On Sunday, 25 September 2016 at 04:54:31 UTC, grampus wrote:
Dear all
For example, I have a struct
struct point{int x;int y}
point a;
Is there an easy way to access x and y by using a["x"] and
a["y"]
I guess I need to overload [], but can't figure out how.
Someone can help? Thank you very much
You can't do that. There's a problem because the string passed is
not known at compile-time, so the return type of "opIndex(string
member)" cannot be inferred.
It works only for one type:
°°°°°°°°°°°°°°°°°°°
import std.stdio;
struct Something
{
int x,y;
float z;
int opIndex(string member)
{
alias T = typeof(this);
foreach(m;__traits(allMembers, T))
if (m == member)
{
static if (is(typeof(__traits(getMember, T, m)) ==
int))
return __traits(getMember, T, m);
}
assert(0);
}
}
void main(string[] args)
{
Something s;
writeln(s["x"]);
}
°°°°°°°°°°°°°°°°°°°
If you add a template parameter to opIndex then you can't call it
with the array syntax so it becomes pointless to use an operator
overload.
