Re: LUA_USE_APICHECK

[liam mail <liam.list@...>]

On 26 August 2011 10:21, Josh Simmons <simmons.44@gmail.com> wrote:
> On Fri, Aug 26, 2011 at 7:05 PM, liam mail <liam.list@googlemail.com> wrote:
>> On 26 August 2011 09:50, Josh Simmons <simmons.44@gmail.com> wrote:
>>> On Fri, Aug 26, 2011 at 5:58 PM, liam mail <liam.list@googlemail.com> wrote:
>>>> I am just looking for some clarification when using the macro
>>>> LUA_USE_APICHECK, is it the case that indicators in the manual are not
>>>> respected for functions when using this macro? I ask because I decided
>>>> to turn the option on and run unit tests on OOLua to find that an
>>>> assert is being triggered for the function lua_touserdata (indirectly
>>>> via index2addr) with it, yet the manual states "'-' means the function
>>>> never throws any error". The situation under test was trying to pull a
>>>> user data of an empty stack which as I understood it would return NULL
>>>> and does without the macro, this situation is handled gracefully in
>>>> the test but means I can not use the macro as is. Firstly because an
>>>> assert (from assert.h) in unit tests is bad and also it would require
>>>> different tests for release and debug builds.
>>>>
>>>> Thanks
>>>> Liam
>>>>
>>>>
>>>
>>> I suggest checking the stack height before trying to remove things from it.
>>>
>>
>> There is no need to check the stack depth as it will return NULL as it
>> should when the macro is not used.
>>
>>> Errors in this instance refer to Lua errors, not any kind of C
>>> assertions or error handling.
>>
>> Yet it does say any error, which is why I ask the question.
>>
>> Liam
>>
>>
>
> Just because it returns what you think it should does not mean it's a
> valid API usage. Popping off an empty stack is using an invalid stack
> index (http://www.lua.org/manual/5.1/manual.html#3.2) and is therefore
> not sane API usage.
>
It returns what the manual says
"If the value at the given acceptable index is a full userdata,
returns its block address. If the value is a light userdata, returns
its pointer. Otherwise, returns NULL"
The index is neither an acceptable index, full or a light userdata
therefore it must return NULL.

> Error when used in the reference manual refers to Lua Errors
> (http://www.lua.org/manual/5.1/manual.html#2.7) specifically, not
> general failure.
>
>

Again sorry to point this out but "any error".

Liam