[IPython-User] Prefilter problem

Alan Bromborsky abrombo@verizon....
Sun Jan 22 11:04:05 CST 2012

I found the following example of  an ipython prefilter -

# -*- coding: utf-8 -*-
"""Modified input prompt for entering quantities with units.

Modify the behavior of the interactive interpreter to allow direct input of
quantities with units without having to make a function call.

Now the following forms are accepted:

x = 4 m
y = -.45e3 m/s
g = 9.8 m/s**2
a = 2.3 m/s^2   # ^ -> ** automatically

All other input is processed normally.

- Fernando Perez <Fernando.Perez@berkeley.edu>
#       Copyright (C) 2008-2009 The IPython Development Team
#       Copyright (C) 2001-2007 Fernando Perez <fperez@colorado.edu>
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.

# This file is an example of how to modify IPython's line-processing 
# without touching the internal code. We'll define an alternate 
# stage which allows a special form of input (which is invalid Python 
# for certain quantities, rewrites a line of proper Python in those 
cases, and
# then passes it off to IPython's normal processor for further work.

# With this kind of customization, IPython can be adapted for many
# special-purpose scenarios providing alternate input syntaxes.

# This file can be imported like a regular module.

# IPython has a prefilter() function that analyzes each input line. We 
# it here to first pre-process certain forms of input

# The prototype of any alternate prefilter must be like this one (the name
# doesn't matter):
# - line is a string containing the user input line.
# - continuation is a parameter which tells us if we are processing a 
first line of
#   user input or the second or higher of a multi-line statement.

def prefilter_PQ(self,line,continuation):
     """Alternate prefilter for input of PhysicalQuantityInteractive 

     This assumes that the function PhysicalQuantityInteractive() has been

     from re import match
     from IPython.iplib import InteractiveShell

     # This regexp is what does the real work
     unit_split = 

     # If special input was ecnountered, process it:
     if unit_split:
         var,val,units = unit_split.groups()
         if var and val and units:
             units = units.replace('^','**')
             # Now a valid line needs to be constructed for IPython to 
             line = var +" = PhysicalQuantityInteractive(" + val + ", '" + \
                    units + "')"
             #print 'New line:',line   # dbg

     # In the end, always call the default IPython _prefilter() 
function.  Note
     # that self must be passed explicitly, b/c we're calling the 
unbound class
     # method (since this method will overwrite the instance prefilter())
     return InteractiveShell._prefilter(self,line,continuation)

# Rebind this to be the new IPython prefilter:
from IPython.iplib import InteractiveShell
InteractiveShell.prefilter = prefilter_PQ

# Clean up the namespace.
del InteractiveShell,prefilter_PQ

# Just a heads up at the console
print '*** Simplified input for physical quantities enabled.'

and included the code in ipython_config.py.  However in version 0.12  
IPython.iplib no longer exists and if I use 
IPython.core.interactiveshell instead 
InteractiveShell._prefilter(self,line,continuation) does not exist.  
What do I need to do to update this code?

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