[Visualpython-users] New Windows VPython

Bruce Sherwood bas at andrew.cmu.edu
Mon Dec 24 19:25:26 EST 2001

You've jumped the gun, but your input is useful nevertheless.

The new Windows version of VPyhon available at vpython.org does NOT 
automatically invoke the new division operators. What it does is PERMIT but 
not require users of VPython to put "from __future__ import division" in 
their programs and have things work correctly, even if they use explicit 
Numeric arrays (as for example is the case in some VPython demo programs). 
So there still is no "VPython fork".

It is true however that I have been thinking quite seriously of making just 
such a version of VPython, possibly only a local version just for our 
physics students. In the absence of "true division" they make "mistakes" 
that are very hard to find and fix. If we do make such a version, we'll 
offer it to others along with a version that doesn't invoke this 
automatically. Alternatively, we'll just teach our students to insert the 
import __future__ statement to avoid the problems they have been 
encountering. This problem stands out in high relief for us because it is 
very nearly the only significant problem they have with Python. (For 
example, our students don't have any problems whatsoever with case 
sensitivity, the other problem that was reported for some novice programmer 

I hope this clarifies for you the VPython situation. What I fixed makes it 
possible to use true division with Numeric, not force you to do so.

This said, I should also however point out that while the serious 
difficulties students had with classic division in both the Alice and 
VPython projects got Guido and others thinking about the issue, it is my 
understanding that these projects were NOT ultimately the basis for 
implementing a path toward a different approach to division. Rather, Guido 
and colleagues came to a new vision of the status of numeric values in 
Python, and a way to unify different kinds of integer in such a way that it 
shouldn't matter whether a quantity happens to be an integer or a float.

Bruce Sherwood

--On Monday, December 24, 2001 18:17 -0500 Arthur Siegel 
<ajs at ix.netcom.com> wrote:

> ----- Original Message -----
> From: "Bruce Sherwood" <bas at andrew.cmu.edu>
> To: <visualpython-users at lists.sourceforge.net>
> Sent: Monday, December 24, 2001 5:11 PM
> Subject: [Visualpython-users] New Windows VPython
>> At vpython.org is a new VPython for Windows that patches gaps in the
>> Numeric module used in some VPython demo programs (and automatically
>> imported by Visual). The update makes division of Numeric arrays work
>> properly in the presence of "from __future__ import division". The
>> patches to Numeric have been submitted to the keepers of the Numeric
>> project.
>> Bruce Sherwood
> Bruce -
> I am in the strange position of being a vocal advocate of
> VPython, and a vocal critic of the decision on the division
> operator, at least to the extent it was made to accommodate
> VPython and similar projects.  And precisely, as I stated at
> the time of the wars,  because Numeric is the dog and VPython
> the tail when it comes to handling numerics, and as I stated at
> the time, the change is inconsistent, or at least inelegantly consistent,
> with Numeric typing, and, as I stated at the time of the wars, the
> change could be expected to lead to a deeper level of confusion
> and more insidious bugs if folks try to use VPython without being
> aware of the Numeric typing and coercian rules - to which the
> divison change is, almost by intent, an open invitation.
> And I inflamed an already difficult relationship with Guido and others
> in the community as a result of my position, or at least its vehemence,
> and my method of communciating my position.
> There was no VPython fork of Python as Guido had apparently thought,
> but as of today, apparently there *is* a VPython fork of Numeric.
> That a project of mine, that is dear to me, is dependent on VPython and
>  so -
> at least temporarily, a fork of Numeric, is - I think you might be able
> to understand - quite upsetting.
> Art

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