Home Original page

[Python-ideas] Python reviewed

Chris Barker - NOAA Federal chris.barker at noaa.gov
Wed Jan 11 11:50:48 EST 2017 
 for range(1,1): means executing once to me.

The indexing/slicing approach was designed for indexing and slicing. Then
it made sense to have range() match. But range() is not part of the for
construction. It is a convenience function for providing an iterable of
integers. And you are welcome to write your own range-like iterable if you
want.

But if you want to look once, you'd use range(1), not range(1,2) anyway.
Clear as day.

And if you use: range(n, n+I), it is very clear that you will loop i times.

s[:n] + s[n:] == s    // doesn't work. I don't think it should work though


Have you ever used a 1-based and closed-end indexing language that
supported slicing? I have (matlab), and these kinds of constructions are
really ugly and prone to error. It's not that you want to be able to divide
a sequence and immediately put it back together, it's that you often want
to do one thing with the first part of a sequence, and another with the
second part, and you don't want them to overlap.

len(s[:n]) == n       // works
len(s[:-n]) == n      // rather independent but would still work if
language is otherwise unchanged.
len(s[n:i]) == i - n  // doesn't work. Does it need to?


It's not that it HAS to - it's that it's much less likely that you will
make off by one errors if it does.

-CHB
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20170111/675eda65/attachment.html>
More information about the Python-ideas mailing list