Just another example of missing string interpolation

[Walter Bright]

On 10/17/2023 7:39 PM, Adam D Ruppe wrote:
> On Wednesday, 18 October 2023 at 02:19:21 UTC, Walter Bright wrote:
>> I don't see how, from my reading of the proposal.
> 
> The first example under the Description shows this exact situation and then goes 
> on to explain how and why it works as expected.

The line in question:

```
writeln(__header, "I ate ", apples, " apples and ", bananas, " bananas totalling 
", apples + bananas, " fruit.")
```

What does writeln() do with __header?


> Things work correctly with this proposal, you either get the expected results or 
> a compiler error, as a natural consequence of the existing type system. Nothing 
> needs to be spelled out about this as there are not any special cases.

Does that mean writeln() gets rewritten to handle __header? If so, ok, but the 
YAIDIP doesn't say that.

Today, the only difference between writef() and write() is the former takes the 
first argument as the format string. Is this a fatal error? I suppose you could 
consider it as one, but that's an issue typical with variadic functions.


> Already did, over an hour ago.

Ok, I saw it after I posted that.

> It took about 30 seconds to specify. This isn't a 
> big deal. (And btw, even if it didn't specify, the behavior is well-defined in 
> the D Programming Language, and such things are already similar in other places, 
> including other existing compiler hooks, see _d_cmain 
> <http://dpldocs.info/this-week-in-d/Blog.Posted_2022_07_18.html>.
> 
> But now the text does specify the fully qualified name anyway, so this is all moot.

I think we're misunderstanding each other. What I am asking about is how does 
the user specify his own custom implementation of InterpolatedExpression?