Python for air traffic control?

Ken Seehof kens at sightreader.com
Wed Jul 4 01:07:31 CEST 2001


For liability reasons, I can't give you advice on whether or not to
use python for an air traffic control application :-)

However, if I were (hypothetically, of course) to give you advice,
it would be the following, of which your reading constitutes an
agreement that I am not responsible for injury, deaths, and property
damage resulting from that which would be my advice, were it not, 
if fact, hypothetical, which it is.

Seems to me that python would be a good choice.  You can write
bugs in any language, including python.  However, python bugs
tend to be less subtle and easier to detect and fix than C/C++ bugs.

The lack of type checking and function prototyping is not nearly as
big of a problem (if it's a problem at all) as C++ programmers tend
to fear.

This fear is due to the fact that in some statically typed languages
such as C++, an undetected type mismatch is likely to cause rather
horrible bugs which are often intermittent and often corrupt unrelated
data.

These kinds of type mismatch bugs that C++ programmers are
terrified of (memory overwrites, etc.) simply do not exist in python at
all.  Python doesn't ever need to infer the addresses of bytes of data
from dubious type information at runtime (as C++ does).  Type
information is always stored within the objects themselves.

In python, data of the wrong type is not really any worse than data
of the wrong value, so these kinds of bugs tend to only have local
effects which are easily caught when tested.  Not surprisingly, I have
found that I usually get fewer type related bugs in Python than in C++.

Saying that python is unreliable because it lacks type checking is like
saying fish cause pollution because they lack bicycles.

- Ken

-- Disclaimer: The hypothetical opinions expressed above do not
necessarily represent my own opinions.

----- Original Message ----- 
From: "William Park" <opengeometry at yahoo.ca>
To: "Russ" <18k11tm001 at sneakemail.com>
Cc: <python-list at python.org>
Sent: Monday, July 02, 2001 2:52 PM
Subject: Re: Python for air traffic control?


> > From: Russ (18k11tm001 at sneakemail.com)
> > Subject: Python for air traffic control?
> > Date: 2001-06-29 17:42:45 PST
> >
> > I am thinking about using Python for a unique safety-critical
> > application in air traffic control. It will monitor a few hundred
> > aircraft for conformance to assigned trajectories, and it will
> > initiate an automatic alarm (for both controller and pilot) if an
> > aircraft deviates from its assigned trajectory and is in danger of a
> > collision. (The trajectory and tracking data will come from existing
> > C/C++ programs.) The software must be as simple, clean, and robust as
> > humanly possible. The default languages here are C/C++, but I am
> > toying with the idea of using Python instead. However, I am a bit
> > nervous about the lack of type checking and function prototyping,
> > among other issues. Is Python up to this task? Thanks for your
> > insights.
> 
> Of course, you idiot...  It depends how well you did in high school
> math.  If there are N airplanes whose positions are given by
>     (x,y,z)_i, i=1,2,...N
> then you have to calculate distance from an airplane at to every other
> airplanes.
> 
> You would be maintaining NxN table to see 
>     - if any position is outside the assigned trajectory, or
>     - distance (between any two position) is too close
> 
> Am I missing something?
> 
> -- 
> William Park, Open Geometry Consulting, <opengeometry at yahoo.ca>
> 8 CPUs cluster, (Slackware) Linux, Python, LaTeX, Vim, Mutt, Sc.
> 
> -- 
> http://mail.python.org/mailman/listinfo/python-list





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