Q: Python 2.0 preliminary features?

[Guido van Rossum]

Regarding the use of 'global' in combination with nested scopes:
I have always been in favor or *not* providing a way to assign to
variables at the intermediate levels.  That is, you can *use*
variables from intermediate levels, but you can't *set* them.  The
'global' statement will set the variable at the module-global level.

Motivation: I agree that it is useful to reference variables in the
surrounding scope.  But if you start modifying them, you're abusing
the nested scope mechanism to hold mutable state; it's much clearer
to define a class for this purpose.

In particular, I think that allowing

	def f():
		sum = 0
		def accumulate(x):
			global sum
			sum = sum+x
		...code using accumulate()...
		return sum

tends to create obfuscated code.

--Guido van Rossum (home page: http://www.python.org/~guido/)