PEP 276 Simple Iterator for ints

Tim Hochberg tim.hochberg at ieee.org
Wed Nov 14 05:28:09 CET 2001


"William Tanksley" wrote :
> James_Althoff at i2.com wrote:
[SNIP]
> >    - It would be better to reuse the ellipsis literal syntax (...)
> >      Response: Shares disadvantages of other proposals that require
> >      changes to the syntax.  Needs more design to determine how it
> >      would handle the general case of start,stop,step,
> >      open/closed/half-closed intervals, etc.  Needs a PEP.
>
> The last sentance is the only one that matters here.  However, I'm
> curious: what do you mean "reuse"?  I've never seen an "ellipsis literal"
> in Python.  Reading through the Python documentation, I see an ellipsis
> notation for extended slicing, but I'm in the dark as to what it means.
> (I can guess, but I'd rather see it in print.)  I've never seen it in
> Python code, and the documentation doesn't seem to mention it.

As far as I know the ellipsis syntax is only currently used in NumPy. It's a
builtin, though -- you can see it just by typing Ellipsis at the prompt. You
could use it today if you wanted:

someObject[a, b, ..., c]

gets translated to:

someObject.__getitem__((a, b, Ellipsis, c))

So you can use it in your own class if you want. In particular, one could
make

int[1,3,...,53] act like range(1,53,2) if one wanted.

-tim








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