Is Python your only programming language?

sismex01 at hebmex.com sismex01 at hebmex.com
Thu Aug 14 16:40:07 CEST 2003


[Nick Vargish]
> > So what programming language actually does bridge the gap between
> > "thousands of lives depend on the code working right" and "getting
> > this up and running quickly"?

[Van Gale]
> I think that Ada is one of the few languages capable of being used on 
> "lives depend on it" systems.  It's not anything special about the 
> language in particular, but rather the immense amount of 
> man-hours and time spent in writing checking and analysis tools.
> That includes tools that can verify an Ada program will meet real-time 
> requirements.  This kind of tool is really sophisticated (obviously)
> and would probably be impossible to code for anything but a strong
> static typed language.

Coincidently, there's a thread like this on comp.lang.forth, and
precisely Ada was brought out as an example of a created-for-correctness
language; but one of the problems with this is brittleness.

As an example, someone mentioned the Arianne accident, a few years
back, which was "caused" by a Zero-division error caught by the
code, which raised some kind of error condition (I don't do Ada).

BUT, it seems that the segment of code being checked wasn't even
going to be executed (something about horizontan acceleration),
and since the rocket was already in the air, that code shouldn't
have mattered; "if it was C, then the operation would have silently
failed, and the rocket would have kept flying".

It's not really a criticism against Ada, but bad systems design/
implementation; for those cases where lives are at stake, or rocket
sciences ;-) , you need code coverage tools, extensive unit tests,
etc... so that absolutely NO untested code lines get into the system.

anyhow...

-gustavo


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