On 19.04.2016 14:07, Jeff Thompson wrote:
On Tuesday, 19 April 2016 at 11:43:22 UTC, Anonymouse wrote:
On Tuesday, 19 April 2016 at 10:41:05 UTC, Jeff Thompson wrote:
I want to create a mutable array of immutable objects, but the code
below gives the error shown below. It seems that "new
immutable(C)[1]" makes the entire array immutable, but it seems I
should be able to change the elements of an array of pointers to an
object even though the objects are immutable. How to do that?
class C {
this(int x) immutable { this.x = x; }
int x;
}
void main(string[] args)
{
auto array = new immutable(C)[1];
array[0] = new immutable C(10); // Error: Cannot modify immutable
expression array[0].
}
Mind that this is akin to declaring a string (immutable(char)[]) and
trying to modify an element.
You can append, though. Or rather, make a new array/slice with the new
elements concatenated into it.
Thanks but then I'm confused as to why the following code is allowed. It
is a mutable array of immutable strings.
mutable array of mutable strings, actually. immutable(string)[] would be
a mutable array of immutable strings.
I can modify the array but not
the elements they point to. What's so special about a string?
string is not a class. It is an alias for immutable(char)[].
Why can't I do that with my own class?
...
D has no built-in way to express it.
There is https://dlang.org/phobos/std_typecons.html#.Rebindable.
