On Thursday, 5 September 2013 at 13:50:59 UTC, Timon Gehr wrote:
Why? I cannot spot any syntax I wouldn't get used to quickly in
this example. (AFAIK the @ are going away in favour of a
library solution with more verbose syntax though.)
In D something similar would look like this:
struct BodyWorld(N, LV, AV, M, II, CM){
World!(N, Body!(N, LV, AV, M, II), Constraint!(N, LV, AV,
M, II)) world;
BodyForceGenerator!(N, LV, AV, M, II)* forces;
BodySmpEulerIntegrator!(N, LV, AV, M, II)* integrator;
BodiesBodies!(N, LV, AV, M, II, BF!(N, LV, AV, M, II))*
detector;
IslandActivationManager!(N, LV, AV, M, II)* sleep;
SweptBallMotionClamping!(N, LV, AV, M, II, BF!(N, LV, AV,
M, II))* ccd;
JointManager!(N, LV, AV, M, II)* joints;
AccumulatedImpulseSolver!(N, LV, AV, M, II, CM)* solver;
}
Afaics there is not much of a difference. Arguably, having the
identifiers conveniently aligned to the left is actually a
slight advantage of rust's syntax.
Of course, the code contains a certain amount of duplication I
wouldn't really want to write down, and this could be improved
in D:
struct BodyWorld(N, LV, AV, M, II, CM){
private alias Args = Seq!(N, LV, AV, M, II);
World!(N, Body!Args, Constraint!Args) world;
BodyForceGenerator!Args* forces;
BodySmpEulerIntegrator!Args* integrator;
BodiesBodies!(Args, BF!Args)* detector;
IslandActivationManager!Args* sleep;
SweptBallMotionClamping!(Args, BF!Args)* ccd;
JointManager!Args* joints;
AccumulatedImpulseSolver!(Args, CM)* solver;
}
Just looking at the code, it looks very dense. The multiple
nested <> brackets (D was right to get rid of these) and the @mut
really bog down the code (I am aware that @mut has been moved to
a library solution now). Like I said, Rust coders no doubt get
used to parsing and understanding the different symbols, but to
an outsider it's a lot to take in. Note that this is only one
example. I found several other instances such as this in the
codebase that were difficult to make sense of at first. The thing
that trips me up the most, I think, are the lifetimes.
