[Tim, objects to abusing assertions]
[Paul Prescod]
> So you prefer
>
> if __debug__ and node.nodeType!=ELEMENT_TYPE:
> raise TypeError
I personally prefer
if node.nodeType != ELEMENT_TYPE:
raise TypeError
if that is in fact a correct test of whatever user-input precondition it is
you're verifying. An assert would be appropriate if it were "impossible"
for the test to fail.
> Unfortunately there's no way to turn that off at "compile time" so you
> always incur the __debug__ lookup cost. That would send us back to two
> versions of the methods.
Actually, there is:
if __debug__:
if node.nodeType != ELEMENT_TYPE:
raise TypeError
Python produces no code for that block under -O (btw, this is the same
mechanism that makes asserts vanish under -O: it's __debug__ that's magic,
not asserts).
As a user, though, I don't expect -O to turn off argument verification!
Same as the Python implementation in these respects: public API functions
*always* check their arguments, while some private API functions check only
in Debug builds (and via the C library's assert() function, as it's a bug in
the implementation if a private API is misused).
do-s-right-thing-ly y'rs - tim
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