First Draft: opUnwrapIfTrue

[Richard (Rikki) Andrew Cattermole]

On 08/05/2026 12:44 AM, Per Nordlöw wrote:
> On Thursday, 26 February 2026 at 13:53:41 UTC, Richard (Rikki) Andrew 
> Cattermole wrote:
>> The DIP: https://gist.github.com/ 
>> rikkimax/21242118e3bc1bf5f28024c2cdc33557
> 
> I really want this. I believe a new distinct syntax that triggers the 
> call to `opUnwrapIfTrue` is needed. My suggestion is something that 
> involves the question mark symbol. For instance,
> 
> ```d
> if (auto value ?= result) {}
> ```
> 
> or
> 
> ```d
> if (auto value =? result) {}
> ```
> 
> . Alternatively, what about extending the `foreach` to allow
> 
> ```d
> foreach (auto value; result)
> ```

You need the else branch of an if statement for this feature to be used 
in all cases.

Foreach statements are non-starters.

> when
> 
> ```d
> typeof(result).opUnwrapIfTrue
> ```
> 
> exists? A bit longer to type, though.

What I came up with is to require a call to that function i.e. through 
an alias called say unwrap.

```d
if (auto v = wrapper.unwrap)
```

However I want to disallow the call to opUnwrapIfTrue in any other 
circumstances and I have no found a way to do so that makes me happy.

Over all I think its better to drop this usage syntax requirement entirely.
No other language has it.