Re: [Visualpython-users] Problems with exception handling in vpython on Linux

[Guenter S. <Gue...@ph...>]

See below.

Robert Xiao wrote:
> 
> 
> ---------- Forwarded message ----------
> From: *Robert Xiao* <nne...@gm... <mailto:nne...@gm...>>
> Date: 2009/8/31
> Subject: Re: [Visualpython-users] Problems with exception handling in 
> vpython on Linux
> To: Guenter Schneider <Gue...@ph... 
> <mailto:Gue...@ph...>>
> 
> 
> 2009/8/31 Guenter Schneider <Gue...@ph... 
> <mailto:Gue...@ph...>>
> 
>     I ran into a number of problems with vpython on Linux which appear to be
>     all related. The problems do not happen in Windows. My system is ubuntu
>     9.04, vpython 5.12 compiled from source (5.11 gives identical results).
> 
> 
> What version of the Boost libraries are you using?
boost 1.35 (libboost1.35-dev)
>  
> 
>     Thee common feature I see on Linux is, whenever vpython raises an
>     exception, python seg. faults.
> 
>     Example 1:
> 
>     In [1]: from visual import *
> 
>     In [2]: a = vector(1,2,3)
> 
>     In [3]: for i in a:
>        ...:     print i
>        ...:
>        ...:
>     1.0
>     2.0
>     3.0
>     Segmentation fault
>     ~ $
> 
>     but the following works:
> 
>     Example 2:
> 
>     In [1]: from visual import *
> 
>     In [2]: a = vector(1,2,3)
> 
>     In [3]: for i in a:
>        ...:     print i
>        ...:     if i>2:
>        ...:         break
>        ...:
>        ...:
>     1.0
>     2.0
>     3.0
> 
>     This seems to point to the raising a StopIteration exception as the
>     problem point.
> 
> 
>     Example 3:
>     In [1]: from visual import *
> 
>     In [2]: a = [1,2,3]
> 
>     In [3]: mag2(a)
>     Out[3]: 14.0
> 
>     In [4]: a = [1,2,'x']
> 
>     In [5]: mag2(a)
>     Segmentation fault
>     ~ $ 
> 
> 
>     It should have raised a TypeError as in this case
> 
> It's actually Boost.Python.ArgumentError, since [1,2,'x'] can't be 
> coerced to a vector, so it is passed in as a list.

I was guessing and did not try everything on Windows.

> 
>  >>> visual.mag2([1,2,'x'])
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> Boost.Python.ArgumentError: Python argument types in
>     visual.cvisual.mag2(list)
> did not match C++ signature:
>     mag2(class cvisual::vector)
>     mag2(class boost::python::numeric::array)
>  
> 
>     Finally this fails as well:
> 
>     Example 5:
>     In [1]: from visual import *
> 
>     In [2]: quit()
>     Do you really want to exit ([y]/n)?
>     Segmentation fault
>     ~ $
> 
> quit() is a Python built-in, and it isn't overridden by Visual. Does 
> quit() work if you don't import visual?

Yes.

> 
> Can you try these tests:
> vector(1,2,3)[4] # throws std::out_of_range
> vector('x')
> faces(pos=[1])
> faces(normal=[])
> 
> These all directly throw exceptions.
> 
All end in seg. faults on my system.

In [1]: from visual import *

In [2]: faces(normal=[])
Segmentation fault

I appreciate your help.

Guenter

> 
> 
> 2009/8/31 Bruce Sherwood <Bru...@nc... 
> <mailto:Bru...@nc...>>
> 
>     Moreover, your Example 1 is exceptionally strange, as it should not
>     give an
> 
>     error of any kind (nor does it give an error for me). Is it possible
>     that
>     there's a typo in your reporting of Example 1?
> 
> 
> StopIteration is raised by an iterator when it has no more objects to 
> iterate over. It is not an error, but it can be raised by an iterator.
> 
> Robert
> 
> 
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-- 
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Guenter Schneider

Email:  Gue...@ph...
Phone:  541 737 1706
Fax:    541 737 1683

Oregon State University
Department of Physics
301 Weniger Hall
Corvallis, OR 97331-6507, USA
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