I can share non shared things?

Steven Schveighoffer schveiguy at yahoo.com
Tue Jun 19 20:39:40 UTC 2018


On 6/19/18 4:09 PM, gdelazzari wrote:
> So, let's say I have this code
> 
> https://run.dlang.io/is/CaMJjd
> 
> It doesn't compile, and that makes sense since myNotSharedObject is... 
> not shared. So I can fix it by making the class shared and making a 
> shared instance of it, like this
> 
> https://run.dlang.io/is/hoMFD1
> 
> And that's how shared is supposed to work, right? Cool, I like it.
> 
> But then I try this and... it compiles and runs?
> 
> https://run.dlang.io/is/mNQsH1
> 
> Or, even worse, even this compiles and runs https://run.dlang.io/is/oyzHcw
> 
> So, if I can share non-shared variables/objects/whatever, then what's 
> the point of shared?

Using Thread directly like that, you can override shared when passing 
data around. It's because natively, pthreads (or whatever threading 
system) doesn't care about shared, so it's on you to make sure you use 
it correctly.

Note that before TDPL, shared was this "new undefined" concept, even in 
D2, and Thread existed in D1 where there was no shared concept.

If you want full shared guards, use std.concurrency only.

-Steve


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