do...until wisdom found...

[Dennis Baker]

On Tue, 17 Apr 2001 09:28:15 -0700 Bob Cannard <bob_cannard at mentor.com> wrote:

) Has no one else found that the majority of while-type
) loops actually need some code before the test and some
) after? Doubly so in Python where it seems impossible
) to embed a local side effect in the while condition.
) As a result, most non-for loops degenerate into
) 
)         while 1:
)             set up for this cycle
)             if c: break
)             whatever needs to be done

That's a product of poor design.  I consider it a failure to resort to this sort
of construct.  The only time I resort to it is with Error trapping code where 
you are forced to do something drastic.  For the purpose of debugging code 
readability and reliability you are always better off doing things the "Right" 
way.

-- Dennis

) 
) Instead we keep getting suggestions for another loop
) structure that's comparable in lack of generality to
) "while", instead of taking a good look at how loops
) are formed in practice and generalizing the concept
) accordingly. If new syntax were to be added to the
) language, I'd rather see something like Dale's
) suggestion but removing the constraint that the UNTIL
) (or WHILE) statement has to be at the end - better yet,
) remove the constraint that there can be only one, thus
) making it a synonym for if...break. The existing while
) loop, and the repeat...until loop suggested above, are
) both special cases of the general loop.
) 
) Cheers,
) 
)        Bob.
) -- 
) http://mail.python.org/mailman/listinfo/python-list
)