Scoped change of a global variable

[Luigi Ballabio]

Corrado,

At 11:53 AM 1/2/02 +0100, Corrado Gioannini wrote:
>On Wed, Jan 02, 2002 at 11:29:45AM +0000, Luigi Ballabio wrote:
>[...snip...]
>
>You could define a class like:
>
>precision = 2
>class Add:
>     def __init__(self):
>         self.precision = precision
>     def add(self, x, y):
>         ...
>     def setPrecision(self, n):
>         self.precision = n
>     def restorePrecision(self):
>         self.precision = precision
>
>and then simply:
>
>a = Add()
>a.add(1.0, 0.3456)
>a.setPrecision(3)
>a.add(1.0, 0.3456)
>a.restorePrecision()

Well, the logic is only half-encapsulated here---you still have to call 
restorePrecision() explicitly.

>This if you really don't want to use parameters...
>
>precision = 2
>def add(x, y, z=precision):

Well, add(x,y) was a simple way to write an example. My real purpose would 
be the __add__ method for a class of a numeric kind, which can only take 
the two operands as parameters. The corresponding Ruby example would be:

withPrecision(1) {
     a = b+c
}

Grazie comunque,
                         Luigi