Re: generics fun
Re: generics fun
- Subject: Re: generics fun
- From: Lachlan Deck <email@hidden>
- Date: Sat, 26 Jul 2008 14:26:23 +1000
On 23/07/2008, at 2:43 AM, Mike Schrag wrote:
This is worth watching if you are wanting to learn more about using
generics (and enums):
http://www.youtube.com/watch?v=pi_I7oD_uGI
That's a great video ...
So I have a method which returns a batch of raw records like so:
(a) public Map< String, NSArray< NSDictionary< String, Object >> >
nextBatch();
and elsewhere I've got a method like so (according to PECS)
(b) public NSArray<Foo> faultRecordsForRawRows(String entityName,
NSArray<NSDictionary<String,? extends Object>>);
Guess what: the results of 'a' cannot be passed to 'b'.
// so we end up having to drop the typing like so:
for ( String entityName : currentRawBatch.keySet() )
{
// Note the following works but doing NSArray<NSDictionary<String,?>>
doesn't.
NSArray< ? > rawRecords = currentRawBatch.get( entityName );
<..>
// and then do a cast for which I have to suppress warnings
NSArray<Foo> foos = controller.faultRecordsForRawRows( ( NSArray<
NSDictionary< String, ? extends Object >> )rawRecords, entityName );
...
}
So that's a bit annoying. As I understand it it's not the done thing
to have return values that 'extend' something. So is there any other
suggestions?
with regards,
--
Lachlan Deck
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