[Insight-developers] Floating Point Exception Handling in ITK -- your feedback needed.

[Bill Lorensen]

Please fix the compile errors associated with your checkin.

On Wed, Jul 14, 2010 at 11:06 AM, kent williams
<norman-k-williams at uiowa.edu> wrote:
> I have an itk::FloatingPointExceptions class now that on OS X and Linux that
> turns on numerical exceptions.  It's simple enough on the outside, and not
> that complicated on the inside; but before I check it in I wanted to make
> sure that it passed stylistic muster with you lot.
>
> If you enable numerical exceptions with this class, the default behavior is
> to call abort().  This is consistent (I think) with the Borland 6 behavior.
>
> The SetExceptionAction method allows you to specify whether to call exit or
> abort when an exception is thrown.  This is only part of the class for the
> benefit of CTest:  You can have tests in CMake that pass only when the test
> returns non-zero (i.e. fails), but if a test program aborts, that counts as
> a test failure even if you set the property WILL_FAIL to TRUE for that test.
>
> This class, in a default Insight build, does nothing. You have to set
> ITK_USE_FLOATINGPOINTEXCEPTIONS to ON when you configure a build to turn on
> floating point exceptions.  If this CMAKE variable is turned off, there's no
> change at all to the ITK library's current behavior.
>
> The itkFloatingPointExceptions.cxx contains specific code for OS X Intel
> (tested), OS X PPC (not tested), Linux (tested), and Windows (not tested or
> fully implemented).
>
> The Windows code does turn on exceptions, but doesn't have a SIGFPE handler
> to exit or abort on exceptions.  I don't know if there's  a special  way to
> set this up on Windows, and don't have a Windows machine set up to build and
> test that.  I assume that implementing this on Windows would be
> straightforward, modulo Microsoft's usual obtuseness.
>
> The FloatingPointExceptions is a singleton -- its only members are static,
> and it can't be instantiated.
>
>
> /** \class itkFloatingPointExceptions
>  * Allows floating point exceptions to be caught during program execution.
>  */
> class ITK_EXPORT FloatingPointExceptions
> {
> public:
>  /** defines what should happen when exceptions occur */
>  typedef enum { ABORT, EXIT } ExceptionAction;
>  /** Enable floating point exceptions */
>  static void Enable();
>
>
>  /** Disable floating point exceptions. */
>  static void Disable();
>  /** Control whether exit(255) or abort() is called on an exception */
>  static void SetExceptionAction(ExceptionAction a);
>  /** Access current ExceptionAction */
>  static ExceptionAction GetExceptionAction();
> private:
>  FloatingPointExceptions(); // Not implemented.
>  FloatingPointExceptions(const FloatingPointExceptions&);  // Not
>                                                            // implemented.
>  void operator=(const FloatingPointExceptions&);  // Not implemented.
>  /** static member that controls what happens during an exception */
>  static ExceptionAction m_ExceptionAction;
> };
>
>
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