Recent changes to bugs

Comparisons

Anonymous — Thu, 29 Jan 2004 21:44:34 -0000

x = FixedPoint("1.1")
print x == None

produces an exception, rather than returning False.

According to the docs:

"The operators <, >, ==, >=, <=, and != compare
the values of two objects. The objects need not
have the same type. If both are numbers, they are
converted to a common type. Otherwise, objects of
different types always compare unequal, and are
ordered consistently but arbitrarily."

For FixedPoint this should perhaps read "If both or
numbers or strings that can be parsed by FixedPoint.
..." -- otherwise it seems more logical that the
above snippet should return False, not raise an
exception (integers work that way).

FixedPoint objects cannot be pickled

Duane Voth — Wed, 23 Jul 2003 22:22:20 -0000

Python 2.2.1 (#1, Sep 9 2002, 09:26:21)
[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux-i386
Type "help", "copyright", "credits" or "license" for
more information.
>>> from fixedpoint import FixedPoint
>>> x = FixedPoint("1.234")
>>> print x
1.23
>>> import pickle
>>> f = open("foo", 'w')
>>> pickle.dump(f, x)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.2/pickle.py", line 973, in dump
Pickler(file, bin).dump(object)
File "/usr/lib/python2.2/pickle.py", line 110, in
__init__
self.write = file.write
AttributeError: 'FixedPoint' object has no attribute
'write'
>>> import cPickle
>>> cPickle.dump(f, x)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: argument must have 'write' attribute
>>>

Wrong internal version number

GaryD — Wed, 26 Feb 2003 05:25:25 -0000

I just downloaded FixedPoint v0.1.2 (after an amusing
half hour reading the mail archives), and discovered
that the internal version number is actually set to:
__version__ = 0, 1, 0

This might be something you care about, or it might not :-)

Problem subclassing

Anonymous — Tue, 15 Oct 2002 11:27:43 -0000

The following fails when using the subclass
(recursion
problem), but works using the base class.

It worked with
the last "pre-Sourceforge" version of FixedPoint, so
I
presume this might be a bug in the latest version -- I just can't
for
the life of me see what could cause this!

(Posted
here at Doug Fort's suggestion -- I initially assumed this was
something to do with the subclassing).

Paul
Mothersdill

==================================================
from
fixedpoint import FixedPoint

class FP(FixedPoint)
:
"""Subclass of FixedPoint"""
def __init__(self, value,
precision):
FixedPoint.__init__(self, value,
precision)

def _test():
_y = 378
_x = FP(793.1 ,
6)
#_x = FixedPoint(793.1 , 6)
_z = _y/_x
print
type(_y) , ' : ' , _y
print type(_x) , ' : ' , _x
print type(_z) , ' : ' , _z

if __name__ == '__main__':
_test()

rounding not appropriate

Anonymous — Tue, 24 Sep 2002 21:09:26 -0000

The current implementation uses 'round-half-even':
>>> FixedPoint(3, 0) / FixedPoint(2, 0)
FixedPoint('2.', 0)
>>> FixedPoint(5, 0) / FixedPoint(2, 0)
FixedPoint('2.', 0)

The starting point of the discussion on
comp.lang.python preceding this project was Python's
lack of a numerical type suitable for business
applications, and I can't imagine a business app using
'round-half-even'. According to my experience, the
"common business practice" uses 'round-half-up', so I
would recommend this, at least as default.

comparision to None raises exeption

Anonymous — Tue, 24 Sep 2002 20:51:21 -0000

This was first reported on comp.lang.python by Mark
McEahern:
<mark@mceahern.com> wrote:
> In the FixedPoint module found here:
>ftp://ftp.python.org/pub/python/contrib-09-Dec-1999/DataStructures/FixedPoint.py.Z
> there seems to be a bug comparing to None like this:
>
> if f == None:
>
> Demo:
>
> $ python
> Python 2.2 (#1, Dec 31 2001, 15:21:18)
> [GCC 2.95.3-5 (cygwin special)] on cygwin
> Type "help", "copyright", "credits" or "license"
for more information.
> >>> import FixedPoint
> >>> f = FixedPoint.FixedPoint(1.0)
> >>> if f == None:
> ... print "that's not true!"
> ...
> Traceback (most recent call last):
> File "<stdin>", line 1, in ?
> File "FixedPoint.py", line 272, in __cmp__
> xn, yn, p = _norm(self, other)
> File "FixedPoint.py", line 415, in _norm
> y = FixedPoint(y, x.p)
> File "FixedPoint.py", line 216, in __init__
> raise TypeError("can't convert to FixedPoint:
" + `value`)
> TypeError: can't convert to FixedPoint: None

Although it's always good practice to use
if f is None:
instead of
if f == None:
FixedPoint should not raise an exection, because the
built-in types don't do so:
Python 2.2.1 (#34, Apr 9 2002, 19:34:33) [MSC 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for
more information.
>>> 1 == None
0
>>>

A "fix" could look like:

def __cmp__(self, other):
# inserted:
if other is None:
return 1
#---
xn, yn, p = _norm(self, other)
return cmp(xn, yn)