On Monday, 19 November 2018 at 14:51:14 UTC, Steven Schveighoffer
wrote:
Or just use inout. This is literally what inout is for:
inout(q32) toQ32 inout {
return q32(x);
}
This should transfer whatever constancy of the original is used
for the return value.
Yep, I just wanted to explicitly point out the `this T`, which
gets overlooked way too often.
However, I'd state that this is really a workaround for a
language deficiency. In reality, I would surmise (without
knowing the implementation) that q32's state is a complete copy
of the q16 state. So there is no reason to apply any constancy
copying from the source to the destination.
The real problem is that mutating operators on struct rvalues
are always allowed, because `this` is always passed by
reference. For the most part this is a harmless drawback, but
because there is no way to "opt out" of this, you can't stop it
when it really doesn't make sense (as in this case).
Sure. At first I was perplexed why Dennis' a /= 2 even compiled.
Then I saw the alias this.
I have long wanted a way to direct IFTI how to define its
parameters base on the arguments. We have a simple adjustment
for arrays, where the array is always unqual'd before IFTI
define the parameter.
In other words:
const int[] arr;
void foo(T)(T t) {... }
foo(arr) => T = const(int)[], not const(int[])
I think Andrei in the last dconf proposed we do more of this
with other types (for ranges, specifically). But I think it
would be good to also define other conversions possibly
manually.
I agree completely. Like Dennis' code, or that gcd example from
Phobos, it'd really help to be able to be explicit in the
signature, not creative in implementation :) Especially
considering that Unqual is a high-yield type system nuke.
