Synchronized Classes and Struct Members

[Benjamin Thaut]

Am 25.10.2011 08:06, schrieb Andrew Wiley:
> Geez, I try to write some multithreaded code and I just keep hitting these:
> --------
> module test3;
>
> struct SomeData {
> int i;
> int iPlus2() {
> return i + 2;
> }
> }
>
> synchronized class Bob {
> private:
> SomeData _dat;
> public:
> this() {
> _dat.i = 3;
> }
> @property
> int i() {
> return _dat.iPlus2(); // test3.d(22): Error: function
> test3.SomeData.iPlus2 () is not callable using argument types () shared
> }
> }
> --------
>
> This seems like it should be legal because SomeData is a value type.
> Accessing _dat.i directly is legal, and _dat can't possibly be shared.
> If I'm understanding things correctly, transitive shared shouldn't apply
> to value types like this, so the type of "this" when calling iPlus2
> should just be SomeData.

It can't be garantueed that a pointer to _dat is not given away at some 
point in the program. For example you could have a clas Foo that 
inherits from Bob and has a getter for _dat. Then it wouldn't be correct 
anymore to sasume _dat is unshared. Because of that it has been decided 
that trying to figure out if _dat has to be shared or not will not 
happen, thus its just shared always. I've already reported this some 
time ago and essentially it makes synchronized classes useless for me. I 
usually just write a normal class and but the synchronized blocks in 
myself. Also I use __gshared ;-)

-- 
Kind Regards
Benjamin Thaut