implicit construction operator

[biozic]

On Monday, 26 February 2018 at 19:25:06 UTC, WebFreak001 wrote:
> hi, I had an idea from using some C# which I think would be 
> really cool in D. Basically allow modifying implicit 
> construction of a type. Right now we only have struct 
> opAssign/constructor implicit conversion, but this addition 
> would also add it to classes and make it even more convenient.
> [...]
>
> What's your opinion on this? I think it is really useful to 
> have when interoping with scripting languages or doing 
> (de)serialization or for these attribute wrappers which are 
> there because of no function attribute UDAs. I was looking into 
> implementing this to dmd myself but the code on the implicit 
> cast checks looks a bit hardcoded for the types that are in 
> right now and not really suitable to implement this, but maybe 
> someone with more knowledge about dmd internals can do this 
> with ease.
>
> This is only a single direction T -> Wrapper and I think this 
> would actually be enough, but it would maybe be possible to add 
> @implicit to opCast in the future.

Such implicit conversion was once 'on the table', see this 
thread: 
https://forum.dlang.org/post/lv9iqs$1jp3$1@digitalmars.com.

I also think that controlled implicit conversion would be 
sometimes useful, notably with wrapper structs. For now, the only 
solution is to use templated functions (in some cases, all the 
code using wrapper structs has to be templated...). Pragmatism 
and cautious design sometimes defeat 'EVIL'.