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

[Jason M. <ko...@gm...>]

Henri Häkkinen wrote:
> Somebody mentioned in the OpenGL forums that we should avoid the use 
> of anonymous structures. Is this worth the concern?
>
> For example, compare these:
>
> typedef struct GLMmat2f_s {
>   union {
>     GLfloat m[4];
>     struct GLMmat2fdata_s {
>       GLfloat m00, m01, m10, m11;
>     };
>   };
> } GLMmat2f;
>
> vs.
>
> typedef struct {
>   union {
>     GLfloat m[4];
>     struct {
>       GLfloat m00, m01, m10, m11;
>     };
>   };
> } GLMmat2f;
>
> We need to enclose the mXX variables into a struct in order for the 
> union to take them as a whole.
>
> -- 
> Henri 'henux' Häkkinen
I would suggest that those struct definitions violate the design 
principle of /simplicity/. You need to pick one: either a matrix is an 
array of floats or it is a struct with member fields. It should not be 
both. If you're having to use a /union/, you've already done something 
wrong. Unions are confusing and scary to neophyte programmers.

I'd prefer that a matrix were defined as:

typedef GLfloat[4] GLMmat2f;

It's simpler and gets the job done without being confusing to a 
programmer as to what is going on. Yes, it will need to have conventions 
associated with it, but that's a small price to pay for the obviousness 
of what the matrix is doing.