Clarity vs. code reuse/generality

[kj]

In <7xk52p4tgg.fsf at ruckus.brouhaha.com> Paul Rubin <http://phr.cx@NOSPAM.invalid> writes:

>kj <no.email at please.post> writes:
>>     sense = cmp(func(hi), func(lo))
>>     if sense == 0:
>>         return None
>>     target_plus = sense * target + epsilon
>>     target_minus = sense * target - epsilon
>>     ...

>The code looks confusing to me and in some sense incorrect.  Suppose
>func(hi)==func(lo)==target.

In hindsight, I too think that it is incorrect, but for a different
reason.  I've rewritten it like this:

    sense = cmp(func(hi), func(lo))
    assert sense != 0, "func is not strictly monotonic in [lo, hi]"

I regard the very special case of func(hi)==func(lo)==target as
pathological (analogous to the fact that a stopped watch is "exactly
right" twice a day), and not one I care to support.

Thanks for your feedback!

kj