Válas Péter wrote:
> I have a dictionary with the keys 'a' and 'b'. It is not in a class. (I
> know that everything is in a class, but not explicitly.)
> May I use the value of 'a' when defining the value of 'b'? If so, what is
> the syntax?
>>> d = {}
>>> d["a"] = 1
>>> d["b"] = d["a"] + 1
>>> d
{'a': 1, 'b': 2}
If you want the value of "b" updated whenever d["a"] changes, i. e. that the
dict values behave like spreadsheet cells, that is not possible with a
standard python dictionary.
There is a recipe by Raymond Hettinger with a simple implementation of that
behaviour at
http://code.activestate.com/recipes/355045-spreadsheet/
As it uses eval() it is OK for private use, but you shouldn't allow a
potentially malicious user to run it.
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