Re: not_null function

On Sat, Jul 5, 2014 at 3:39 PM, Tjerk Meesters <tjerk.meesters@gmail.com> wrote: > > > > On Sat, Jul 5, 2014 at 9:22 AM, Kris Craig <kris.craig@gmail.com> wrote: > >> On Fri, Jul 4, 2014 at 2:38 PM, Xen <xen@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($var) of course ;-) > Obviously spoke to soon ... what I've written there is basically an ugly !isset($var). Sorry for the extra noise. > >> >> 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 > -- -- Tjerk