[Insight-developers] Modes versus Objects

[Bill Lorensen]

The dashboard should not get this red in the first place. It shows a
breakdown/weakness in our process.

With our tools there is no way it should have gotten this red.



On Thu, Jun 2, 2011 at 11:46 AM, Luis Ibanez <luis.ibanez at kitware.com> wrote:
> Bill,
>
> Yeap,
>
> We need more of these guiding principles,
>
> and
> we need to capture them somewhere in the Wiki,
> so they are available for quick reference when
> we are making code changes.
>
> Something along the lines of what we have in:
>
> http://www.itk.org/Wiki/ITK_Coding_Style_Guide
> http://www.itk.org/Wiki/ITK_Code_Review_Check_List
>
> Otherwise,
> it is easy to settle for the quickest solution
> that let the Dashboard go back to green.
>
> Here is a first cut at that new Wiki
> page on Design Principles:
>
> http://www.itk.org/Wiki/ITK_Design_Principles
>
>
> and it is now linked from:
> http://www.itk.org/Wiki/ITK_Policies_and_Procedures
>
>
>     Luis
>
>
> ------------------
> On Thu, Jun 2, 2011 at 11:32 AM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>> Folks,
>>
>> This discussion is motivated by recent activity...
>>
>> Back in the early days of OO programming, I recall having discussions
>> about the use of modes versus objects. When I taught OO courses I
>> always discouraged modes if they changed the "identity" of the object.
>>
>> Should a mode be used to change the behaviour of an object or should a
>> new object be created?
>>
>> A case where a mode is better than an object:
>> Controlling the visibility of an actor in VTK:
>>  1) Mode: vtkActor VisibilityOn/Off
>> or
>>  2) Object: two classes vtkActor and vtkVisibleActor
>>
>>  1) is the appropriate solution since, at run time, an application
>> may want to change the visibility of an actor.
>>
>> A case where an object may be better than a mode:
>>  1) Mode: itkShiftScaleImageFilter
>> SetOperationOrderToShiftScale()/SetOperationOrderToScaleShift()
>> or
>>  2) Object: two classes itkShiftScaleImageFilter and itkScaleShiftImageFilter
>>
>>  A VTK approach versus an ITK approach
>>  1) mode: vtkImageMathematics 21 different modes (ADD,SUBTRACT,MULTIPLY,...)
>>  2) object: itkAddImageFilter, itkSubtractImageFilter,
>> itkMultipleImageFilter...
>>
>> It is not always obvious as to the best choice. But, I think the
>> question should be asked anytimne we introduce a new "mode".
>>
>> Bill
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>