[Python-Dev] Switch statement
jimjjewett at gmail.com
Fri Jun 23 23:20:05 CEST 2006
On 6/23/06, Guido van Rossum <guido at python.org> wrote:
> Here are a few examples showing my objections against first-use.
[Problem with nested scopes; today this usually shows up as (invalid)
bug reports about lambda, in which failure to bind a "default"
variable "to itself" causes it to take on the value at the end of the
loop, instead of the value of the index when defined.]
[Problem with using a parameter as a case selector -- at least these
aren't available at definition time.]
> With the def-time rule, you'd have to work a lot harder to construct
> an example that works differently than the casual reader would expect.
Anything which use the same names in the local scope, particularly if
those names are themselves marked final (or static).
a=4 # This gets ignored?
final b=5 # But what about this? It is local, but a
constant known in advance
case in (a, b, c): ...
final c=6 # Also a constant, but textually after the case keyword.
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