Re: [Glsdk-devel] The use of anonymous structures

[H. H. <hen...@gm...>]

See this link,

http://msdn.microsoft.com/en-us/library/bb172573(VS.85).aspx

In Direct3D they are using similar design.



On Sun, Aug 24, 2008 at 4:55 AM, Henri Häkkinen <hen...@gm...> wrote:

>
>
> On Sun, Aug 24, 2008 at 4:53 AM, Henri Häkkinen <hen...@gm...>wrote:
>
>>
>>
>> On Sun, Aug 24, 2008 at 4:44 AM, Jason McKesson <ko...@gm...>wrote:
>>
>>>  Henri Häkkinen wrote:
>>>
>>>
>>>
>>> On Sun, Aug 24, 2008 at 4:19 AM, Jason McKesson <ko...@gm...>wrote:
>>>
>>>>  Henri Häkkinen wrote:
>>>>
>>>> Does anyone have anything to say on this, please? I am currently working
>>>> hard on the GLM and I think we should resolve the issue of how we actually
>>>> define the math types.
>>>>
>>>>  Well, the VC++ compiler issue pretty much ends #2 as a possibility. If
>>>> #1 doesn't work for you, that leaves #3.
>>>>
>>>
>>> Well no, this is not true at all. The VC compiler issues is only about
>>> anonymous structures. For example, this generates a warning:
>>>
>>> typedef struct GLMvec2f_s {
>>>   union {
>>>     GLfloat v[2];
>>>     struct {
>>>       GLfloat x, y;
>>>     }
>>>   };
>>> } GLMvec2f;
>>>
>>> While this does not:
>>>
>>> typedef struct GLMvec2f_s {
>>>   union {
>>>     GLfloat v[2];
>>>     struct GLMvec2fcoords_s {
>>>       GLfloat x, y;
>>>     }
>>>   };
>>> } GLMvec2f;
>>>
>>>   Admittedly it's been a while since I last used pure C, but if I'm
>>> reading that right, to access the x or y members, I would need:
>>>
>>> GLMvec2f someValue;
>>>
>>> someValue.GLMvec3fcoords_s.x = 0.5f
>>>
>>> This is a pretty clear violation of design goal #2: Simplicity. And if
>>> the inner struct can't be accessed with a simple ".x", then what's the point
>>> in having it at all?
>>>
>>
>> No that is not correct at all.
>>
>> There is a difference between the name of the structure and the name of
>> the variable. When you write in C like this:
>>
>> struct FOO {
>>   int baz;
>> } fizban;
>>
>> You access baz inside the struct like this:
>>
>> fizban.baz = 12;
>>
>> When we have the vector type:
>>
>> typedef struct GLMvec2f_s {
>>   union {
>>     GLfloat v[2];
>>     struct GLMvec2fcoords_s {
>>       GLfloat x, y;
>>     };
>>   };
>> } GLMvec2f;
>>
>> You access it normally;
>>
>> GLMvec2f v;
>> v.x = 10.0f;
>>
>> The 'GLMvec2fcoords_s' is a structure name, nor a variable name.
>>
>
> TYPO: s/nor/not/
>
>
>>
>>
>>
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>>
>>
>> --
>> Henri 'henux' Häkkinen
>>
>>
>
>
> --
> Henri 'henux' Häkkinen
>
>


-- 
Henri 'henux' Häkkinen