On Sat, Jun 13, 2009 at 2:11 PM, kj<no.em...@please.post> wrote: > > > Switching from Perl here, and having a hard time letting go... > > Suppose I have an "array" foo, and that I'm interested in the 4th, 8th, > second, and last element in that array. In Perl I could write: > > my @wanted = @foo[3, 7, 1, -1]; > > I was a bit surprised when I got this in Python: > >>>> wanted = foo[3, 7, 1, -1] > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: list indices must be integers > > Granted, Perl's syntax is often obscure and hard-to-read, but in > this particular case I find it quite transparent and unproblematic, > and the fictional "pythonized" form above even more so. > > The best I've been able to come up with in Python are the somewhat > Perl-like-in-its-obscurity: > >>>> wanted = map(foo.__getitem__, (3, 7, 1, -1)) > > or the clearer but unaccountably sesquipedalian > >>>> wanted = [foo[i] for i in 3, 7, 1, -1] >>>> wanted = [foo[3], foo[7], foo[7], foo[-1]] > > Are these the most idiomatically pythonic forms? Or am I missing > something better? >
There is only so much room in the syntax for common cases before you end up with ... perl (no offense intended, I'm a perl monk[1]). The Python grammar isn't as context sensitive or irregular as the perl grammar so mylist[1,2,3] so the "1,2,3" tuple is always interpreted as a tuple and the square brackets always expect an int or a slice. Not including special cases everywhere means there isn't a short way to handle special cases but it also means human readers have to remember fewer special cases. Perl and Python make different tradeoffs in that respect. -Jack [1] http://www.perlmonks.org/?node_id=111952 -- http://mail.python.org/mailman/listinfo/python-list
