[Insight-developers] Proposal: Changing NumericTraits of vector types to use macros

Mon Nov 30 11:26:02 EST 2009

Le 30 nov. 09 à 16:24, Bradley Lowekamp a écrit :

> Hello Gaetan,
>
> The way you used just one macro for the different traits was very  
> nicely done. I had not done that.
>
> Two important differences with your implementation are:
>
> 1) The ElementTraits are public types. I am not sure that these are  
> needed for the interface, and may just be an implementation detail.  
> But if we actively want them as part of the interface that is fine.  
> I was going to make them private so as not to add more confusion to  
> the NumericTraits interface.
>

Yes, good idea. I remove the function

   Self max( const Self & )
   Self min( const Self & )

which were in RGBAPixel traits already, because the where in none of  
the traits I was working on, and doesn't seemed directly useful - I  
think they come from the numeric traits of VariableLength vector, so  
we may want to readd them to uniformize all the numeric traits.

> 2) Your macro only uses the total template specialization, where as  
> the other implementation conditionally uses partial template  
> specialization, so that on most compilers large sized arrays could  
> be used even though they were not totally specialized.

I tried to reproduce as exactly as possible what was already there,  
but with some macros. I was not confident enough in how the  
specialization is handle in all those compilers to reproduce exactly  
what is done in RGBAPixel for example.

If you are more comfortable than me on that subject, it would be great  
to do it your way!

>
> An Additional point, I have, is that OneValue() and ZeroValue should  
> be changed to not use then static member variables. There are two  
> reasons for this:
> 1) with partial specialization, there may not be a defined member  
> variable location, by initializing it in the function we can get  
> around this
> 2) in many cases the compilers are smart enough to optimize away  
> certain numeric when the value is known at compile time (inlined in  
> the function).
>

OK, good points - I thought that it may be more efficient that way,  
but it seems that I was wrong :-)

Gaëtan

> Brad
>
>
> On Nov 30, 2009, at 4:38 AM, Gaëtan Lehmann wrote:
>
>>
>> Brad, Luis,
>>
>> I have already commited some code on that subject, while working on  
>> two long standing bugs in wrapitk - the missing NumericTraits while  
>> building with dimension 4, and the empty NumericTraits< FixedArray<  
>> * > > classes.
>>
>> I've modified some macros from RGBAPixel numeric traits to refactor  
>> the numeric traits of FixedArray, Vector, CovariantVector and  
>> SymmetricSecondRankTensor.
>>
>> Regards,
>>
>> Gaëtan
>>
>>
>>
>> Le 28 nov. 09 à 18:09, Luis Ibanez a écrit :
>>
>>> Hi Brad,
>>>
>>> Yes, it is a good idea to propagate the use of Macros for other  
>>> NumericTraits.
>>>
>>> We took a historical detour in the development of the  
>>> NumericTraits, and
>>> only come to use the convenience macros with the most recently added
>>> classes. It will be great to back-port this practice to the  
>>> initial vector-like
>>> classes.
>>>
>>> As you pointed out, using the macros will result in more  
>>> consistent and
>>> maintainable code.
>>>
>>>
>>>   Luis
>>>
>>>
>>> ---------------------------------------------------------------------------
>>> On Fri, Nov 27, 2009 at 11:16 AM, Bradley Lowekamp
>>> <blowekamp at mail.nih.gov> wrote:
>>>> Hello,
>>>> The next logical step after adding itk::NumericTraits<long long>  
>>>> is to also
>>>> add it to all the vector types that also have numeric traits
>>>> defined. Unfortunately I am lazy, and manually going through all  
>>>> these
>>>> files, and close to 5,000 lines of code, to perform copy, paste,  
>>>> edit seems
>>>> like too much work.
>>>> Looking at itkNumericTratisVariableLengthVectorPixel.h:
>>>> http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Common/itkNumericTraitsVariableLengthVectorPixel.h?revision=1.7&root=Insight&view=markup
>>>> This seems to have an elegant macro which both does total template
>>>> specialization and partial specialization when needed. It seems  
>>>> like much
>>>> less work to implement similar macros in each file. One important  
>>>> change I'd
>>>> make to similar macros for other types is to make the  
>>>> "ElementTypes" (which
>>>> are needed for bcc) private so as to not add additional traits  
>>>> that have not
>>>> been defined as part of the interface.
>>>> As a "good" side effect, this will help maintainability and  
>>>> correct errors
>>>> that currently exist in the traits. For example  the many numeric  
>>>> traits for
>>>> for char vector types still have the char vector type as the  
>>>> PrintType,
>>>> which is wrong because it'll print ASCII value instead of  
>>>> numbers. There are
>>>> also missing trait types in many vector types as well. For  
>>>> example the
>>>> CovariantVector traits are missing the FloatType.
>>>>
>>>> Brad
>>>>
>>>> ========================================================
>>>>
>>>> Bradley Lowekamp
>>>>
>>>> Lockheed Martin Contractor for
>>>>
>>>> Office of High Performance Computing and Communications
>>>>
>>>> National Library of Medicine
>>>>
>>>> blowekamp at mail.nih.gov
>>>>
>>>>
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>>
>> -- 
>> Gaëtan Lehmann
>> Biologie du Développement et de la Reproduction
>> INRA de Jouy-en-Josas (France)
>> tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
>> http://voxel.jouy.inra.fr  http://www.itk.org
>> http://www.mandriva.org  http://www.bepo.fr
>>
>
> ========================================================
> Bradley Lowekamp
> Lockheed Martin Contractor for
> Office of High Performance Computing and Communications
> National Library of Medicine
> blowekamp at mail.nih.gov
>
>

-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr  http://www.itk.org
http://www.mandriva.org  http://www.bepo.fr

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