• chmike (12/12) May 28 2016 In my long quest to implement a flyweight pattern with objects
• Meta (6/19) May 28 2016 Not currently. However, there was a proposal to remove monitors

chmike <christophe meessen.net> writes:

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 ? 

Meta <jared771 gmail.com> writes:

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