Am I the only one who would love these extentions? - Python 3.0 proposals (long)

Andrew Dalke adalke at mindspring.com
Tue Nov 11 10:01:09 CET 2003


Just to highlight a new suggestion I made that I hadn't seen before,
use eillipsis ("...") at the end of a list assignment to mean "ignore the
rest of
the RHS."  This would allow a style of enum definition like

 class Keywords:
   AND, ASSERT, BREAK, CLASS, CONTINUE, DEF,  \
     DEL, ELIF, YIELD, ...  = itertools.count()

 class consts:
   A, B, C, ... = itertools.count()
   D, E, F, G, H, ... = itertools.count(10)

This could also be used in

calendar.py has
    year, month, day, hour, minute, second = tuple[:6]
which would become
    year, month, day, hour, minute, second, ... = tuple

and of course for
(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY) = range(7)
in that same file.

HOWEVER, those are effectively the only two places in the top-level
Python lib which would use this construct correctly.  There are places
where it can be used incorrectly, because I think changing
 OK, BOOM, FAIL = range(3)
into
 OK, BOOM, FAIL, ... = itertools.count()
is overkill -- there should be at least 5 elements before this ... is
useful.

and I think changing
  FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT = 1, 2, 4, 8, 16
into
  FTEXT, FHCRC, FEXTRA, FNAME, FCOMMENT, ... = x*x for x in
itertools.count(1)
is just plain stupid.

Therefore I withdraw this proposal, leaving it for contemplation and
posterity's.

Plus, if accepted then should the following be allowed?

  ..., x, y, z = itertools.count(100)  # get the last three elements
  a, b, c, ..., x, y, z = itertools.count(100)  # get the first three and
last three elements
?

                     Andrew
                     dalke at dalkescientific.com








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