On Thursday, 30 January 2014 at 12:50:34 UTC, John Colvin wrote:
On Thursday, 30 January 2014 at 10:43:55 UTC, Ary Borenszweig
wrote:
Hi,
I just read this nice article about slices:
http://dlang.org/d-array-article.html
So I tried this code to see if I understood it correctly:
---
import std.stdio;
void main() {
auto a = new int[5];
auto b = a;
a[0] = 1;
for(auto i = 0; i < 100; i++) {
a ~= 0;
}
a[0] = 2;
writefln("a[0] = %d", a[0]);
writefln("b[0] = %d", b[0]);
}
---
This prints:
a[0] = 2
b[0] = 1
That is, "a" was resized to a point where it needed to
reallocate its contents. "b" still holds a reference to the
old data. When, after the for loop, I change a's data, b's
data doesn't change.
Is this expected behaviour?
How can I safely pass around a dynamic array without being
afraid someone will keep an old copy of the data?
pass the array by ref, or make a wrapper struct that holds a
pointer to a slice, or a wrapper class that holds the slice.
Alternatively, make a wrapper struct that disallows the append
operator and always use std.array.refAppender
woops, sorry that last one doesn't help.
