[melbourne-pug] Data type assumptions in Python

[William ML Leslie]

On 5 September 2013 17:07, Javier Candeira <javier at candeira.com> wrote:
> Just one thing. Comparability is transitive, so I don't have to test
> comparability of the new element with all existing elements. I only
> have to check whether it's comparable to the first or root item in the
> structure. So that test is O(1), not O(n).

Well, you hope that comparability is transitive.  In python 2, *order*
wasn't even transitive between the provided numeric types: both
decimal and float would order correctly with respect to int, but not
with respect to each other.

Maybe there's a bit of a flat spot in python teaching in that people
don't know how to use NotImplemented correctly.  On the other hand,
correctly used NotImplemented and __radd__ can't actually solve the
problem of two numeric types implemented in isolation.

-- 
William Leslie

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