On Mon, 07 Nov 2011 07:59:08 -0500, bearophile <[email protected]>
wrote:
Jonathan M Davis:
The errors that you're running into are completely by design.
I see, thank you for your (and Steven's) answers.
Isn't it possible to see unassigned constant array attributes as mutable
just inside their struct/class constructor (and allow the code I've
shown)? It's handy because often I just need to initialize them in the
constructor, and later I don't need to change them any more.
-------------------------
Steven Schveighoffer:
Line 8 is invalid, because a const member is only allowed to be
initialized *once* in a constructor.
Is this a DMD bug then (this compiles and runs)?
const struct Foo {
const int y;
this(in int x) pure {
y = x;
y = x + x;
}
}
void main() {
auto f = Foo(5);
}
I would say yes, though I supposed the compiler may be able to take leeway
and prove that the y = x line is not needed.
If it compiles at all, I think it would be implementation defined.
In the following program Foo1 and Foo2 are not allowed, while Foo3 is
allowed. Is this a good design? They seem similar enough cases to me.
const struct Foo1 {
const int[1] a;
this(in int x) pure {
a[0] = x; // Error
}
}
const struct Foo2 {
const int[1] a;
this(in int x) pure {
a = [x]; // Error
}
}
const struct Foo3 {
const int a;
this(in int x) pure {
a = x; // OK
}
}
void main() {}
I agree all of these should be valid. I think the ever-impressive Kenji
Hara is working on that case.
-Steve
