for loop without variable

[Ben Finney]

erik gartz <eegunnar at yahoo.com> writes:

> The loop performs some actions with web services. The particular
> iteration I'm on isn't important to me. It is only important that I
> attempt the web services that number of times. If I succeed I
> obviously break out of the loop and the containing function (the
> function which has the loop in it) returns True. If all attempts
> fail the containing loop returns False.

When you have iteration requirements that don't seem to fit the
built-in types (lists, dicts, generators etc.), turn to 'itertools'
<URL:http://www.python.org/doc/lib/module-itertools> in the standard
library.

    >>> from itertools import repeat

    >>> def foo():
    ...     import random
    ...     print "Trying ..."
    ...     success = random.choice([True, False])
    ...     return success
    ...
    >>> max_attempts = 10
    >>> for foo_attempt in repeat(foo, max_attempts):
    ...     if foo_attempt():
    ...         break
    ... 
    Trying ...
    Trying ...
    Trying ...
    Trying ...
    Trying ...
    Trying ...
    >>> 

Note that this is possibly more readable than 'for foo_attempt in
[foo] * max_attempts", and is more efficient for large values of
'max_attempts' because 'repeat' returns an iterator instead of
actually allocating the whole sequence.

> I guess based on the replies of everyone my best bet is to leave the
> code the way it is and suck up the warning from pylint.

I think your intent -- "repeat this operation N times" -- is better
expressed by the above code, than by keeping count of something you
don't actually care about.

> I don't want to turn the warning off because catching unused
> variables in the general is useful to me.

Agreed.

-- 
 \             "Dyslexia means never having to say that you're ysror." |
  `\                                                        —anonymous |
_o__)                                                                  |
Ben Finney