[Python-Dev] Coercion and comparisons

[Ka-Ping Yee]

On Tue, 6 Feb 2001, Ka-Ping Yee wrote:
>     Category        Python operators        E operators
> 
>     identity        is, is not              ==, !=
>     value           ==, !=, <>              x.equals(y), !x.equals(y)
>     magnitude       <, <=, >, >=            <, <=, >, >=, <>, <=>
> 
> Each type of equality has a specific and useful meaning.  Most
> languages, including Python, acknowledge the first two.  But you
> can see how the coercion problem raised above is a consequence
> of the fact that the third category is incomplete.

I didn't state that last sentence very well, and the table's a bit
inaccurate.

Rather, it would be better to say that '==' and '!=' end up having
to do double duty (sometimes for value equality, sometimes for
magnitude equality) -- when really '==' doesn't belong with
ordering operators like '<'.  It's quite a separate concept.


-- ?!ng

"There's no point in being grown up if you can't be childish sometimes."
    -- Dr. Who