Disabling opAssign in a type disabled all the opAssigns of an aliased type?
Steven Schveighoffer
schveiguy at gmail.com
Tue Jul 31 20:40:25 UTC 2018
On 7/30/18 2:30 PM, aliak wrote:
> Is this a bug?
>
> If not is there a workaround?
>
> I would like for the alias this to function as a normal A type unless B
> specifically disables certain features, but it seems weird that
> disabling one opAssign disables all of them inside the aliases type but
> not in the aliasing type?
>
>
> struct A {
> void opAssign(int) {}
> }
> struct B {
> A a;
> alias a this;
> @disable void opAssign(float);
> }
>
> void main() {
> B b;
> b = 3;
> }
>
> Error: function `onlineapp.B.opAssign` is not callable because it is
> annotated with @disable
>
OK, so one thing to learn in D, you can't hijack stuff. When you
override a function, you have to override ALL the overloads.
What you have done is defined opAssign as ONLY accepting a float, and
then disabling any calls to it.
This is obfuscated somewhat by the fact that 3 can be a float as well.
So even if you didn't disable the opAssign(float), it would still call
that function.
You can get around it by defining a forwarding function for the
overloads you want to let through:
@disable void opAssign(float);
auto opAssign(int x) { return a.opAssign(x); }
-Steve
More information about the Digitalmars-d-learn
mailing list