[netCDFJava #KSI-560385]: Generics in ucar.ma2

(ignore previous)

On 8/25/2011 11:14 AM, address@hidden wrote:

hi george:
>
> Yet, I think there are a lot of possibilities in ucar.ma where it is possible 
> to use generics. 
>
> Make a new generic Class <T> Array
> Hold in this class empty arrays float [], short [], long [] etc.
> In constructor reflect type T.getclass() and initialize corresponding array .
>
> Another point is the dimensionality of the matrices. First of all, I wonder 
> that you are not making use of any 'final' statements. I think you should use 
> them whenever possible to improve performance. 

this is what they said to do in the early days, to avoid runtime class 
substitution.
then the hotspot compiler guys said this wasnt needed.
i havent actually done any timing on it for a long time.


> And then I wonder why you have implementation D0..D7 and not just use an 
> access-method with loops over their dimensions. A constructor Array(<T>, int 
> d) would initialize the final dimension.
At the time i was on the jsr for multidimensional arrays, and thats what the 
IBM guys insisted on.
i think the main effect is that one can optimize the stride index arithmetic 
when you know what the rank is.
again, i havent revisted the actual performance in many years, and compilers 
have changed a lot.

>
> And then the most delicate part has to be implemented, think about all the 
> methods, which parts of them are necessary (for example, I would prefer 
> omitting the getDouble(), getFloat() methods etc) and replace it by 
> getValue(), according to the initialized Array<T>), whenever there is 
> something type-specific in the code it probably can be replaced by T or ?.
that would be interesting!
>
> After all I would implement a new version with probably different API and 
> deprecate the old one. I hope that you are not frightened and think about it. 
> Letting the compiler do as much type-checking as possible is not a bad idea. 
> Maybe the code can be also reduced a lot.
> If you thought about it a while , please let me know!
it would be interesting to try a design based on your ideas, and see how it 
performed against current one, and against raw java arrays,

>
> Best regards,
> Georg
>
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: Unidata netCDF Java Support [mailto:address@hidden] 
> Gesendet: Freitag, 19. August 2011 18:12
> An: Steidl, Georg
> Cc: address@hidden
> Betreff: [netCDFJava #KSI-560385]: Generics in ucar.ma2
>
>
> Hi Georg:
>
> As you can tell, the Array classes preceded java generics. I use them 
> wherever I can, but I dont understand them deep enough to actually write 
> classes that implement them.
>
> So the short answer is i'd love to have you contribute to that. However, I 
> would guess that it would be hard to make this backwards compatible (?) If 
> so, I would have to think carefully about how/if we could do this, or if we 
> would need to make a new version with a different API.
>
> What do you think?
>
> John
>
>> Hello NetCDF-Developers!
>>
>> I am really glad that there are projects like NetCDF-Java that you have
>> created.  Since I got more familiar with Java Generics now I thought
>> whether you think about implementing ucar.ma2 and all the Array Stuff
>> with templates.
>>
>> Is there something planned? If yes, I would like to contribute to that.
>>
>> Regards,
>> Georg Steidl
>>
>> --
>> M.Sc. Comp. Engineering
>>
>> Deutsches Zentrum für Luft- und Raumfahrt e. V.  |   German Aerospace Center
>> Institut für Aerodynamik und Strömungstechnik    |   Institute of 
>> Aerodynamics and Flow Technology
>> Abteilung Hubschrauber                        |   Department Helicopters
>>
>> Lilienthalplatz 7, 38108 Braunschweig, Germany
>> Tel : +49 (0)531 295 3306
>>
>>
>>
>
> Ticket Details
> ===================
> Ticket ID: KSI-560385
> Department: Support netCDF Java
> Priority: High
> Status: Open
>
>
>
> Ticket Details
> ===================
> Ticket ID: KSI-560385
> Department: Support netCDF Java
> Priority: High
> Status: Open
> Link:  
> https://www.unidata.ucar.edu/esupport/staff/index.php?_m=tickets&_a=viewticket&ticketid=18590


Ticket Details
===================
Ticket ID: KSI-560385
Department: Support netCDF Java
Priority: High
Status: Open