Steven D'Aprano wrote:
On Sun, 26 Dec 2010 09:15:32 -0800, Ethan Furman wrote:
Steven D'Aprano wrote:
Right. But I have thought of a clever trick to get the result KJ was
asking for, with the minimum of boilerplate code. Instead of this:
def _pre_spam(args):
if condition(args):
raise SomeException("message")
if another_condition(args):
raise AnotherException("message")
if third_condition(args):
raise ThirdException("message")
def spam(args):
_pre_spam(args)
do_useful_work()
you can return the exceptions instead of raising them (exceptions are
just objects, like everything else!), and then add one small piece of
boilerplate to the spam() function:
def _pre_spam(args):
if condition(args):
return SomeException("message")
if another_condition(args):
return AnotherException("message")
if third_condition(args):
return ThirdException("message")
def spam(args):
exc = _pre_spam(args)
if exc: raise exc
do_useful_work()
-1
You failed to mention that cleverness is not a prime requisite of the
python programmer -- in fact, it's usually frowned upon. The big
problem with the above code is you are back to passing errors in-band,
pretty much completely defeating the point of have an out-of-band
channel.
How is that any worse than making _pre_spam() a validation function that
returns a bool?
def spam(args):
flag = _pre_spam(args)
if flag: raise SomeException()
do_useful_work()
Also -1.
Is that also frowned upon for being too clever?
Frowned upon for being out-of-band, and not as much fun as being clever.
;) I'm pretty sure you've expressed similar sentiments in the past
(although my memory could be failing me).
More to the point, the OP had code that said:
args, kwargs = __pre_spam(*args, **kwargs)
and __pre_spam was either passing back verified (and possibly modified)
parameters, or raising an exception.
~Ethan~
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