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

Alex Martelli aleax at aleax.it
Tue Jan 11 18:43:48 CET 2005


On 2005 Jan 11, at 18:27, Michael Chermside wrote: ...

... but in my world, people violate Liskov all the time, even in languages that attempt (unsuccessfully) to enforce it. [1] ... [1] - Except for Eiffel. Eiffel seems to do a pretty good job of enforcing it.

...has Eiffel stopped its heroic efforts to support covariance...?
It's been years since I last looked seriously into Eiffel (it was one of the languages we considered as a successor to Fortran and C as main application language, at my previous employer), but at that time that was one of the main differences between Eiffel (then commercial-only) and its imitator (freeware) Sather: Sather succumbed to mathematical type-theory and enforced contravariance, Effel still tried to pander for how the human mind works by allowing covariance (which implies a Liskov violation and is probably the main serious reason for it) and striving horrendously to shoehorn it in. So what's the score now...?

Alex



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