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Date: Thu, 25 Dec 2014 04:06:14 +0000
Cc: =?utf-8?Q?Johannes_Schl=C3=BCter?= <johannes@schlueters.de>,
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To: Levi Morrison <levim@php.net>
Subject: Re: [PHP-DEV] About SUCCESS/FAILURE
From: ajf@ajf.me (Andrea Faulds)


> On 24 Dec 2014, at 23:53, Levi Morrison <levim@php.net> wrote:
>=20
> On Wed, Dec 24, 2014 at 4:27 PM, Johannes Schl=C3=BCter
> <johannes@schlueters.de> wrote:
>> On Wed, 2014-12-24 at 11:13 -0700, Levi Morrison wrote:
>>=20
>>> I'm asking for specific things. The reason is that some API's do a
>>> non-zero error code; the fact that they are negative is a detail =
that
>>> we should not need to care about.
>>=20
>> My guess is that positive values more often might have a meaning ("5
>> items changed", "address 0x1234") whereas negative values less often
>> have a meaning. Also passing -1 as parameter is more often invalid. =
Thus
>> passing -1 is making debug output look more suspicious.
>>=20
>>        (while there are  cases where -1 is valid, see recent famous =
pid
>>        =3D fork(); /* ... */ kill(pid, SIGKILL); issue)
>=20
> I don't think this is the same use case as SUCCESS and FAILURE. Many
> functions have an out parameter which is only valid when the returned
> value is SUCCESS. This is not the same thing as an API which returns
> an integer and just happen to embed error state in the negative range.
> Notably, it doesn't make sense to do `strpos() =3D=3D SUCCESS` to =
check
> success; these are different cases. My question is specifically
> directed at the ones that use SUCCESS and FAILURE: which ones require
> FAILURE to be negative instead of the normal UNIX-ism of non-zero?
>=20
> For the record I am in favor of an enum such as `zend_status` or some
> other name which indicates whether an operation succeeded or not for
> the reasons already cited in this thread. I just don't see why FAILURE
> needs to be negative and want to know why this is the case.

Hi Levi,

Again, I think the reason FAILURE is -1 is for consistency with other =
functions which use negative return values on error. Some functions =
return negative error codes, others just -1. Some functions return =
useful positive values, others just 0. But the idea is that all =
functions return a negative number on error, so you can use if (foo() < =
0) to check for errors. That=E2=80=99s the point of making FAILURE be =
-1, AIUI. It makes it consistent with other things, like fork() or =
strpos().

Thanks.

--
Andrea Faulds
http://ajf.me/