Re: Implicit isset/isempty check on short-ternary operator

I agree empty() is basically useless. We already have the existing ternary operator (and its shortcut) to do a boolean test, which is basically the same as empty(). The way I see it, if rather than making an isset() operator that suppresses errors and offers a default, we added both a !==null operator for the default, and a separate error-suppression mechanism, people could use the suppression mechanism with the existing boolean ternary operator if they want to (I would find that useful, as I often write things such as isset($a[$k])&&$a[$k]?"yes":"no" for that kind of thing), and use the !==null operator without error suppression (I would find that useful, too, to avoid typos). In summary, with two separate, simpler mechanisms, we could tackle these paradigms (I have used @[...] for undefined index error-suppression and $: for !==null default): 1. $v!==null ? $v : "default" $v $: "default" with notice 2. $a[$k]!==null ? $a[$k] : "default" $a[$k] $: "default" with notice 3. isset($a[$k]) ? $a[$k] : "default" $a@[$k] $: "default" without notice 4. isset($a[$k]) ? $a[$k] : null $a@[$k] without notice 5. isset($a[$k])&&!!$a[$k] !!$a@[$k] without notice 6. isset($a[$k])&&$a[$k] ? "yes" : "no" $a@[$k] ? "yes" : "no" without notice With !==null assignment (I've used $:=) we could also have: 7. if (!isset($a[$k])) $a[$k] = "default"; $a[$k] $:= "default"; without notice (the LHS of an assignment never generates one) To avoid encouraging poor coding, we would deliberately not have: 8. isset($v) ? $v : "default" $@v $: "default" without notice But it is a cinch to add it if enough people want it, and doing so wouldn't affect anyone who didn't want to use it--no backward compatibility problems on the horizon. I think that's the clincher. If we just add an isset() operator (that suppresses errors, and gives a default), we only get paradigms 3, 4, 5 and maybe 7, but worse, if we want to add any of the others later, we need to design more complicated new operators, or break backward compatibility, not just extend what we have. I personally use 1, 3, 5 and 6 quite often, and 2 and 7 occasionally, so I see great value in being able to do them all, not just the restricted set. What numbers are others interested in being able to solve? What do others think about the future-proofing issue? Ben. On 15/04/11 1:01 AM, Hannes Landeholm wrote:

I can agree that implementing ?? with isset() and not array_key_exists() would be acceptable... but empty() is a blunt compromise and much less used... The general problem is the notice being thrown when array indexes doesn't exist - which results in code duplication when you deal with it nicely. empty() tries to be a generic solution but there will always be people that has some other special definition of "emptiness" like "array that contains a single null value" and they need to write the code that defines that particular comparison anyway. You can't have a solution that makes everything easier for everyone so let's solve one thing at a time and start with the most generic problem specifically and not all minor problems that happens to partially intersect that one. ~Hannes On 14 April 2011 16:26, Ben Schmidt <mail_ben_schmidt@yahoo.com.au <mailto:mail_ben_schmidt@yahoo.com.au>> wrote:

    On 15/04/11 12:05 AM, Hannes Landeholm wrote:

        Trying to summarize this discussion... I think we can all agree that the
        main problem is "code duplication for array access when parameters are
        possibly not existing".

    For me the problem is 'code duplication when a value might be null'
    (whether an array, variable or something else, and regardless of whether
    it was set to null, or not defined at all).

        I think we all can also agree that @ can be both used properly and
        misused - and it is a blunt tool and not a nice solution to the
        previously stated problem.

    Yes.

        Some suggested that the ternary if comparison should suppress the notice
        automatically. This would break existing code and also be confusing since
        people expect a ternary if and normal if to work the same way.

    Yes.

        Some suggested ?? as an array access operator that suppresses the notice and
        has 3 variants: A: nothing specified - uses null as default, B: has default
        specified, C: returns X if index exists or Y if index doesn't exist. This
        effectively solves the code duplication problem and is a shortcut for saying
        "the array index may or may not exist".

    This only works if the test is made an isset() kind of test. If it
    remains a boolean cast, it doesn't help much. (Or at least it doesn't
    help me much.)

    I also think it's a bit too blunt. In all but the simplest expressions
    in the condition, desired notices could be silenced. I like the idea of
    being able to specify exactly which array lookups should be silenced.

    It also doesn't help the people who want an isset() style test, but
    without the notice suppression, and I think there are a few people in
    that category.

        One person said that the relation between ? and ?? and == and === would make
        the operator non-intuitive. Other people disagreed and claimed the opposite.

        So basically the discussion now is what exact characters that should be used
        to represent this operator? I really hope we can get this implemented
        quickly... I worked with $_POST yesterday and I could really use that ??
        operator.

    I still don't think we've reached agreement on exactly what we need.
    Your summary seems to me to be of some of the earliest and least
    developed ideas. I think the discussion has moved in a number of
    interesting directions since then and we should draw on that later work.

    Ben.