how to assign to shared obj.systime?

Steven Schveighoffer schveiguy at
Mon Jul 13 01:46:01 UTC 2020

On 7/11/20 6:15 AM, Arafel wrote:
> Because the system don't know if just this lock is enough to protect 
> this specific access. When you have multiple locks protecting multiple 
> data, things can become messy.


> What I really miss is some way of telling the compiler "OK, I know what 
> I'm doing, I'm already in a critical section, and that all the 
> synchronization issues have been already managed by me".

You do. It's a cast.

> Within this block, shared would implicitly convert to non-shared, and 
> the other way round, like this (in a more complex setup with a RWlock):
> ```
> setTime(ref SysTime t) shared {
>      synchronized(myRWMutex.writer) critical_section {  // From this 
> point I can forget about shared
>          time = t;
>      }
> }
> ```

This isn't checkable by the compiler.

You could accidentally end up referencing shared things as unshared when 
the lock is unlocked. If you remove shared, you need to know and 
understand the consequences, and the compiler can't help there, because 
the type qualifier has been removed, so it's not aware of which things 
are going to become shared after the lock is gone.


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