Guido van Rossum wrote:
> But in most cases the 'constant' is actually an expression involving a
> global, often even a global in another module. (E.g. sre_compile.py)
> The compiler will have a hard time proving that this is really a
> constant, so it won't optimize the code.
unless we come up with a way to make it possible to mark an variable as
a constant.
> The proposed switch semantics (create the table when the containing
> function is defined) get around this by "defining" what it means by
> "constant".
well, given that people find it really confusing that the two X:es in
def func(value=X):
print X
are evaluated at different times, I'm not sure it's a good idea to
introduce more "evaluation scopes".
but sure, I'm sure people doing certification tests would love questions
like:
Q: If a program calls the 'func' function below as 'func()'
and ONE and TWO are both integer objects, what does 'func'
print ?
ONE = 1
TWO = 2
def func(value=ONE):
switch value:
case ONE:
print value, "is", ONE
case TWO:
print value, "is", TWO
a: "1 is 1"
b: "2 is 2"
c: nothing at all
d: either "1 is 1" or nothing at all
e: who knows ?
but I cannot say I find it especially Pythonic, really...
</F>
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