On 6/14/21 11:09 AM, Jalil David Salamé Messina wrote:
I'm searching for a way to do something like this in D:
```cpp
struct MyStruct {
const size_t length;
int *const data;
MyStruct(size_t n) : length(n) {
data = new int[length];
}
}
```
This way it is mutable, but non resizeable:
```cpp
MyStruct s = MyStruct(10);
s.data[0] = 42; // Valid
s.data = new int[20]; // Error: assignment to const
```
Doing some extra reading about the theme I found the section on [Type
Qualifiers](https://dlang.org/spec/const3.html), which makes me believe
that the "tail constness" of D will disallow this kind of behavior.
My solution would be overriding the `[]` to make MyStruct behave as an
array and hiding the implementation details, but if you have a more
elegant solution I'm all ears!
D doesn't have head-const. So you must hide the mutable implementation
to get this to work.
You'd want to do this anyway, since you don't want to directly use the
pointer for anything like indexing (it should first validate the index
is valid, at least in an assert).
-Steve
