status of Programming by Contract (PEP 316)?

[Russ]

On Sep 1, 6:51 pm, al... at mac.com (Alex Martelli)

> try:
>   blah blah with as many return statements as you want
> finally:
>   something that gets executed unconditionally at the end

Thanks. I didn't think of that.

So design by contract *is* relatively easy to use in Python already.
The main issue, I suppose, is one of aesthetics. Do I want to use a
lot of explicit function calls for pre and post-conditions and "try/
finally" blocks in my code to get DbC (not to mention a global
variable to enable or disable it)?

I suppose if I want it badly enough, I will. But I also happen to be a
bit obsessive about the appearance of my code, and this does
complicate it a bit. The nice thing about having it in the doc string
(as per PEP 316) is that, while it is inside the function, it is also
separate from the actual code in the function. I like that. As far as
I am concerned, the self-test code shouldn't be tangled up with the
primary code.

By the way, I would like to make a few comments about the
"reliability" of Python code. Apparently I offended you the other day
by claiming or implying that Python code is inherently unreliable. I
think it is probably possible to write very reliable code in Python,
particularly for small to medium sized applications, but you probably
need top notch software engineers to do it. And analyzing code or
*proving* that a program is correct is technically harder without
static typing. In highly regulated safety critical domains, you need
more than just reliable code; you need to *demonstrate* or *prove* the
reliability somehow.

I personally use Python for its clean syntax and its productivity with
my time, so I am certainly not denigrating it. For the R&D work I do,
I think it is very appropriate. But I did raise a few eyebrows when I
first started using it. I used C++ several years ago, and I thought
about switching to Ada a few years ago, but Ada just seems to be
fading away (which I think is very unfortunate, but that's another
story altogether).

In any case, when you get right down to it, I probably don't know what
the hell I'm talking about anyway, so I will bring this rambling to a
merciful end.

On, one more thing. I see that the line wrapping on Google Groups is
finally working for me after many months. Fantastic! I can't help but
wonder if my mentioning it to you a few days ago had anything to do
with it.