[Python-Dev] PEP 308: "then" "else" for deprecating "and" "or" side effects
mal at lemburg.com
Fri Feb 14 12:41:21 CET 2003
Christian Tismer wrote:
> M.-A. Lemburg wrote:
>> Christian Tismer wrote:
>>> Dear community,
>>> there has been some favor of my silly/simple a then b else c proposal.
>>> Please let me elaborate a little on this, with respect
>>> to the existing "and" and "or operators.
>>> "and" and "or" are two-headed beasts:
>>> At first glance, they pretend to be logical operators.
>>> At second inspection, they do this logic by promoting
>>> one of their operands.
>>> This is not obviously bad, and it is consistant with the logic.
>>> Due to the presence of a real boolean type, we
>>> should ask ourselves if "and" and "or" shouldn't be
>>> deprecated in their current meaning, towards being
>>> "boolean only"?
>> You are forgetting a detail here: "and" as well as "or"
>> are not implemented as operators. "&" and "|" are the
>> boolean operators and these do return boolean values.
> Na, aber!
> You are confusing bitwise orerations which booleans.
Sorry, I meant "&&" and "||".
> 5.10 Boolean operations
> Boolean operations have the lowest priority of all Python operations:
> expression: or_test | lambda_form
> or_test: and_test | or_test "or" and_test
> and_test: not_test | and_test "and" not_test
> not_test: comparison | "not" not_test
> lambda_form: "lambda" [parameter_list]: expression
>> Constructs misusing "and" and "or" for the sake of
>> inlining if-then-else should be reserved for those
>> who know what they're doing (and can live with the
> Hey, did you realize what my message is about?
> I am talking of a better alternative, not
> "and" and "or".
Sure. I was argueing against adding more inlining
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