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PEP-308 a "simplicity-first" alternative

Christian Tismer tismer at tismer.com
Wed Feb 12 21:50:12 EST 2003 
Terry Reedy wrote:
> "Bjorn Pettersen" <BPettersen at NAREX.com> wrote in message
> news:mailman.1045095195.25260.python-list at python.org...
> 
>>From: Bengt Richter [mailto:bokr at oz.net]
>>
>>>I think I have an answer:
>>>    result = cond and {true_value} or false_value
> 
> 
>>Yes, we got you the first three times <wink>. Your proposal
>>1. Doesn't give any indication that the expression is
>>   a selection (i.e. the same as x and y or b).
> 
> 
> Given that 'and' and 'or' are best described as conditional selection
> operators (explaining this is another post not yet written), it is
> straightforward that together they form a conditional selection
> expression.

I think I'm posting evolving messages about the
same thing, but I more and more come to an insight:

'and' and 'or' are logical selection operators.
They use the value of two objects to decide which
one to carry on. Their visual appearance includes
the logical operation on the arguments in a way,
which is the reason for their names.

If we now modify the true_value to become true all
the time, then this is an abuse of the and operator,
since it is no longer doing what it says, it is only
carrying the right value's wrapper if the left value
is true.
This is a complete abuse of the language, and we should
refuse to create work-arounds for it to make it work.

"x and y or z" as a spell of "if x then y else z"
is know to be wrong. But perfectly valid, if it is really
meant in its logical sense (what it seldom is).
"x and {y} or z" is a correct heal of the wrong logic,
but it abuses "and" and its reader, since and is not
intended to do a left test only. Being used like that,
"and" is the wrong name, since we are not intending to
"and" anything, we want a "then".

 From a logical POV, the correct spelling of a logical
"if a then b" construct would translate to "not a or b".
But this works in Pascal, not in Python, since the truth
operators have to carry their original operators.

I think this whole mixture of logic with objects is broken.

ciao - chris
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