Something like ADL from C++?

[Derek Fawcus]

On Tuesday, 3 December 2024 at 19:34:21 UTC, Alexandru Ermicioi 
wrote:
> On Tuesday, 3 December 2024 at 11:55:50 UTC, Manu wrote:
>> Has anyone ever experimented with a pattern like this? 
>> Essentially, I can't work out how to expand /combine an 
>> overload set to include symbols from multiple imports....
>
> as a compromise you could have an uda that packs custom 
> serialisation defined on type itself or field of that type, 
> then you can make serializer employ it when it sees it 
> somewhere.

That is essentially what Go does for its serialisation (Marshal 
and Unmarshal) routines.

Only the public fields of a struct can be processed, and how to 
handle a field in a non default fashion is marked by an attribute 
- an extra string.

```Go
type DelSite struct {
     SiteID types.SiteID `json:"site-id" validate:"min=1"`
}
```

One of those is then encoded as follows, where 's' happens to be 
a struct ptr:

```Go
     var b []byte
     b, err := json.Marshal(s)
```

It is using run time reflection, but I see no obvious reason why 
compile time reflection could not be used instead, since that is 
what D has.