On Tue, 8 Sep 2015 06:59 pm, Antoon Pardon wrote: > Op 04-09-15 om 02:47 schreef Mark Lawrence: >> On 04/09/2015 01:06, Michael Torrie wrote: >>> On 09/03/2015 01:05 PM, t...@freenet.de wrote: >>> >>>> [The same e.g. with switch statement: add it] >>> >>> Switch is a nice-to-have thing, but definitely not essential. A PEP here >>> (probably already has been several) would at least be read anyway. >>> However, there are several idiomatic ways of accomplishing the same >>> thing that are often good enough and familiar to any Python programmer >>> out there. Since functions are first-class objects, often a dispatch >>> table is the best way to go here. >>> >> >> https://www.python.org/dev/peps/pep-3103/ "A Switch/Case Statement" by >> Guido van Rossum, "Rejection Notice - A quick poll during my keynote >> presentation at PyCon 2007 shows this proposal has no popular support. >> I therefore reject it". >> >> https://www.python.org/dev/peps/pep-0275/ "Switching on Multiple >> Values" by Marc-André Lemburg, "Rejection Notice - A similar PEP for >> Python 3000, PEP 3103 [2], was already rejected, so this proposal has >> no chance of being accepted either." >> > Were those polls, like the poll he once did for the condtional expression? > There the poll indicated no specific proposal had a majority, so for each > specific proposal one could say it didn't have popular support, but the > majority still prefered to have a conditional expression. But at that > time Guido used that poll as an indication there was not enough support.
In the case of conditional expression, there is *no good alternative*. Using if...then statement is too heavyweight, and cannot be used in an expression. Using "flag and true_value or false_value" is buggy -- it fails if true_value is itself false. Refactoring it to a function uses eager rather than lazy evaluation. So there was no existing alternative to a ternary if expression that worked correctly. In the case of case/switch, there is no consensus on what the statement should do, how it should work, what purpose it has, or what syntax it should use. Rather than "there's no alternative to a case statement", the situation was more like "there are many good alternatives to the various different case statements people want". -- Steven -- https://mail.python.org/mailman/listinfo/python-list
