opIndex, opSlice, length for joiner?

[Maverick Chardet via Digitalmars-d]

On Friday, 22 January 2016 at 11:23:05 UTC, Jonathan M Davis 
wrote:
> Arguably, walkLength shouldn't even accept a range that isn't a 
> forward range, since if it's not, then walkLength is just going 
> to eat the range. As for calling save, there's no point. It's 
> too late as soon as you've passed the range into the function, 
> since that copied the range, which is undefined behavior due to 
> the fact that the exact semantics of copying a range vary 
> wildly depending on how a range is implemented. In generic 
> code, if you want to use a range after passing it to a 
> function, you have to call save and pass that to the function; 
> otherwise, you get undefined behavior when you do anything with 
> the range after passing it to the function.

Yes actually this was my point, why not forcing the range to be a 
forward range? The only advantage I see is that it allows to 
count the number of elements of an input range, but then I guess 
it would need to be mentioned in the documentation somewhere, 
what do you think?

Yes my code is wrong sorry about that, I was just trying to 
figure out how to force the saving in some way...