[Python-ideas] Consider making enumerate a sequence if its argument is a sequence

[Steven D'Aprano]

On Wed, Sep 30, 2015 at 12:19:05PM -0700, Andrew Barnert via Python-ideas wrote:
[...]
> > FWIW: I don't think many people use the lazy sequence features
> > of range(), e.g. the slicing or index support. By far most
> > uses are in for-loops.
> 
> I've used range as a sequence (or at least a reusable iterable, a 
> sized object, and a container). I've answered questions from people on 
> StackOverflow who are doing so, and seen the highest-rep Python 
> answerer on SO suggest such uses to other people.
> 
> I don't think I'd ever use the index method (although I did see one SO 
> user who was doing so, to wrap up some arithmetic in a way that avoids 
> a possibly off-by-one error, and wanted to know why it was so slow in 
> 3.1 but worked fine in 3.2...), but there's no reason range should be 
> a defective "not-quite-sequence" instead of a sequence. What would be 
> the point of that?

There's also __contains__.

Personally, I don't like it, but using "n in range(a, b+1)" for testing 
whether integer n falls within a particular range seems to be popular. I 
don't know why they don't just write a <= n <= b, but it seems to be a 
popular idiom for some weird reason.


-- 
Steve