On 10/21/2015 07:40 AM, Timon Gehr wrote:
On 10/21/2015 12:55 PM, Andrei Alexandrescu wrote:
On 10/19/15 9:49 PM, Jonathan M Davis wrote:
On Monday, 19 October 2015 at 23:37:09 UTC, Timon Gehr wrote:
This is the worst part:
class C{
int[] x=[1,2,3];
}
void main(){
auto mut=new C;
auto imm=new immutable(C);
assert(imm.x[0]==1);
mut.x[0]=2;
assert(imm.x[0]==2);
}
Oooo. Ouch. Yeah, that pushes it from being a good idea to disallow this
in order to avoid bugs to a necessity to disallow it in order to avoid
breaking the type system.
Please file, thanks. -- Andrei
(I've filed it in 2013.
https://issues.dlang.org/show_bug.cgi?id=10376 .)
What should be the expected behaviour?
- Don't allow default initialization with mutable indirections in
aggregates.
- Clone the mutable referenced data for each instance.
- Have different "init" for different mutability.
- ... ?
The quickest way to stop the bleeding is to disallow the code. It's
incorrect for immutable data and misleading for mutable data. (What an
user might expect is that each data comes with a distinct array.)
I can't believe I didn't know about this huge hole.
Andrei
