On 2010-09-05 02:18, Jonathan M Davis wrote:
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
Ok, that is good to know.
--
/Jacob Carlborg
