[SystemSafety] proofs

paul_e.bennett at topmail.co.uk paul_e.bennett at topmail.co.uk
Fri Nov 23 13:43:08 CET 2018


On 23/11/2018 at 11:52 AM, "Steve Tockey" <Steve.Tockey at construx.com> wrote:
>
>Paul,
>Are you familiar with “Design by Contract”? Much of what you are 
>talking about for abstract function-level behavior can be 
>expressed in Design by Contract form. The missing piece would be 
>artifacts of implementation choices (e.g., because an unsigned 
>short was used inside the function, a maximum of 128 things can be 
>supported).

I have heard of it, yes.

>It could be that a well-stated contract together with an explicit 
>statement of technical limits could be sufficient.

If all functions had such documentation, then the selection for software
component reuse is made simpler.

>The next question would be, “What about when the code is much 
>bigger than a single function?”

There is a clue to my preferred programming environment in everything
I post. The finer granularity I spoke of is because it is based on a truly
component oriented approach and, by ensuring that the documentation
standard is applied throughout, we get quite a good appreciation of what
we are using underneath any function we implement. That programming
environment is extensible by adding functions into the collective, so we
are always super-setting, rather than sub-setting.

Even the most complex application, in my preferred programming
environment, is constructed from the bottom up from using functions.
The lower order functionality can be fully proven before you add the next
layer. It is all about ensuring a solid foundation.

So far, the hardest part, for me, is ensuring that others, who write for the
same environment, follow the documentation guidelines to teh extent that
a documentation tool we use can peel the descriptive data into a file for
presentation purposes.

Scalability has never been a problem.

Regards

Paul E. Bennett IEng MIET
Systems Engineer
Lunar Mission One Ambassador
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