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Date: Thu, 25 Dec 2014 15:38:52 +1100
Message-ID: <CAEZPtU531SuCzrUa4kNwMMn_kDut3zceDCoyADc4ZjU9rYqspQ@mail.gmail.com>
To: Xinchen Hui <laruence@php.net>
Cc: Andrea Faulds <ajf@ajf.me>, Levi Morrison <levim@php.net>, 
	=?UTF-8?Q?Johannes_Schl=C3=BCter?= <johannes@schlueters.de>, 
	PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] About SUCCESS/FAILURE
From: pierre.php@gmail.com (Pierre Joye)

On Thu, Dec 25, 2014 at 3:34 PM, Xinchen Hui <laruence@php.net> wrote:
> Hey:
>
> On Thu, Dec 25, 2014 at 12:06 PM, Andrea Faulds <ajf@ajf.me> wrote:
>>
>>> On 24 Dec 2014, at 23:53, Levi Morrison <levim@php.net> wrote:
>>>
>>> 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:
>>>>
>>>>> 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.
>>>>
>>>> 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. Th=
us
>>>> passing -1 is making debug output look more suspicious.
>>>>
>>>>        (while there are  cases where -1 is valid, see recent famous pi=
d
>>>>        =3D fork(); /* ... */ kill(pid, SIGKILL); issue)
>>>
>>> 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?
>>>
>>> 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 fu=
nctions which use negative return values on error. Some functions return ne=
gative error codes, others just -1. Some functions return useful positive v=
alues, 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 wit=
h other things, like fork() or strpos().
>>
>> Thanks.
> lets make this simple.
>
> first we need unify PHP self..

Exactly, and it is not like we can unify libc ourselves ;)


--=20
Pierre

@pierrejoye | http://www.libgd.org