On 07.05.20 09:38, Stephen J. Turnbull wrote:
Christopher Barker writes:> So while yes, alternate constructors are a common pattern, I don't > think they are a common pattern for classes like zip. That's a matter of programming style, I think. There's no real difference between zip(a, b, length='checksame') and zip.checksame(a, b) They just initialize an internal attribute differently, which takes one of a very few values.
The big difference between these two versions is about usability. A flag is convenient if the actual value is expected to be determined only at runtime so you can write `zip(a, b, length=length)`. A distinct function on the other hand emphasizes the expectation that this behavior is usually determined when the code is written; it would be awkward to write `getattr(zip, length)(a, b)`. Both this and the different behavior of zip-flavors speak in favor of the second, `zip.<mode>` version. One concern however is that `zip.checksame` looks like `checksame` is a convenience function of `zip` that doesn't necessarily perform any zipping; it could only perform the length check and return True or False. Sure, for general iterators this would not be very useful because they get consumed in the process but for someone who doesn't know the details this might not be as obvious. Maybe people start writing code like this: if not zip.checksame(a, b): raise ValueError() for stuff in zip(a, b): ... _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/VOLDNSQUXHCDYTPUQZBBMBKNZE7HKCFJ/ Code of Conduct: http://python.org/psf/codeofconduct/
