not be generated (it would not just be hidden, but would never be even generated).http://news.php.net/php.internals/51877 array_key_exists($key, $array) for arrays array_key_exists($varname, get_defined_vars()) for locally scoped variables.
Apart from being long and ugly, surely that is horribly inefficient.
No need to use @.
True. And I don't think anybody is. We all know @ is dangerous and nasty and don't use it. We're not seeking an alternative to @, we're seeking an alternative to repeating ourselves by using isset()/array_key_exists()/is_null() as well as the value being tested. But we don't want to do this in a blanket way similar to @ where a whole bunch of notices are suppressed. We want to specify precisely where missing values are allowable by indicating exactly which array index lookups may silently fail (and evaluate to null). Basically we don't want to make again the mistake that @ was.
Are they attempting to determine the existence of a variable/index entry or are they attempting to determine if the variable/element is null.
For me, existence and nullness are basically the same, and I think this is the common case. The whole point of being able to set something to null is to have a 'value' to represent 'unsetness'. This is why I think solving the conditional problem should use a !==null test. That gives the flexibility to use/pass null to represent 'unsetness' but doesn't pick up zero, false, etc. like a boolean cast does. Using array_key_exists() would remove that flexibility and be less useful. As far as silencing notices goes, the rationale is that basically we want to flag that 'null is OK, even if it's a fallback'. I.e. we don't care whether a value is null because it was set to null, or because null is a fallback because the variable was never defined. Either way, null is OK, so don't tell me about it. The conditional side lets us handle nulls nicely by providing our own defaults/fallbacks if it appears. The notice-suppression side lets us say that null is OK, even if that null itself is a fallback for 'undefined'. Quite often they will be used in combination, but they are independent.
I always declare my variables. So, I don't want to use isset() as they will be an incorrect test. I use is_null(). Specifically testing the value. If I've made a mistake and NOT declared the variable (or made a typo), I want to know. I don't want to hide it with isset()/empty().
That's exactly why I think the conditional should use a !==null test, not an isset() test. Ben. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
