[Insight-developers] [Insight-users] INSIGHT JOURNAL: managedITK (ITK 3.8 ?)

Tue Jul 8 10:04:11 EDT 2008

Le 8 juil. 08 à 08:07, Dan Mueller a écrit :

> Hi Gaetan,
>
> (FYI: I have moved this discussion to the developers list).
>
> Firstly, thanks for your work on WrapITK. As you have surmised, at
> some point last year I took WrapITK and mangled it for my own
> purposes. There *are* a lot of similarities between the two projects,
> however there are also a number of differences (the biggest being the
> code generation as you have pointed out). I have a number of concerns
> regarding the integration of ManagedITK with the new WrapITK:
>
> 1. Code generation.
> To make my feelings clear, I do not want to use SWIG for the code
> generation of ManagedITK. SWIG C# code generation uses what is called
> P/Invoke, which is a lot less flexible than the "It Just Works"
> mechanism currently employed by ManagedITK. That said, if the new
> WrapITK will support other code generation mechanisms, then I do not
> foresee any issues moving the code generation make files to
> Languages/ManagedITK.

Yes, no swig on manageditk side is fine.

>
>
> 2. Refactoring.
> I have taken a brief look at the new WrapITK. Although you said it was
> designed to be reusable for something else than CableSWIG or SWIG, it
> seems there is still (significant?) refactoring work for this to
> become a reality. For example, it still assumes CableSWIG is required.
> As with many ITK developers, I do ITK stuff during my personal time,
> and therefore I have limited resources to spend on this particular
> project. How much help would you (and other ITK Developers) be
> providing to make the new WrapITK truly independent from SWIG? Or have
> I misinterpreted things?

There are only a few things to do to not require cableswig and swig  
anymore.
It hasn't been done yet, because both python and java requires it, but  
all the internal code is well separated. I can complete that part  
alone, as soon as I found a little time to work on wrapitk.

>
>
> 3. Wrapped types.
> As you pointed out, there are some types wrapped by one project and
> not the other. The main reason for this is that type conversion in
> ManagedITK (ie. native ImageRegion to "managed" ImageRegion) is
> performed manually (see Source/Common/itkManagedTypes.cxx). To support
> "complex" (real and imaginary) types for example, a manual mapping
> must be made between the native complex object and a managed object.
> Therefore, if these two projects come together, I feel there must be a
> mechanism to exclude some wrap_*.cmake files for ManagedITK. The same
> may be needed for WrapITK, which for example does not (currently)
> support mesh filters, and may not be able to in the same way as
> ManagedITK does.

Meshes are not supported because I know nearly nothing about them, and  
so I was not able to choose the relevant types to wrap.
Meshes support would definitely be a positive impact of manageditk on  
wrapitk.

Excluding some stuff in one language or the other is already  
implemented at the module level. It can be refined to fit all of our  
needs.

>
>
> 4. Module names.
> The module names *are* important for ManagedITK -- in the sense that
> each module is compiled as a separate *.dll. The Microsoft compiler
> can not handle putting all the files into a single dll. As such the
> dll names need to be meaningful so that users can intuitively find
> their filters. I do not think the WrapITK module names are intuitive.
> For example: how do you differentiate which filters are in
> "SimpleFilters" versus "Filtering"?

I don't differentiate them. I've never been pleased by the current  
module names.
There is for sure a big place for discussions on this side.

>
> 5. Underscore before template definition.
> This is not a problem. The underscore can be removed in ManagedITK to
> make it the same as WrapITK.

Or they can be used in wrapitk — it would make no difference in  
python, and can make things much clear in java and tcl.

>
>
> 6. Backwards compatibility.
> Does WrapITK fall under the same backwards compatibility policy as the
> rest of ITK? If so, I'm not sure I would be willing to concede on all
> the above points in order for ManagedITK to be integrated with
> WrapITK. However, if a middle ground could be found, then I think it
> may be possible to move forward.

WrapITK is marked as experimental, so I don't think it fall under the  
ITK's backward policy.
That being said, I tried to make things as backward compatible as  
possible in python, with deprecation warnings when required (and  
possible).

Currently, external projects may need some small changes to build with  
wrapitk unstable. Python code made for wrapitk stable runs without  
changes on wrapitk unstable, but produce some deprecation warnings.

>
>
> In summary:
> 1. It should be possible to move the code generation to the  
> Languages folder.
> 2. The new WrapITK needs to support wrapper generation without SWIG or
> CableSWIG.
> 3. There needs to be a mechanism to turn some wrapped types off and
> on, depending on whether WrapITK or ManagedITK, or other.
> 4. Module names are a point of contention for me. More discussion is  
> needed.
> 5. Underscores -- no problem.
> 6. Backwards compatibility must be a consideration as we plan the  
> next steps.

No major problem so — nice :-)

Gaëtan

>
>
> Cheers, Dan
>
> 2008/7/8 Gaëtan Lehmann <gaetan.lehmann at jouy.inra.fr>:
>>
>> Le 7 juil. 08 à 22:15, Gaëtan Lehmann a écrit :
>>
>>>
>>>>
>>>> Is there material that can be merged/shared with the other
>>>> wrappings ?
>>>
>>> Dan,
>>>
>>> I wanted to ask you the same question — Luis did it first :-)
>>>
>>> Despite you said that WrapITK is a "totally separate project",  
>>> ManagedITK
>>> has reused lot of code from WrapITK. Actually, they still share a  
>>> lot of
>>> code — a quick look at  managed_itkCastImageFilter.cmake, from  
>>> ManagedITK,
>>> and wrap_itkCastImageFilter.cmake would be quite convincing: they  
>>> even share
>>> the comments :-)
>>> They are not all as similar of course, so the question is:
>>>
>>> Would it be possible to avoid the current code duplication?
>>>
>>> The reason why I wanted to ask that question now, is because  
>>> WrapITK has
>>> made great progress in the last weeks. Some times ago, I began to  
>>> work on a
>>> pure swig implementation of WrapITK. The work was left unchanged  
>>> for a quite
>>> long time, but recently, Ali decided to work on the java part. His  
>>> work
>>> convinced me to work again on python part. At this time, wrapitk  
>>> unstable is
>>> nearly completed in python — I already began to use it for real  
>>> image
>>> analysis task, to benefit of the numerous improvements — and Ali  
>>> is using
>>> java part on his side. The code is available at:
>>>
>>> http://code.google.com/p/wrapitk/source
>>>
>>> In WrapITK unstable, I took care to completely separe the type
>>> declarations — in the wrap_*.cmake — and the language specific  
>>> code. The
>>> goal is to make all that hard job of defining template parameters  
>>> for type
>>> instantiation fully reusable for something else than wrapping with  
>>> cableswig
>>> or swig. The examples I had in mind were:
>>> * wrapping python with PyBoost
>>> * ExplicitITK
>>> * ManagedITK
>>>
>>> If you agree, I would be pleased to try to see with you a way to  
>>> merge
>>> ManagedITK and WrapITK.
>>
>>
>> After a bit of reading of ManagedITK code, I'm quite convinced that  
>> there is
>> some factorizing to do, and that it would benefit to both projects.
>> The big differences I see are:
>> * the code generator, of course very specific of ManagedITK
>> * the Common directory, which is specific of ManagedITK
>> * the wrapped types — some types available in WrapITK are not in  
>> ManagedITK
>> (complex types for example) and some in ManagedITK are not in  
>> WrapITK (RGBA
>> for example). It would be nice for both to have them :-)
>> * the modules names
>> * the managed property definitions
>> * the underscore before the template parameters in the instantiated  
>> name
>> * the external projects implementation
>>
>> Specific code is quite well separated, and some of the code  
>> specific of one
>> project would benefit to the other.
>> The only specific code mixed with generic code at this time is the  
>> managed
>> property definitions. I do think they can be quite nicely moved  
>> outside the
>> generic files, in the /Languages/Managed/Properties/ for example  
>> (to reuse
>> the wrapitk directory layout). Then, when END_WRAP_CLASS() is  
>> called in the
>> /Modules/*/wrap_*.cmake files, the content of corresponding  
>> managed_*.cmake
>> file can be read (if it exists), to define the properties for the  
>> current
>> classes.
>> That way, all generic code can be common to both projects, and  
>> specific code
>> is localized in a single subdirectory of the /Languages directory.
>>
>> The module names may be a problem depending on their importance in
>> ManagedITK.
>>
>> The rest looks much like details — underscore in name can be used  
>> in wrapitk
>> or can be manageditk specific without problem, and external project
>> shouldn't be that difficult to implement in one way or the other.
>>
>> Do you think this kind of organization for managed properties would  
>> fit your
>> needs?
>> There are surely many other problems — I hope they are not too  
>> difficult :-)
>>
>> Regards,
>>
>> Gaëtan
>>
>>
>> --
>> 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.mandriva.org
>> http://www.itk.org  http://www.clavier-dvorak.org

-- 
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.mandriva.org
http://www.itk.org  http://www.clavier-dvorak.org

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