On Feb 1, 2020, at 09:59, David Kastrup <d...@gnu.org> wrote:
>
> even with a reference parameter. Of course this does not "really" give
> an indication about this being in-out, but neither does &variant.
That's an important point. What indicates that a parameter is _not_ an
out-parameter is "const". You might happen to have that near enough to the
call site to be helpful.
const Foo& foo = ...;
int mp = calc_midpoint (foo);
Where you don't have that, and you want to leave no doubt that a function does
not modify your object, you can declare a separate const reference and pass
that, or you can use a convenience function like std::as_const from C++17,
Foo foo;
string s = to_string (ly::as_const (foo));
...
return calc_midpoint (foo); // might modify foo
I hope that that example makes as_const and "might modify foo" look like the
result of an overabundance of caution. I don't mean to suggest that as_const
or comments should be dictated in situations like this anymore than I think
that passing out-parameters as pointers should be dictated.
--
Dan
