Proposed Changes to the Range API for Phobos v3

[Steven Schveighoffer]

On Thursday, 16 May 2024 at 14:56:55 UTC, Jonathan M Davis wrote:

> 5. Forward ranges will no longer have save. Rather, it will be 
> required that copying a forward range will result in an 
> independent copy. Both the original and the copy must then have 
> the same elements in the same order, and iterating one will not 
> affect the other. So, in essence, copying a forward range must 
> be equivalent to calling save (though the actual implementation 
> could be more clever than that).

So something I just thought of as a drawback here -- `save` gives 
a nice explicit mechanism to copy when passing to a function that 
takes a value by `auto ref`. In other words it *forces* non-ref 
semantics so you do not affect the original.

Since passing to an `auto ref` function lets the compiler decide 
to not make a copy, code that currently uses `save` for this 
purpose doesn't have an equivalent in the new regime.

If we aren't going to have it, we might want to add a specialized 
do-nothing UFCS function which just takes an lvalue and turns it 
into an rvalue. Maybe we just call it `save`! Or maybe just a 
boring `asRvalue`...

-Steve