Worst ideas/features in programming languages?

[Atila Neves]

On Friday, 5 November 2021 at 21:22:12 UTC, victoroak wrote:
> On Friday, 5 November 2021 at 17:02:05 UTC, Atila Neves wrote:
>>
>>> - @safe `void` initialization
>>
>> For what types? It doesn't compile for pointers, for instance, 
>> and I don't see why void initialising an int would be unsafe.
>>
>>> - .init
>>
>> Because?
>>
>
> Well, I can't answer for him but `void` initialization and 
> `.init` makes it impossible to have any meaningful constraint 
> on a type. And some types may depend on these constraints to 
> maintain safety.
>
> ```d
> import std.stdio;
>
> struct LimitedInt(int min, int max)
> {
>     @disable this();
>
>     this(int number)
>     {
>         assert(number >= min);
>         assert(number <= max);
>         _number = number;
>     }
>
>     private int _number;
> }
>
> void main() @safe
> {
>     LimitedInt!(1, 1000) x = void;
>     auto y = LimitedInt!(1, 1000).init;
>     writeln(x);
>     writeln(y);
> }
> ```
>
> It's `@safe` in this example but there's no way to enforce 
> these constraints when you have those.

Interesting. Adding an invariant causes compilation to fail:

```
foo.d(27): Error: variable `foo.main.x` `void` initializers for 
structs with invariants are not allowed in safe functions
```