Something needs to happen with shared, and soon.

[Jason House]

On Monday, 12 November 2012 at 02:31:05 UTC, Walter Bright wrote:
>
> To make a shared type work in an algorithm, you have to:
>
> 1. ensure single threaded access by aquiring a mutex
> 2. cast away shared
> 3. operate on the data
> 4. cast back to shared
> 5. release the mutex

This is a fairly reasonable use of shared, but it is bypassing 
the type system. Once shared is cast away, it is free to be mixed 
with thread local variables. Pieces can be assigned to non-shared 
globals, impure functions can stash reference, weakly pure 
functions can mix their arguments together, etc... If locking 
converts shared(T) to bikeshed(T), I bet some of safeD's logic 
for no escaping references could be used to improve things.

It's also interesting to note that casting away shared after 
taking a lock implicitly means that everything was transitively 
owned by that lock. I wonder how well a library could 
promote/enforce such a thing?