Re: Contracted exceptions for Ada

On Mon, 10 Dec 2007 20:25:34 +0000, Simon Wright wrote:

The Ariane IV system engineers said to themselves, and probably in the
design documentation, "The maximum horizontal velocity is X. Therefore
the conversion to the fixed-point type _Whatever_ cannot
overflow. Therefore we do not need to handle exceptions for this
conversion, so (given we are short of CPU power) we will not do any
extra processing to avoid exceptions."

Not sure they would have recognised "contract" in that context.

Yes, my premise was that the type of H_Input changed from Ariane IV to
Ariane V. In this case translation of the conversion function
H_Input_To_Whatever could refute the second "therefore" because X would not
be the maximal possible value of H_Input anymore.

My point is that the fault could be detected (assuming that
conversion was in Ada), under the condition that the compiler vendor
would not make the same mistake while porting the compiler... (:-))

Not if there was no port, and the exact same hardware with the exact
same software was reused! (I'm not sure if that was in fact the case)

You mean that the ADC was reused as well? In that case (just speculating of
course) the compiler could detect the problem already for Ariane IV,
noticing that the range of H_Input is not bound by X and forcing to add an
exception handler somewhere.

--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
.

Relevant Pages

  • Re: Is this the Right way TO release COM interface ?
    ... COM compiler support wrappers actually preserve ... It's not so clean to undo the conversion. ... changing the retval parameter to the return type and adding exceptions, then absolutely use the wrapper classes. ... Are you saying that there's an option to request #import to generate code that doesn't translate HRESULTs into exceptions? ...
    (microsoft.public.vc.language)
  • Re: Contracted exceptions for Ada
    ... "The maximum horizontal velocity is ... Therefore the conversion to the fixed-point type _Whatever_ ... do any extra processing to avoid exceptions." ...
    (comp.lang.ada)
  • Re: Contracted exceptions for Ada
    ... "The maximum horizontal velocity is ... Therefore the conversion to the fixed-point type _Whatever_ ... do any extra processing to avoid exceptions." ...
    (comp.lang.ada)
  • Re: pre-check for string-to-number conversion
    ... > I am reading an ASCII data file and converting some of the strings to ... I know that I can us exceptions, ... > conversion, but I can't figure out how to do it. ... but note that this won't except valid floats like '1e10'. ...
    (comp.lang.python)
  • Re: writeObject signature
    ... > or the compiler must do a cast to Object. ... Java refers to a syntax for type conversion -- namely, ... it would be wrong (or bad design) to ...
    (comp.lang.java.programmer)