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Date: Sat, 14 Feb 2015 21:37:41 +0000
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To: Robert Stoll <php@tutteli.ch>
Subject: Re: [PHP-DEV] [RFC] Void Return Type
From: ajf@ajf.me (Andrea Faulds)

Hi Robert,

> On 14 Feb 2015, at 21:23, Robert Stoll <php@tutteli.ch> wrote:
>=20
> I think a void type for PHP would make sense but only if the return =
value of such a function cannot be used.

Why? If the return value cannot be used, it prevents the function being =
used with any API that stores the return value of a callback. That=E2=80=99=
s not terribly nice.

A void return value doesn=E2=80=99t need to enforce anything on the =
caller. PHP has always filled in missing values with NULLs, including =
return values, like other dynamic languages do here.

> Otherwise it is another reason for people to laugh at PHP and =
justifiably so, telling that a function does not return anything but =
return null is very inconsistent.

It does implicitly return NULL, but NULL is a useless value, and it=E2=80=99=
s returned implicitly, rather than explicitly. I don=E2=80=99t think =
it=E2=80=99s really that ludicrous.

> I suggest to use one of the following behaviours:
> 1. declaring a function void does not return anything (hence is like =
echo to a certain agree)

That makes it cease to be a function in the PHP sense. PHP always allows =
functions to be used in expressions.

> 2. declaring a function void does return a thing of type void (that =
would be similar to Unit in scala)

We don=E2=80=99t need another form of NULL.

Also, a thing of type void could be passed around, just as the unit type =
can be in other languages, so it wouldn=E2=80=99t do what you want it =
to.

> 3. instead of void a function can be declared to be of type null -> =
almost the same behaviour as your RFC but without the inconsistency

That seems like a strange solution. You=E2=80=99re requiring the =
function to always return a useless value.

--
Andrea Faulds
http://ajf.me/