Synchronized methods in D2

[Jonathan M Davis]

On Saturday 04 September 2010 12:06:23 Era Scarecrow wrote:
> > I'm currently porting a D1 code base to D2 which has the
> > following class
> > hierarchy:
> > 
> > interface Map
> > {
> >       void clear ();
> > }
> > 
> > class Hashtable : Map
> > {
> >      synchronized void clear () {};
> > }
> > 
> > class HashMap : Map
> > {
> >      void clear () {};
> > }
> > 
> > When I compiler the code I get an error about the "clear"
> > method in
> > Hashtable not being covariant with the "clear" method in
> > Map. Any
> > suggestions how I could solve this, preferable working in
> > D1 as well?
> 
>   I remember reading about this; The signatures have to match EXACTLY for
> it to work. The interface is a declaration of a contract, of what it
> expects. If a part of the contract is broken, an error tells you where to
> fix it.
> 
>  Even if technically it would be compatible, the compiler and type checking
> won't allow it. So either synchronize your interface as well, or drop it
> from the implementation.
> 
>  A third option, is to match the declaration, and have a private function
> that is synchronized that is called from clear. At least, i believe this
> is right.
> 
>  Era

Also, according to TDPL, either your _entire class_ is synchronized, or none of 
it is. So, synchronized really belongs on the class, not the function, and I 
wouldn't expect it to compile if only a portion of your functions are 
synchronized (though I don't know how close the current dmd is to TPDL with 
regards to synchronized).

- Jonathan M Davis