What are the prominent downsides of the D programming language?

[mw]

On Tuesday, 29 September 2020 at 20:29:49 UTC, jmh530 wrote:
> On Tuesday, 29 September 2020 at 18:38:29 UTC, mw wrote:
>> [snip]
>>
>> Good to hear, I opened an discussion issue here:
>>
>> https://github.com/jll63/openmethods.d/issues/19
>>
>> Anyone who's interested in the implementation, let's continue 
>> the brain storming there.
>
> You might recall that back in June I wrote [1] that D does not 
> have the ability to properly disable base members and member 
> functions, which would make implementing Eiffel-like semantics 
> significantly easier as part of the base language.
>
> [1] 
> https://forum.dlang.org/post/tpwwzkvcarqquqslspul@forum.dlang.org

Yes, I remember that. That approach is still trying to somehow 
trick / patch (e.g. via some form of opDispath) the current D 
object system.

The LISP (CLOS) multi-methods approach is different: basically, 
you build the dispatch mechanism yourself; so everything is under 
the libraries' control.

This is essentially how openmethods.d Multiple Dispatch is done.