mark readonly parameters as const

[recp]

see #83

[coveralls]

Coverage remained the same at 11.081% when pulling 14f06a2 on const into 120ae9a on master.

[acoto87]

I think it looks good. It's true that parameters that aren´t modified should be const to allow library users have const if they want.

How would this affect the struct implementation? Should struct parameters that aren´t modified be const as well?

[recp]

@acoto87 thanks for the review.

How would this affect the struct implementation? Should struct parameters that aren´t modified be const as well?

Yes I think it should be const, to prevent struct be copied in C++, we could do something like this:

CGLM_INLINE
mat4s
glm_mat4_mul(const mat4s CPP_REF a, const mat4s CPP_REF b)

it is similar to my comment (#83 (comment)) but alternative.

#ifdef __cplusplus
#define CPP_REF &
#else
#define CPP_REF
#endif

or maybe we keep focus on C and do this (C++ ref) in the future if needed

[acoto87]

Well it's your call if you want to support C++ features, but I think it would be better at the moment to keep it simple.

Yes I think it should be const, to prevent struct be copied in C++, we could do something like this:

Prevent copies when struct arguments are passed to functions is something you want to accomplish? In C the only way we have to do that is with pointers, right? Is that something you want to consider?

[recp]

It would be better to not copy structs if it is possible (it is possible in C++), since our structs are inline maybe compiler may not copy them, I'm not sure for certain. Personally I don't want to use pointers in struct params yet. Should it be pointer?

Let's keep it simple as you said for now and ignore what I said for C++, in the future we may support to move/ref if we want, it is not topic of today.