On Saturday, 24 October 2015 at 13:18:26 UTC, Shriramana Sharma
wrote:
Hello. I had first expected that dynamic arrays (slices) would
provide a `.clear()` method but they don't seem to. Obviously I
can always effectively clear an array by assigning an empty
array to it, but this has unwanted consequences that `[]`
actually seems to allocate a new dynamic array and any other
identifiers initially pointing to the same array will still
show the old contents and thus it would no longer test true for
`is` with this array. See the following code:
import std.stdio;
void main()
{
int a[] = [1,2,3,4,5];
int b[] = a;
writeln(a);
writeln(b);
//a.clear();
a = [];
writeln(a);
writeln(b);
}
which outputs:
[1, 2, 3, 4, 5]
[1, 2, 3, 4, 5]
[]
[1, 2, 3, 4, 5]
How to make it so that after clearing `a`, `b` will also point
to the same empty array? IOW the desired output is:
[1, 2, 3, 4, 5]
[1, 2, 3, 4, 5]
[]
[]
... and any further items added to `a` should also reflect in
`b`.
D's arrays are not pure reference types, they work like `struct
Array(T) { size_t length; T* ptr; }` with some extra methods and
operators. If you think of them like that it should be clear what
is/isn't possible.
If you want to have two references to the same array, including
the length, use T[]* or a ref argument to a function or wrap it
in a class.
