Le 10/12/2015 00:58, Emil Dotchevski a écrit :
On Wed, Dec 9, 2015 at 3:41 PM, Vicente J. Botet Escriba < vicente.botet@wanadoo.fr> wrote:
Le 09/12/2015 13:43, Agustín K-ballo Bergé a écrit :
On 12/8/2015 1:25 PM, Phil Endecott wrote:
Adam Wulkiewicz wrote:
The formal review of Emil Dotchevski's QVM library begins today on 7th Dec and ends on 16th Dec. Full documentation is also viewable on Github: http://zajo.github.io/boost-qvm/
I find most of the identifiers too short. To give just a couple of examples: "transp" is used to mean "transpose". You save typing three letters, and get confusion with transparent, transport, etc. Then look at the names of some traits classes; elsewhere we have type_traits, allocator_traits, iterator_traits etc. all spelt out in full, but in qvm we have q_traits, v_traits and m_traits. I could go on but really almost every identifier is too short for my tastes.
I used an earlier version of the library several years ago, back when it was called "Boost.LA", and I found extremely short identifiers to be a concern too. I could understand going for `mat` and `vec` instead of `matrix` and `vector`, but not just `m` and `v`. For pretty much every other identifier, I would like to see a full blown word instead.
I'm not sure we need the prefix nor the suffix. The operations shouldn't have the type on its name. If the operation depends on a concept (vector, matrix, quaternion) and the operation has no parameter of this type the function should have the type as parameter
What would be wrong replacing
float vmag = mag(v); float33 m = rotx_m<3>(3.14159f); vref(v,YXZ) = rotx_m<3>(3.14159f) * v;
by
int mag = magnitude(v); float33 m = rotate_x<M3>(3.14159f); ref(v).YXZ() = rotate_x<M3>(3.14159f) * v;
Let me point out first that in this library q always means quaternion, m always means matrix, and v always means vector. With that in mind, could rotx_m<3> be misinterpreted?
Secondly, the semantics of rotx_m are different from what you're imagining. It does *not* return a "proper" matrix object, it returns a reference to its argument reinterpreted as an unspecified non-copyable 3x3 matrix type, which essentially allows the passed angle (3.14159f) to participate as a 3x3 matrix in QVM operations without creating a temp. That's why when instantiating the rotx_m template you specify the dimensions but not the type of the matrix (of course you can assign the result to any compatible matrix type.)
I'm really not a fan of the old operator% and now operator, syntax.
To me, (v,XY) looks like you're forming a row-vector with two elements. Is there a reason why these accessors can't be written with function syntax, i.e. XY(v) ? Or, for matrices, something like element<4,2>(m) rather than (m,A<4,2>) ?
The precedence issues are so bad with `operator,` that one has to pretty much always wrap it in parens, that makes all precedence issues go away. I think for that reason it's a better choice than `operator%`, that mostly just works and bit me over and over again. There are reasons against it too, for instance a missing include, a typo, a shadowing variable will turn a swizzling expression into a regular comma expression.
That said, if I have to write `(v,XY)` instead of `v.XY` I'd rather write `XY(v)` instead.
Clearly the operator, is too controversial.
Isn't
qvm::ref(v).XY()
terse enough?
Compared to (v,XY)?
The best is the enemy of the good. I requested if it is not terse enough. Vicente