The reason I say this is because you can apply his points to any programming construct, so if you believe the concept of switch is good (regardless of how poorly other languages implement it) then it should be added.

Anyone who says otherwise is bias based on their emotions for some strange reason.

def handle_one():
pass
def handle_two():
pass

someVariable = ‘case1′
switchcase = {
‘case1′:handle_one,
‘case2′:handle_two
}[someVariable]()

- Paddy.

Do you honestly think that the dispatch method is as intuitive as a switch statement to a non-programmer? (If yes, then that is all you need to answer) I don’t even think it is as intuitive to a python programmer since i’ve been a python programmer for a long time and i still can spot a switch statement’s intentions much quicker, not to mention find the right method being called, since while python enforces indenting for standard blocks, it can do nothing about dictionary’s contents.

Note also that the list of tips is very generic and most would apply equally well to pretty much any other language, but definitely not the dispatch. The point about not carrying bad patterns from other languages is already explicited in another point. The dispatch hint just sits by itself, as a non-obvious solution to a problem that people will obviously want to solve.

But my main objection was to the “pretty neat”, which pervades the c.l.p newsgroup, exulting on the idioms that were invented to paper over the language’s flaws. It’s as if the ‘if’ statement wouldn’t have been included, they would defend the use of the dispatch mechanism for this too. If the language can afford a ‘with’, it can definitely afford a ‘switch’ or a ‘case’ or a ‘when’ (i like when best). It is very far from bloated still.

- Paddy.

More importantly, the fact that most leftover cases are large where whatever has to be called is big enough to deserve their own function is orthogonal to my objection, since even if you have to call a function, it is better to do it inside the switch because the code is semantically clearer (having a switch doesn’t prevent the cases from being function calls). When any programmer sees a switch statement it is obvious what is going on.

The dict method is not obvious. I even tend to write it in the if – elif – elif sometimes because of this. Note that it is perfectly possible to use the dict semantics in pretty much every other language, but it is rarely used outside of python, afaik.

A less-important problem with the dict dispatch method is that all the functions being dispatched have to have the same signature, which either forces you to write functions just for the switch statement, regardless of whether they could have been reused from elsewhere, or use partials/currying and thus add another bit of trickiness for something that should be in the language in the first place.

Finally, a switch statement to me seems more pythonic: there should be one obvious way to do it. The fact that someone felt that something as basic as the dispatch method needed to be added a tips-and-tricks list is a clear sign that it is failing the obvious criteria.