What value should be passed to make a function use the default argument value?

[Antoon Pardon]

On 2006-10-04, Paul Rubin <http> wrote:
> Antoon Pardon <apardon at forel.vub.ac.be> writes:
>> Now in this case you could start by assigning arg the value 1 and
>> eliminate the if test. However that only works if you know the
>> default value for the argument. What he seems to be asking for
>> is if there is an object, (let as call it Default), that would
>> make code like:
>> 
>>   def f(var=1):
>> 
>> Equivallent to:
>> 
>>   def f(var=Default)
>>     if var is Default)
>>       var = 1
>
> Oh, I see.  Yes, the OP should just use a distinct default value
> instead of 1.  I usually do this with
>
>    sentinel = object()
>
>    def f(var=sentinel):
>      if var is sentinel:
>        # f was called without an arg 

But that can only work if you are the author of f. Take the
following code:

  def myrepeat(obj, times = xxx):
    return itertools.repeat(obj, times)

What value do I have to substitue for xxx, so that myrepeat
will have the exact same function as itertools.repeat?

-- 
Antoon Pardon