So what does (inout int = 0) do?

[Andrei Alexandrescu via Digitalmars-d]

On 04/15/2016 06:50 AM, Kenji Hara via Digitalmars-d wrote:
>
>
> You should recall the history of inout.
> http://wiki.dlang.org/DIP2
>
> At first, It has designed to temporarily squash mutable/const/immutable
> qualifiers on function argument inside function body. Therefore when
> inout qualifier appears in function return type, but doesn't on
> parameter types, we defined it an error.
>
> However, I concluded that we can remove the restriction. When an inout
> object arises from thin air, no one holds the qualifier of its real
> instance. It means, the returned inout object can be converted to
> arbitrary qualifiers without type system breaking.
>
> Two years ago I opened an enhancement issue:
> https://issues.dlang.org/show_bug.cgi?id=13006
>
> And posted a pull request.
> https://github.com/D-Programming-Language/dmd/pull/3740

I do recall the history. The enhancement is sensible in a frame of mind 
"we need to keep inout" but I'm looking at top level and thinking, crap 
we can put up with a little duplication if we get rid of inout. It's 
just a prime example of apparently simple idea gone bonkers.

In all of my recent code I've avoided inout and didn't miss it one bit. 
There's no need for it - I replace it with one-liners that forward to 
template functions, which in turn deduce qualifiers and all is great.

Andrei