[Python-Dev] Negative times behaviour in itertools.repeat for Python maintenance releases (2.7, 3.3 and maybe 3.4)

[Larry Hastings]

On 01/27/2014 06:26 PM, Vajrasky Kok wrote:
> So I believe the doc fix is required then.


I propose the docstring should describe only supported behavior, and the 
docs in the manual should mention the unsupported behavior. However, I'm 
interested in Raymond's take, as he's the original author of 
itertools.repeat.


If I were writing it, it might well come out like this:


docstring:

    repeat(object [,times]) -> iterator

    Return an iterator which yields the object for the specified number
    of times.  If times is unspecified, yields the object forever.  If
    times is negative, behave as if times is 0.


documentation:

    repeat(object [,times]) -> iterator

    Return an iterator which yields the object for the specified number
    of times.  If times is unspecified, yields the object forever.  If
    times is negative, behave as if times is 0.

    Equivalent to:

    def repeat(object, times=None):
         # repeat(10, 3) --> 10 10 10
         if times is None:
             while True:
                 yield object
         else:
             for i in range(times):
                 yield object

    A common use for repeat is to supply a stream of constant values to
    map or zip:

     >>>
     >>> list(map(pow, range(10), repeat(2)))
    [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

    .. note:  if "times" is specified using a keyword argument, and
    provided with a negative value, repeat yields the object forever.
    This is a bug, its use is unsupported, and this behavior may be
    removed in a future version of Python.



//arry/
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