On Sun, 12 May 2019 at 18:26, David Mertz <me...@gnosis.cx> wrote:
> To be clear in this thread, I don't think I'm really ADVOCATING for a
> multi-level break. My comments are simply noting that I personally fairly
> often encounter the situation where they would be useful. At the same
> time, I worry about Python gaining sometimes-useful features that
> complicate the overall language and bring it closer to Perl's "everyone can
> write in their own style."
>
> So to answer Chris' question... well, i did find something recent, but it
> has a ton of other extraneous stuff. But I've simplified to something that
> isn't that much different from my example from my tablet yesterday, but is
> fairly realistic still.
>
> I have an existing function that looks roughly like this:
>
> def find_needle_in_haystacks():
> found_needle = False
> for haystack in glob.glob('path/to/stuff/*'):
> fh = open(fname)
> header = fh.readline()
> if get_format(header) == 'foo':
> for line in fh:
> status = process_foo(line)
> if status = -1:
> found_needle = True
> break
> elif get_format(header) == 'bar':
> for line in fh:
> status = process_bar(line)
> if status = -1:
> found_needle = True
> break
>
> if found_needle:
> break
>
> If I had a "labelled break" feature, I might rewrite it something like the
> following (picking convenient syntax that I'm not per-se advocating as
> best, even if the concept is adopted):
>
> # Hypothetical future labelled break:
> def find_needle_in_haystacks():
> for haystack in glob.glob('path/to/stuff/*') label HAYSTACKS:
> fh = open(fname)
> header = fh.readline()
> if get_format(header) == 'foo':
> for line in fh:
> if process_foo(line) == -1:
> break HAYSTACKS
> elif get_format(header) == 'bar':
> for line in fh:
> if process_bar(line) == -1:
> break HAYSTACKS
>
>
Nice. Suggestion:
1. replace "label HAYSTACKS" with "as HAYSTACKS", if possible, so no new
keyword is introduced;
2. replace "break HAYSTACKS" with "break from HAYSTACKS"
> In any case, it's often possible to either (a) redefine the inner loop
>>> as some sort of container operation, or (b) redefine the outer
>>> operation as a function, and use "return". So it would be helpful to
>>> have an example that CAN'T be rewritten in one of those ways, to use
>>> as a compelling example.
>>>
>>
> --
> Keeping medicines from the bloodstreams of the sick; food
> from the bellies of the hungry; books from the hands of the
> uneducated; technology from the underdeveloped; and putting
> advocates of freedom in prisons. Intellectual property is
> to the 21st century what the slave trade was to the 16th.
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--
Gustavo J. A. M. Carneiro
Gambit Research
"The universe is always one step beyond logic." -- Frank Herbert
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