PEP 308: "then" "else" for deprecating "and" "or" side effects

Christian Tismer tismer at tismer.com
Fri Feb 14 15:25:03 CET 2003


Erik Max Francis wrote:
> Christian Tismer wrote:

[and or]

>>"and" and "or" are behaving like logical operators.
>>They happen to do this by not providing a plain
>>truth value, but by promoting one of their operands.
> 
> 
> They _are_ logical operators.  They just do their logical by returning
> one of the objects, rather than a strict Boolean.  Other languages do
> this, like Lisp; there's nothing inherently wrong with it.  It's also
> way too entrenched to change now.  It's an example of a feature that I
> don't often rely on, but even I, a champion of the Booleans PEP,
> wouldn't think to change their behavior now.

That's fine with me. Note that I do not say that we
should change and and or (ignore my words about
future deprecation). Instead, we should not
abuse them in a way that has nothing to do with an
"and", like the "(a and [b] or [c])[0])" tricks
or the proposed {} escape. These are tricks to make
them behave differently.
I only propose to make these uses explicit
by using "then" and "else" instead.

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