[Python-ideas] Yet Another Switch-Case Syntax Proposal

[Lucas Malor]

On 19 April 2014 06:54, Andrew Barnert abarnert-at-yahoo.com |
python-ideas-at-python.org| <3en9kh2cbt at sneakemail.com> wrote:

>     switch mystring case "spam":
>         process(thingy)
>
> That is not even remotely interpretable as an English sentence. That's not
> a problem for C, but it is for Python.
>

I'll think about a possible solution.


 I don't see how skipping over any elcase but falling through to the next
>>> case is in any way simpler than C.
>>
>> Well, because it's coherent with if-elif. See my last example in my
>> first message.
>>
> No it isn't. An elif clause is embedded in an if statement; there is no if
> clause you can embed on an if statement, just an entirely new and unrelated
> if statement.
>

I can assert, without fear of contradictions, that my proposed syntax is
the closest to the if-elif syntax of all the switch statement proposed
until now in the age of Python.



About off-topic arguments:


bash does not have either ";;&" or ";&"
>

http://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html


Who asked you about list comprehensions or lambdas? What do you think they
> have to do with anything?
> [...]
> I have no idea why you think recursive functions are relevant to anything
> being discussed here.
> [...]your proposal was to treat tuples specially and match all other
> iterables as single values, which means that a generator expression would
> be matched as a single value, meaning it would only match itself. And
> again, I don't understand what the relevance is supposed to be.


I premise that pattern recognition is outside the scope of my switch
proposal. Anyway:

   1. About list comprehensions and lambdas, you talked about assignment
   statements, and AFAIK the only pattern matching things that are somewhat
   related to assignment statement are the possibility to filter a list
   comprehension and the use of lambdas. If you mean something different you
   should be more explicit, instead of saying "what? where? why?"
   2. About recursive function, I wronged. Sorry but it was late.
   3. About generators, you can create a generator, convert it to an
   iterable and unpack it in a case_expr. I could also extend the current
   syntax and support a "generator unpacking". This way you'll have a limited
   alternative to pattern matching in some cases in a switch statement without
   the need to create a static iterable.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20140419/bf268bdd/attachment.html>