class SpreadSheet:
_cells = {}
tools = {}
def __setitem__(self, key, formula):
self._cells[key] = formula
def getformula(self, key):
return self._cells[key]
def __getitem__(self, key ):
return eval(self._cells[key], SpreadSheet.tools, self)
>>> from math import sin, pi
>>> SpreadSheet.tools.update(sin=sin, pi=pi, len=len)
>>> ss = SpreadSheet()
>>> ss['a1'] = '5'
>>> ss['a2'] = 'a1*6'
>>> ss['a3'] = 'a2*7'
>>> ss['a3']
210
>>> ss['b1'] = 'sin(pi/4)'
>>> ss['b1']
0.70710678118654746
>>> ss.getformula('b1')
'sin(pi/4)'
