[SciPy-user] Ipython "run"

Howey, David A d.howey at imperial.ac.uk
Wed Aug 24 12:34:21 CDT 2005

thanks for the tips. 'Learning Python' (from O'Rielly - the daddy!) agrees... :-) 'from' and 'reload' don't play together, apparantly. 
I'd better go and modify some code...

-----Original Message-----
From: scipy-user-bounces at scipy.net on behalf of Fernando Perez
Sent: Wed 24/08/2005 17:48
To: SciPy Users List
Subject: Re: [SciPy-user] Ipython "run"
Ryan Krauss wrote:
> I think this will work:
> import foo
> reload(foo)
> from foo import *
> Otherwise you may need to avoid the from foo import * during module 
> development.

I second that last suggestion as well.  I just avoid 'import *' like the 
plague, and rather use (for very heavily used modules) shorthands:

import Numeric as N


The 'import *' is IMHO only justified interactively: not only does it cause 
trouble with name clashes and reload(), but it also makes an often useful 
local optimization tricky:

def func():
   # we're about to do a long loop using some routine from N, so we make
   # it local, which is a faster lookup in python:
   foo = N.foo
   for i in range(BIG):

If you did 'from Numeric import *', you have to do a local change of name, 
since 'foo=foo' is not valid:

In [2]: f()
exceptions.UnboundLocalError                         Traceback (most recent 
call last)


/home/fperez/test/nsp.py in f()
       1 from Numeric import *
       3 def f():
----> 4     array = array
       5     return array([1,2,3])

UnboundLocalError: local variable 'array' referenced before assignment



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