[Understanding] Classes and delegate inheritance vs function pointers

[sighoya]

On Sunday, 10 January 2021 at 00:44:26 UTC, Q. Schroll wrote:

>
>   Car[] cars = ...;
>   Vehicle[] vehicles = cars;
>   vehicles[0] = new Boat; // err...
>   // cars[0] is a Boat now!?
>
> Now what? Do what Java does and throw an Exception? Or use 
> const to prevent mutation?

Yes, you are right:

```
Derived derived;
Base* bp=&derived;
*bp=base;
derived.method() //ouch
```

> I'm unsure what you mean.

I mean D doesn't support co(ntra)varaince out of the box, but 
seems allowing them in certain cases increasing the degree of 
confusion just as it is the case here.
I think it would be just better to generally incorporate 
co(ntra)variance into D's semantic or completely disregard it.