`return const` parameters make `inout` obsolete
Zach the Mystic via Digitalmars-d
digitalmars-d at puremagic.com
Mon Mar 16 12:03:27 PDT 2015
On Monday, 16 March 2015 at 16:22:46 UTC, Marc Schütz wrote:
> On Monday, 16 March 2015 at 14:17:58 UTC, Zach the Mystic wrote:
>> char* fun(return const char* x);
>> Compiler has enough information to adjust the return type of
>> `fun()` to that of input `x`. This assumes return parameters
>> have been generalized to all reference types. Destroy.
> That's a very interesting observation. I never liked the name
> `inout`, as it doesn't describe what it does. The only downside
> I see is that it's more magic, because nothing on the return
> type says its mutability is going to depend on an argument.
> I think Kenji also had additional plans for `inout`, related to
> uniqueness. There was a PR. Better ask him whether it's going
> to be compatible.
`return` would work just as well for uniqueness.
inout(T*) fun(inout(T*) x);
T* fun(return const T* x);
I don't think any information is being lost. My attitude is that
unless you are losing information, the underlying logic won't be
any harder to implement. I think that `return` parameters are a
building block of `inout`, but more useful because they can be
used separately from it. Perhaps in the early days of D, it just
seemed too weird to have `return` parameters, but now with ref
safety, they are better justified. But if they'd been there back
then, `inout` probably wouldn't exist, since you can just build
it in its current form from `const` and `return`.
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