Difference between __gshared and shared.

[Jonathan M Davis via Digitalmars-d]

On Wednesday, 8 July 2015 at 13:26:53 UTC, Shachar Shemesh wrote:
> On 08/07/15 15:08, Jonathan M Davis wrote:
>> I know that there are a number of people who get frustrated 
>> with shared
>> and using __gshared instead, but unless you fully understand 
>> what you're
>> doing and how the language works, and you're _really_ careful, 
>> you're
>> going to shoot yourself in the foot it subtle ways if you do 
>> that.
>>
> I guess my main issue with this statement is that I don't see 
> how that is not the case when using shared.

Because unless you cast away shared, you're prevented from doing 
much of anything to the object, and the compiler clearly 
indicates which objects are shared, so the code that has to worry 
about getting locks right and dealing with casting away shared 
correctly is clearly marked and segregated from the rest of the 
program, unlike with a language like C++ or Java where 
_everything_ is shared, and you have no idea which objects are 
actually shared across threads and which are thread-local.

What we have is uglier than we'd like, but that ugliness 
highlights the small portion of code where you actually have to 
deal with synchronization and threading issues so that if you do 
have a problem with it, you have a very small amount of code to 
dig through to figure out how you screwed it up.

- Jonathan M Davis