On Wed, 27 Jul 2011 15:48:24 -0400, Asger Dam Hoedt <[email protected]>
wrote:
Hey
I've very recently started playing around with D, but I seem to have hit
my
head against a bug in dmd. I want to create a Vector class templated with
its dimension. This works fine until I try to overload the + operator
for my
vector and use it. I then get the error
Error: incompatible types for ((vec) + (vec)): 'Vector!(3)' and
'Vector!(3)'
I've boiled it down to a small example
struct Vector(int D) {
float es[D];
public:
this(immutable float x, immutable float y, immutable float z) {
es[0] = x; es[1] = y; es[2] = z;
}
Vector!(D) opBinary(string s)(immutable Vector!(D) rhs) if (s ==
"+") {
Vector!(D) ret;
for(int i = 0; i < D; ++i)
ret.es[i] = es[i] + rhs.es[i];
return ret;
}
}
alias Vector!(3) Vector3;
void main() {
Vector3 vec = Vector3(0,1,2);
vec = vec.opBinary!("+")(vec); // This works fine
vec = vec + vec; // This line fails miserably
}
If I replace the template argument in for the argument rhs with 3, then
everything works, but that's not really a nice solution :)
Is it me trying to use templates in a way they aren't meant to be used
or is
this a bug in dmd? If it is a bug, does anyone have an idea how to solve
this? I wouldn't mind fixing it in dmd myself, I just need some
guidelines.
It is a bug, someone just brought up almost exactly this problem in
d.learn.
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learn&article_id=28455
The proper workaround (and actually, the cleaner solution) is to use
Vector and not Vector!D. Inside a template, the name of the template is
the same as if you invoked the template with the same template parameters.
If you actually do need a different value for D, I'm not sure what works.
-Steve
