[ python-Bugs-1119418 ] xrange() builtin accepts keyword arg silently

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Bugs item #1119418, was opened at 2005-02-09 11:57
Message generated for change (Comment added) made by tjreedy
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Category: Python Library
Group: None
Status: Open
Resolution: None
Priority: 6
Submitted By: Martin Blais (blais)
Assigned to: Nobody/Anonymous (nobody)
Summary: xrange() builtin accepts keyword arg silently

Initial Comment:
Calling ``xrange(10, 100, step=10)`` results in a
xrange(10, 100) iterator silently.  In contrast,
``range(10, 100, step=10)`` raises an exception.  See
test program below.

Two possible fixes:
1. fix xrange() so that it returns a xrange(10, 100,
10) iterator
2. make sure that xrange() raises an exception too.



#!/usr/bin/env python

def foo( min_, max_, step=1 ):
    print min_, max_, step

print '===================='
foo(10, 100, 10)
foo(10, 100, step=10)

print '===================='
print xrange(10, 100, 10)
print xrange(10, 100, step=10)

print '===================='
print range(10, 100, 10)
print range(10, 100, step=10)





elbow:/usr/.../lib/python2.4$ /tmp/a.py
====================
10 100 10
10 100 10
====================
xrange(10, 100, 10)
xrange(10, 100)
====================
[10, 20, 30, 40, 50, 60, 70, 80, 90]
Traceback (most recent call last):
  File "/tmp/a.py", line 16, in ?
    print range(10, 100, step=10)
TypeError: range() takes no keyword arguments

> /tmp/a.py(16)?()
-> print range(10, 100, step=10)
(Pdb) 
elbow:/usr/.../lib/python2.4$ 


----------------------------------------------------------------------

Comment By: Terry J. Reedy (tjreedy)
Date: 2005-02-16 17:21

Message:
Logged In: YES 
user_id=593130

Functions coded in C generally do not take keyword 
arguments.  (Special coding is required to achieve 
otherwise.)  In 2.2, range and xrange both followed this rule:

>>> xrange(1,20,step=2)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: xrange() takes no keyword arguments

>>> range(1,20,step=2)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: range() takes no keyword arguments

So, removal of the error message by 2.4 seem to be a bug.

Surprise:
>>> str(object=1)
'1'
>>> str(i=2)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: 'i' is an invalid keyword argument for this function

There is nothing in the doc(Lib Ref) or doc string of str vs. 
range and xrange that would lead me to expect this.

I looked around CVS a bit to see if the past or possible future 
change was something simple, but I could not find source of 
error message in bltinmodule.c, ceval.c, getargs.c,  
rangeobject.c, or typeobject.c, so I will leave this to 
someone else.

----------------------------------------------------------------------

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