From: Tim Hammerquist <tim@...>
Date: 2005-09-20T18:31:37+09:00
Subject: Re: ruby idiom for python's for/else while/else

Joe Van Dyk <joevandyk@gmail.com> wrote:
> William Morgan <wmorgan-ruby-talk@masanjin.net> wrote:
> > Excerpts from Gergely Kontra's mail of 19 Sep 2005 (CDT):
> > > >>> for n in range(2, 10):
> > > ...     for x in range(2, n):
> > > ...         if n % x == 0:
> > > ...             print n, 'equals', x, '*', n/x
> > > ...             break
> > > ...     else:
> > > ...         # loop fell through without finding a factor
> > > ...         print n, 'is a prime number'
> > 
> > I don't think there's a direct idiom. I'd write this in Ruby
> > as:
> > 
> > (2...10).each do |n|
> >   fac = (2...n).find { |x| n % x == 0 }
> >   if fac
> >     puts "#{n} equals #{fac} * #{n / fac}"
> >   else
> >     puts "#{n} is a prime number"
> >   end
> > end
> > 
> > This is much clearer IMO.
> 
> Meh, I think the Python version is much clearer.  Each to his
> own, I guess.

I agree that the Python construct is clearer...
*if* you're familiar with the for...else construct.

There are occasions where this construct is very useful,
but it seems to be a slight contradiction to Python's motto of
"There should be one -- and preferably only one -- obvious way
to do it."

Tim Hammerquist