Steve Holden a écrit :
(snip)
What's the exact reason for requiring that a creator argument be of a
specific type? So operations on the instances don't go wrong? Well, why
not just admit that we don't have control over everything, and just *let
things go wrong* when the wrong type is passed?
validation isn't only about types, but that's not the point...
What will then happen? Why, an exception will be raised!
Not necessarily.
def nocheck(stuffs):
"'stuffs' is supposed to be a sequence of strings"
for s in stuffs:
do_something_with(s)
# correct call
good_stuffs = ("role1", "role2", "role3")
nocheck(good_stuffs)
# incorrect call, but the error passes silently
bad_stuffs = "role1"
nocheck(bad_stuffs)
If nocheck happens to be in the core of a huge lib or framework and
stuffs defined somwhere in a huge client app's code you didn't even
wrote, then you might spend hours tracing the bug - been here, done
that, bought the tshirt :(
IOW : while I agree that not doing anything and letting exceptions
propagate is quite often the best thing to do, there are times where
validation makes sense - specially when passing in a wrong value might
NOT raise an exception - just produce unexpected results.
My 2 cents...
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