On Tue, 29 Jul 2008 10:30:43 -0700, Carl Banks wrote:
> On Jul 29, 5:15 am, Heiko Wundram <[EMAIL PROTECTED]> wrote:
>> I can't dig up a simple example from code I wrote quickly, but because
>> of the fact that explicit comparisons always hamper polymorphism
>
> I'm not going to take your word for it. Do you have code that
> demonstrates how "if x" improves polymorphism relative to simple
> explicit tests?
On the rapidly decreasing chance that you're not trolling (looking more
and more unlikely every time you post):
# The recommended way:
if x:
do_something
# Carl's so-called "simple explicit tests" applied to polymorphic code:
try:
# could be a sequence or mapping?
# WARNING: must do this test *before* the number test, otherwise
# "if [] != 0" will return True, leading to the wrong branch being
# taken.
if len(x) != 0:
do_something
except AttributeError:
# not a sequence or mapping, maybe it's a number of some sort
try:
int(x)
except TypeError:
# not convertable to numbers
# FIXME: not really sure what to do here for arbitrary types
# so fall back on converting to a boolean, and hope that works
if bool(x):
do_something
else:
if x != 0:
do_something
But wait... that can be re-written as follows:
if bool(x):
do_something
and that can be re-written without the call to bool:
if x:
do_something
--
Steven
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