In my long quest to implement a flyweight pattern with objects instantiated at compile time, I was indirectly notified of the possible problem of synchronization.

In a flyweight pattern the user has the impression there are distinct instances where in fact objects with the same state (member variable value) are the same instance.

Since with play a trick with the users assumption, there is a high risk that user produces logically invalid code when using synchronization with such a flyweight object.

In order to avoid this problem I would need a solution to make synchronization impossible on an object ? It is preferable if this could be enforced at compile time. Is this possible with D ? 

On Saturday, 28 May 2016 at 16:24:21 UTC, chmike wrote:
> In my long quest to implement a flyweight pattern with objects instantiated at compile time, I was indirectly notified of the possible problem of synchronization.
>
> In a flyweight pattern the user has the impression there are distinct instances where in fact objects with the same state (member variable value) are the same instance.
>
> Since with play a trick with the users assumption, there is a high risk that user produces logically invalid code when using synchronization with such a flyweight object.
>
> In order to avoid this problem I would need a solution to make synchronization impossible on an object ? It is preferable if this could be enforced at compile time. Is this possible with D ? 

Not currently. However, there was a proposal to remove monitors from objects by default unless they have a special UDA on them, so if that change ever goes through it's as simple as not annotating your class.

https://github.com/dlang/druntime/pull/789