[Python-Dev] accumulator display syntax

Alex Martelli aleaxit at yahoo.com
Fri Oct 17 17:28:23 EDT 2003

On Friday 17 October 2003 10:38 pm, Phillip J. Eby wrote:
> Ironically, with iterator comprehension in place, a list comprehension
> would now look like a list containing an iterator, which I agree might be
> confusing.  Too bad we didn't do iterator comps first, or list(itercomp)
> would be the idiomatic way to make a listcomp.

Yes.  But don't mind me, I'm still sad that we have range and xrange
when iter(a:b) and list(a:b:c) would be SUCH good replacements for
them if slicing-notation was accepted elsewhere than in indexing, or
iter[a:b] and list[a:b:c] if some people didn't so strenuously object to
certain perfectly harmless uses of indexing...;-)

> That's really the only confusing bit I see about itercomps...  that you
> have to be careful where you put your parentheses, in order to make your
> intentions clear in some contexts.  However, that's true for many kinds of
> expressions even now.

Yes.  But since iterator comprehensions are being designed from scratch
I think we can MANDATE parentheses around them, and a 'yield' right
after the open parenthesis for good measure, to ensure they are not
ambiguous to human readers as well as to parsers.


More information about the Python-Dev mailing list