Wrapping float

[Sybren Stuvel]

Hi all,

I'm trying to make a float-like class (preferably a subclass of
'float') that wraps around. The background: I'm modeling a
multi-dimensional space, and some of those dimensions are circular.

Here is my code so far:

class WrapFloat(float ):
def __init__(self, value, wrap = None):
float.__init__( self, value)
self.wrap = wrap

The problem is this:

Python 2.4.1 (#2, Mar 30 2005, 21:51:10)
[GCC 3.3.5 (Debian 1:3.3.5-8ubuntu2)] on linux2
Type "help", "copyright" , "credits" or "license" for more information.[color=blue][color=green][color=darkred]
>>> from engine.geometry import WrapFloat
>>> WrapFloat(45)[/color][/color][/color]
45.0[color=blue][color=green][color=darkred]
>>> WrapFloat(45, 3)[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: float() takes at most 1 argument (2 given)

So my question to you is: how can I change my code so I can pass two
values to the WrapFloat constructor?

Thanks in advance,
Sybren
--
The problem with the world is stupidity. Not saying there should be a
capital punishment for stupidity, but why don't we just take the
safety labels off of everything and let the problem solve itself?
Frank Zappa

[Bengt Richter]

Re: Wrapping float

On Sat, 17 Sep 2005 11:12:34 +0200, Sybren Stuvel <sybren@localho st.localdomain> wrote:
[color=blue]
>Hi all,
>
>I'm trying to make a float-like class (preferably a subclass of
>'float') that wraps around. The background: I'm modeling a
>multi-dimensional space, and some of those dimensions are circular.
>
>Here is my code so far:
>
>class WrapFloat(float ):
> def __init__(self, value, wrap = None):
> float.__init__( self, value)
> self.wrap = wrap
>
>The problem is this:
>
>Python 2.4.1 (#2, Mar 30 2005, 21:51:10)
>[GCC 3.3.5 (Debian 1:3.3.5-8ubuntu2)] on linux2
>Type "help", "copyright" , "credits" or "license" for more information.[color=green][color=darkred]
>>>> from engine.geometry import WrapFloat
>>>> WrapFloat(45)[/color][/color]
>45.0[color=green][color=darkred]
>>>> WrapFloat(45, 3)[/color][/color]
>Traceback (most recent call last):
> File "<stdin>", line 1, in ?
>TypeError: float() takes at most 1 argument (2 given)
>
>So my question to you is: how can I change my code so I can pass two
>values to the WrapFloat constructor?
>[/color]
Float is an immutable, so you need to override __new__

Regards,
Bengt Richter

[Robert Kern]

Re: Wrapping float

Sybren Stuvel wrote:[color=blue]
> Hi all,
>
> I'm trying to make a float-like class (preferably a subclass of
> 'float') that wraps around. The background: I'm modeling a
> multi-dimensional space, and some of those dimensions are circular.
>
> Here is my code so far:
>
> class WrapFloat(float ):
> def __init__(self, value, wrap = None):
> float.__init__( self, value)
> self.wrap = wrap
>
> The problem is this:
>
> Python 2.4.1 (#2, Mar 30 2005, 21:51:10)
> [GCC 3.3.5 (Debian 1:3.3.5-8ubuntu2)] on linux2
> Type "help", "copyright" , "credits" or "license" for more information.
>[color=green][color=darkred]
>>>>from engine.geometry import WrapFloat
>>>>WrapFloat(4 5)[/color][/color]
>
> 45.0
>[color=green][color=darkred]
>>>>WrapFloat(4 5, 3)[/color][/color]
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in ?
> TypeError: float() takes at most 1 argument (2 given)
>
> So my question to you is: how can I change my code so I can pass two
> values to the WrapFloat constructor?[/color]

You also have to override __new__ I think. It automatically gets passed
the arguments to __init__. C.f.

http://www.python.org/2.2/descrintro.html#__new__

In [11]: class WrapFloat(float ):
....: def __new__(cls, value, *args, **kwds):
....: return float.__new__(c ls, value)
....: def __init__(self, value, wrap=None):
....: float.__init__( self, value)
....: self.wrap = wrap
....:

In [12]: x = WrapFloat(45, 3)

In [13]: x
Out[13]: 45.0

In [14]: x.wrap
Out[14]: 3

--
Robert Kern
rkern@ucsd.edu

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

[Sybren Stuvel]

Re: Wrapping float

Bengt Richter enlightened us with:[color=blue]
> Float is an immutable, so you need to override __new__[/color]

Thanks, that works!

Sybren
--
The problem with the world is stupidity. Not saying there should be a
capital punishment for stupidity, but why don't we just take the
safety labels off of everything and let the problem solve itself?
Frank Zappa