Python (1..n) syntax?

问题

I see in the code on this Sage wiki page the following code:

@interact
def _(order=(1..12)):

Is this (1..n) syntax unique to Sage or is it something in Python? Also, what does it do?

回答1:

It's Sage-specific. You can use preparse to see how it is desugared to:

sage: preparse("(1..12)")
'(ellipsis_iter(Integer(1),Ellipsis,Integer(12)))'

See here for documentation of ellipsis_iter, here for information on the preparser.

回答2:

There was a Python PEP to add this notation to Python, but it was rejected. Robert Bradshaw decided to implement it anyways, but for the Sage preparser. He implemented the following:

• (a..b) -- like xrange, so an iterator

• [a..b] -- list, including endpoints

• [a,b,..,c] -- arithmetic progression

回答3:

This is not Python syntax. I would guess that it creates a range from 1 to 12.

回答4:

(1..n) syntax does not exist in Python.

来源：https://stackoverflow.com/questions/3511699/python-1-n-syntax