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Subject: Re: True == 1 weirdness
Date: Wed, 16 Sep 2015 11:40:44 -0400
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Xref: csiph.com comp.lang.python:96687

On Wed, Sep 16, 2015, at 10:26, Chris Angelico wrote:
> Quite probably never. But are there _any_ comparison operators which
> are unchainable? If not, there's no reason to disallow 'in'

"in" suggests a relationship between objects of different types (X and
"something that can contain X") - all the other comparison operators are
meant to work on objects of the same or similar types.

Why not make isinstance a comparison operator and have "1 instanceof int
instanceof type"? Having chaining apply to things that are not
*semantically* comparisons is just baffling.

>; this is
> the distinction between language-level features and usage
> recommendations. All comparisons can be chained, and the semantics of
> (X op1 Y op2 Z) will always be ((X op1 Y) and (Y op2 Z)) but with Y
> evaluated only once. That definition is fairly simple, and even though
> it's a little wordy, it makes perfect sense; and the rule "all
> comparisons" is way WAY simpler than "this specific set of chainable
> operators", 

It's the same thing - you've just named that set "comparisons". I don't
think "in" is semantically a comparison at all.