On Fri, Mar 2, 2018 at 12:20 PM, Chris Angelico <ros...@gmail.com> wrote:
> How often do you have a loop like this where you actually want to > capture the exact condition? I can think of two: regular expressions > (match object or None), and socket read (returns empty string on EOF). > This simplified form is ONLY of value in that sort of situation; as > soon as you want to add a condition around it, this stops working (you > can't say "while do_something() is not _sentinel as x:" because all > you'll get is True). And if you are looking for one specific return > value as your termination signal, you can write "for x in > iter(do_something, None):". > For me, it's all the time. Our geometry modeling database is hierarchical, so you see things like this all over kernel, often with a lot more code than just that one line calculating the cumulative scale factor: >>> scale = self.scale >>> parent = self.parent >>> while parent: >>> scale *= parent.scale >>> parent = parent.parent # The DRY part that I don't like... which would turn into >>> scale = self.scale >>> parent = self >>> while parent.parent as parent: >>> scale *= parent.scale
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