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# -*- coding: utf-8 -*-
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"""Modified input prompt for entering quantities with units.
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Modify the behavior of the interactive interpreter to allow direct input of
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quantities with units without having to make a function call.
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Now the following forms are accepted:
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x = 4 m
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y = -.45e3 m/s
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g = 9.8 m/s**2
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a = 2.3 m/s^2 # ^ -> ** automatically
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All other input is processed normally.
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Authors
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-------
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- Fernando Perez <Fernando.Perez@berkeley.edu>
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"""
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#*****************************************************************************
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# Copyright (C) 2008-2011 The IPython Development Team
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# Copyright (C) 2001-2007 Fernando Perez <fperez@colorado.edu>
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#*****************************************************************************
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# This file is an example of how to modify IPython's line-processing behavior
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# without touching the internal code. We'll define an alternate pre-processing
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# stage which allows a special form of input (which is invalid Python syntax)
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# for certain quantities, rewrites a line of proper Python in those cases, and
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# then passes it off to IPython's normal processor for further work.
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# With this kind of customization, IPython can be adapted for many
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# special-purpose scenarios providing alternate input syntaxes.
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# This file can be imported like a regular module.
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# IPython has a prefilter() function that analyzes each input line. We redefine
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# it here to first pre-process certain forms of input
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# The prototype of any alternate prefilter must be like this one (the name
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# doesn't matter):
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# - line is a string containing the user input line.
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# - continuation is a parameter which tells us if we are processing a first line of
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# user input or the second or higher of a multi-line statement.
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def prefilter_PQ(self,line,continuation):
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"""Alternate prefilter for input of PhysicalQuantityInteractive objects.
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This assumes that the function PhysicalQuantityInteractive() has been
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imported."""
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from re import match
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from IPython.core.iplib import InteractiveShell
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# This regexp is what does the real work
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unit_split = match(r'\s*(\w+)\s*=\s*(-?\d*\.?\d*[eE]?-?\d*)\s+([a-zA-Z].*)',
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line)
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# If special input was ecnountered, process it:
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if unit_split:
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var,val,units = unit_split.groups()
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if var and val and units:
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units = units.replace('^','**')
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# Now a valid line needs to be constructed for IPython to process:
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line = var +" = PhysicalQuantityInteractive(" + val + ", '" + \
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units + "')"
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#print 'New line:',line # dbg
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# In the end, always call the default IPython _prefilter() function. Note
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# that self must be passed explicitly, b/c we're calling the unbound class
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# method (since this method will overwrite the instance prefilter())
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return InteractiveShell._prefilter(self,line,continuation)
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# Rebind this to be the new IPython prefilter:
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from IPython.core.iplib import InteractiveShell
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InteractiveShell.prefilter = prefilter_PQ
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# Clean up the namespace.
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del InteractiveShell,prefilter_PQ
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# Just a heads up at the console
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print '*** Simplified input for physical quantities enabled.'
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