Slice/Substr [0..?lastIndexOf(".")] How refer itself without create a variable?

[Andrea Fontana]

On Thursday, 5 December 2019 at 11:28:51 UTC, Marcone wrote:
> Simple example:
>
> writeln("Hi\nHow are 
> you?\nGood".splitLines()[0][0..?lastIndexOf(r"\")]);
>
> How to refer to this string in lastIndexOf() without create a 
> variable?
>
> Thank you.

One solution:

     writeln(
         "Hello\nHow are you?\nGood"
         .splitLines()
         .map!(x => x[0..x.lastIndexOf("o")])
     );

But be careful: lastIndexOf could be < 0 if string is not found.