On Sat, Jul 5, 2014 at 9:22 AM, Kris Craig <kris.cr...@gmail.com> wrote:
> On Fri, Jul 4, 2014 at 2:38 PM, Xen <x...@dds.nl> wrote: > > > On Fri, 4 Jul 2014, Levi Morrison wrote: > > > > For completeness, it is available in Perl and I believe Perl had it > >> first; not completely sure though. > >> > > > > Okay, I never used Perl. > > > > > > I don't think changing isset would be beneficial, sadly. I wish it > >> only checked that a variable exists and didn't do the not null check > >> but it's used very, very widely. > >> > > > > As long as people don't have to use isset anymore to check for a > not-null, > > perhaps over time this widespreadedness would become less. > > > > As soon as you can use "unless (is_null())" to check whether a variable > > exists and is not null, the need for using isset for this should greatly > > diminish... > > > > Just my perspective. I don't know what other people think, the boogieman > > of this list seems to not want to discuss anything related to this, so I > > don't know. > > > > I mean for me it means having to rethink my thinking, i.e. to get used to > > this new statement. But it would probably become very natural? > > > > I would imagine a lot of people becoming enthusiastic about an "unless" > > statement. It is also a sexy thing to introduce and it doesn't require > any > > changes to existing code. > > > > Again, just my perspective. Curious what other people really think at > this > > point. > > > > Regards, Bart > > > > > > -- > > PHP Internals - PHP Runtime Development Mailing List > > To unsubscribe, visit: http://www.php.net/unsub.php > > > > > I'm not much into Perl or Ruby, either, but I agree that an unless keyword > would be a very nice thing to have. However, I'm still not sure how that > would solve the isset problem. If the variable doesn't exist, are you > saying that encapsulating it within the unless arg would prevent an > undefined variable notice from being thrown? If so, could someone > elaborate on why that is? And if not, then while I do agree it's a good > idea on its own merits, I don't think it solves the issue we're mulling > over here. > > Currently, this is what's available for checking a variable's status > without throwing any errors: > > Variable exists and !== NULL: isset( $var ) > Variable === NULL or doesn't exist: !isset( $var ) > Variable == NULL or doesn't exist: empty( $var ) > Variable exists and != NULL: !empty( $var ) > Variable exists (including NULL): ???? > Yep, nothing exists for that; we have a whole bunch of `_exists()` functions, but not e.g. `variable_exists()` or even a dedicated `exists` opcode. > Variable exists and === NULL: ???? > That's simply `@$var === null` or `@is_null($var)` of course ;-) > > It's those last two cases that we currently don't have any streamlined > approach for. If a variable is NULL and you use isset() on it, the return > will be FALSE. So if you were to do something like isset( $var ) && $var > === NULL, that statement will always return FALSE, even you set the > variable with $var = NULL beforehand. You'll get the same problem using > empty(). In other words, as far as I can tell, there's currently no way to > tell if a variable is set and NULL (or just set with any value including > NULL) in PHP. > > The closest thing I could find that accomplishes this is property_exists(). > That function will return TRUE even on NULL values. But as I understand > it, that function only works on properties; i.e. variables that are a part > of a class. There doesn't seem to be any option for doing this with > procedural variables. We know that setting a variable to NULL in PHP is > not the same as unsetting it because referring to it later won't throw an > undefined notice, but aside from catching that notice itself, there doesn't > seem to be any way to accomplish this. Am I missing something? I realize > it's an edge case, but it still needs to be covered. > > --Kris > -- -- Tjerk
