Tuples, CTFE, and Sliding Template Arguments

[Steven Schveighoffer]

On Saturday, 13 January 2024 at 03:59:03 UTC, Timon Gehr wrote:
> On 1/13/24 04:36, Walter Bright wrote:
>> 
>> I don't know what "interpolate an expression sequence" means. 
>> As for things getting out of sync, execi() with CTFE can 
>> reject a mismatch between format specifiers and arguments.
>
> Oh, not at all.
>
> ```d
> import std.stdio;
> alias Seq(T...)=T;
> void main(){
>     writefln(i"$(Seq!(1,2)) %s");
> }
> ```

Yes, and there is more:

```d
writefln(i"is it here? ${}(1) Or here? %s");
```

Bottom line is that if we make `%s` special, then all functions 
must deal with the consequences. There is not a format specifier 
you can come up with that is not easily reproduced in the string 
literal directly -- you have to escape it and *know* that you 
must escape it. The easier path is just not to deal with format 
specifiers at all -- tell the library exactly where the pieces 
are.

And by the way, your example brings up another point not recently 
brought up where 1036e handles and DIP1027 does not: tuples as 
interpolated expressions. Because each expression is enclosed by 
`InterpolatedLiteral` pieces, you can tell which ones were 
actually tuples.

-Steve