In article <545d76fe$0$12980$c3e8da3$54964...@news.astraweb.com>, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote:
> The following list comprehension and generator expression are almost, but > not quite, the same: > > [expr for x in iterable] > > list(expr for x in iterable) > > > The difference is in the handling of StopIteration raised inside the expr. > Generator expressions consume them and halt, while comprehensions allow > them to leak out. A simple example: > > iterable = [iter([])] > list(next(x) for x in iterable) > => returns [] > > But: > > [next(x) for x in iterable] > => raises StopIteration > > > Has anyone come across this difference in the wild? Was it a problem? Do you > rely on that difference, or is it a nuisance? Has it caused difficulty in > debugging code? > > If you had to keep one behaviour, which would you keep? Wow, that's really esoteric. I can't imagine this happening in real-life code (but I'm sure somebody will come up with an example :-)) My inclination is that a list comprehension should stop if StopIteration is raised by the comprehension body. I can't come up with a good argument to support that, other than it seems like the right thing to do. -- https://mail.python.org/mailman/listinfo/python-list
