shared - i need it to be useful

[Timon Gehr]

On 22.10.18 02:45, Manu wrote:
> On Sun, Oct 21, 2018 at 5:35 PM Timon Gehr via Digitalmars-d
> <digitalmars-d at puremagic.com> wrote:
>>
>> On 21.10.18 20:46, Manu wrote:
>>>> Shared data is only useful if, at some point, it is read/written, presumably by
>>>> casting it to unshared in @trusted code. As soon as that is done, you've got a
>>>> data race with the other existing unshared aliases.
>>> If such a race is possible, then the @trusted function is not
>>> threadsafe, so it is not @trusted by definition.
>>> You wrote a bad @trusted function, and you should feel bad.
>>> ...
>>
>> I wonder where this "each piece of code is maintained by only one person
>> and furthermore this is the only person that will suffer if the code has
>> bugs" mentality comes from. It is very popular as well as obviously
>> nonsense.
>>
>>> The simplest way to guarantee that no unsafe access is possible is to
>>> use encapsulation to assure no unregulated access exists.
>>
>> This only works if untrusted programmers (i.e. programmers who are only
>> allowed to write/modify @safe code) are not allowed to change your
>> class. I.e. it does not work.
> 
> Have you ever cracked open std::map and 'fixed' it because you thought
> it was bad?
> Of course not. Same applies here. Nobody 'fixes' core.atomic.Atomic
> without understanding what they're doing.
> 

You are not proposing to let core.atomic.Atomic convert to shared 
implicitly, you are proposing to do that for all classes.

> You seem to be stuck on the detail whether you can trust the @trusted
> author though...

Again: the @safe author is the problem.