[Python-Dev] PEP 246, redux (original) (raw)

Alex Martelli aleax at aleax.it
Wed Jan 12 16:50:55 CET 2005

On 2005 Jan 12, at 16:26, Guido van Rossum wrote: ...

[Alex]

I'm saying that if, by mistake, the programmer has NOT registered the A->C adapter (which would be easily coded and work perfectly), then thanks to transitivity, instead of a clear and simple error message leading to immediate diagnosis of the error, they'll get a subtle unnecessary degradation of information and resulting reduction in information quality. I understand, but I would think that there are just as many examples of cases where having to register a trivial A->C adapter is much more of a pain than it's worth; especially if there are a number of A->B pairs and a number of B->C pairs, the number of additional A->C pairs needed could be bewildering.

Hm? For any A and B there can be only one A->B adapter registered. Do you mean a number of A->B1, B1->C1 ; A->B2, B2->C2; etc? Because if it was B1->C and B2->C, as I understand the transitivity of PyProtocols, it would be considered an error.

But I would like to see some input from people with C++ experience.

Here I am, at your service. I've done, taught, mentored, etc, much more C++ than Python in my life. I was technical leader for the whole C -> C++ migration of a SW house which at that time had more than 100 programmers (just as I had earlier been for the Fortran -> C migration back a few years previously, with around 30 programmers): I taught internal courses, seminars and workshops on C++, its differences from C, OO programming and design, Design Patterns, and later generic programming, the STL, and so on, and so forth. I mentored a lot of people (particularly small groups of people that would later go and teach/mentor the others), pair-programmed in the most critical migrations across the breadth of that SW house's software base, etc, etc. FWIW, having aced Brainbench's C++ tests (I was evaluating them to see if it would help us select among candidates claiming C++ skills), I was invited to serve for a while as one of their "Most Valued Professionals" (MVPs) for C++, and although I had concluded that for that SW house's purposes the tests weren't all that useful, I did, trying to see if I could help make them better (more suitable to test real-world skills and less biased in favour of people with that "language-lawyer" or "library-packrat" kind of mentality I have, which is more useful in tests than out in the real world).

I hope I can qualify as a C++ expert by any definition.

C++ goes to great lengths to pick automatic conversions (which perhaps aren't quite the same as adaptations but close enough for this comparison to work)

I agree with you, though I believe PJE doesn't (he doesn't accept my experience with such conversions as a valid reason for me to be afraid of "close enough for this comparison" adaptations).

and combine them. In practice, is this a benefit or a liability?

It's in the running for the coveted "Alex's worst nightmare" prize, with a few other features of C++ - alternatively put, the prize for "reason making Alex happiest to have switched to Python and almost managed to forget C++ save when he wakes up screaming in the middle of the night";-).

Alex

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