[Python-ideas] Pre-conditions and post-conditions

[Steven D'Aprano]

On Tue, Aug 21, 2018 at 09:06:54AM +0200, Marko Ristin-Kaufmann wrote:

> Is there any chance to introduce these constructs in the language or is it
> too small a feature for such a big change?

I don't think contracts is a small feature. I think it is a HUGE 
feature, but under-appreciated by most developers. (Probably due to 
unfamiliarity, and the difficulty in using it in a language with no 
syntactic support.)

Whether it is practical to add it to Python, I don't know. I suspect 
that we would have to develop some sort of third-party solution first, 
even if it did not do everything contracts ought to do (or do them less 
efficiently) as a proof of concept. PyContracts is probably a good place 
to start. For those who missed Wes' email:

https://andreacensi.github.io/contracts/

Cobra is another good place to look, as it demonstrates a 
nice syntax that reads like a cross between Python and Eiffel:

http://cobra-language.com/trac/cobra/wiki/Contracts





-- 
Steve