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Date: Fri, 4 Jul 2014 14:34:17 +0200
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Subject: RE: [PHP-DEV] not_null function
From: php@tutteli.ch ("Robert Stoll")

Hey,

> -----Original Message-----
> From: Xen [mailto:xen@dds.nl]
> Sent: Thursday, July 03, 2014 11:40 AM
> To: internals@lists.php.net
> Subject: [PHP-DEV] not_null function
>=20
> Heya,
>=20
> I was just wondering about something.
>=20
> It seems way more natural and flowing to have and use a "not_null"
> function in addition to some "is_null" that currently exists.
>=20
> The reason is that most of the time you are not checking null =
condition,
> you are really checking the non-null condition.
>=20
> But a line like "if (!is_null($a))" feels like there are two verbs in =
it.
>=20
> It is like you are saying "if $a is not is null".
>=20
> It is different for the "empty" function because there is no "is_" =
prefix
> in it. So "if (!empty($a)) feels completely sane.
>=20
> So generally I will *want* to test a null condition but I just hope my
> variable won't contain anything that evaluates to false and just test =
"if
> ($a)".
>=20
> If there was a not_null() I would use that instead, because "if
> (not_null($a))" only contains one "verb" instead of two.
>=20
> And I would define that helper function myself, but I don't want to =
write
> code that another person would not be able to run just because =
not_null is
> not defined in his library.
>=20
> --------
> In general I believe this is rather a problematic feature of most
> languages.
>=20
> The "if" statement implies a verb, but many functions and methods also
> contain a verb in their name.
>=20
> This seems to be only the case for the "is" verb. I know in my =
language
> (Dutch) the "to be" verb (zijn) is treated differently from all other
> verbs when it comes to the adverb/adjective difference.
>=20
> When you state "I am good" the adjective is used, but "I work good" =
should
> be "I work well". The adjective applies to the subject "I" but the =
adverb
> applies to the verb "work". I guess there are all sorts of mixtures, =
"I am
> well" is also used. But I think it is improper.
>=20
> Thus, "if (has_members())" feels natural because it uses a different =
verb
> replacing the default "is".
>=20
> But "if (is_null())" feels odd because "if (null())" would say the =
same
> thing only more concise and more natural as far as if statements go, =
or at
> least it seems that way to me.
>=20
> Personally I try to avoid those "is_something" functions whenever I =
can.
> It is not so much an issue if it is some rarely used library call.
>=20
> Like WordPress has functions like "is_single()" which returns a =
boolean
> indicating whether the currently loaded page is a single post display.
>=20
> But notice that "if (single())" would give very little information as =
to
> what you were actually testing. There is no parameter, and just =
"single"
> would be so general that it would completely obfuscate the fact that =
it
> had to do with WordPress. It would have to become "page_is_single()"
> although "page" is (improperly) dedicated to a special type of post =
that
> sits outside of the regular post structure. They ought to rename it to
> "staticpage" or "static". "page_is_single" and "page_is_home" and
> "page_is_category" would be more descriptive.
>=20
> But in any case, this language incongruency is most annoying with core
> functions you have to use all the time, or would be using all the time =
if
> they were okay.
>=20
> So my suggestion would be to consider introducing at least "not_null".
> "isset" seems to be a different category, if only because the verb is =
not
> visually separated from the condition.
>=20
> So "if (isnull($a))" would again be more natural. But because the verb =
is
> visually separated using the underscore, you get two verbs in your =
mind.
> Perhaps creating an "isnull" alias and then deprecating the "is_null"
> function would be best.
>=20
> Regards,
>=20
> Bart Schouten
>=20
> ps. please "reply all" for I am not subscribed as of yet.
>=20
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[Robert Stoll]=20

I really like how ruby tackles this problem with the syntactic sugar =
"unless" which basically is a substitute for "if( !() )".
Maybe we could consider to introduce it in PHP next? It is very natural =
to read "unless(is_null($x))" an much nicer than "if(!is_null($x)" IMO. =
And it would not only solve your issue with is_null but is_Xy =
functions/methods in general.

Cheers,
Robert=20