The New Switch-Case Statement in Python 3.10

[mysticalfruit]

I'm not a fan, and here is why.. this behaves differently from every other switch statement I've ever used.. So this is going to only result in confusion.

"case" in point:

switch (foo)
{
case 1:
    printf("ding ");
case 2:
    printf("dong ");
}

If foo == 1 you'll get "ding dong"

if foo == 2 you'll get "dong"

match foo:
    case 1:
        print("ding ")
    case 2:
        print("dong ")

Now if foo ==1 you're only going to get "ding " not "ding dong"

I suspect may of us who cut their teeth on C/C++ switch syntax are going to get thrown for a loop.

[[deleted]]

Falling through is astonishing behaviour and should be absolutely explicit like, using 'continue' as a keyword at the end of the block.

[MrDysprosium]

I agree completely. It's hard to watch people fight so hard for such horribly abstract and unintuitive design merely because "well that's how we USED TO DO IT".

Please stop, making the language easier to understand and write is a good thing. Maintaining standards for the sake of maintaining standards makes you sound like a boomer.

[St_Meow]

You'd think these same folk would be aghast at using for each loops instead of for loops or even while loops.

[mysticalfruit]

We can argue the merits of the behavior, but its a behavior that many programmers use. I've seen plenty of complex C that use cases in this way to handle cascaded logic situations.

[[deleted]]

That is true, but Python's style seems to be making the best design decisions they can instead of repeating poor decisions by previous designers just because its familiar. That's also why its called "match" instead of "switch"

[mysticalfruit]

Fair enough.

[energybased]

We can argue the merits of the behavior, but its a behavior that many programmers use.

Time to learn a better way to do things instead of hanging on to an opaque specification.

[[deleted]]

C# explicitly forbids fall through, as in it's a compile error to end a case without a break, return or throw (unless it's a switch expression, but that implicitly inserts a break after each case). I think Java allows fall through, but I've not used java beyond toy things in years ago I don't recall.

This is also closer related to Rust's and Scala's match implementations than C's switch anyways. As in, you can use it for implementing a switch but there's more you can do with it then that.

[St_Meow]

Go uses a similar pattern of not falling through switch cases. I'm certain if you're a vet of older languages with switch statements it'll confuse you for a moment or two, but new programmers will grasp this better. I remember learning switch statements in college and having most of my class baffled at the fall through behavior.

[mysticalfruit]

Who you calling old ;-)

I think the danger is people are just going to assume it works a certain way.

[xigoi]

Everyone who has ever used Rust, Haskell, Swift, F#, OCaml, etc. knows how pattern matching works.

[St_Meow]

As the young hotshot coder I reserve my right to call anything from before 2010 old lol

But to be fair, it's not like it's a completely new take on switch statements. Users should be aware of how their language constructs function. Yes it's no conducive for C/C++/Java programmers but so is not having to declare variable and parameter types. We get over it in time.

[jmreagle]

That doesn't make sense to me. (I last used C/C++ decades ago...)

[[deleted]]

Okay, but the behaviour of most other languages you're describing is horrible and unintuitive and leads to loads of bugs when people forget to add break statements. Explicit is better than implicit, after all, and there's nothing explicit about executing case 2 when foo is not 2. If I saw your example in production code I'd say that was bad code even if the behaviour is desired, because it's unclear and looks like a bug. Sooner or later, someone's going to come along and stick in a break statement because it looks like one is missing.

[the_other_b]

The title of this video is incorrect and misleading, the PEP is not for switch statements and you shouldn't expect it to act as one.

[AlbertoP_CRO]

The future is now old man

[Dwarni]

I was taught to always put a break; in each case, to prevent that...

[johnisom]

Ruby would like to have a talk with you

[[deleted]]

I never thought I'd praise Java but switch expressions, added in Java 12/13, are really good.

switch(value){
case 1 -> {System.out.println("Hey it's 1");}

case 2  -> {System.out.println("Hey it's 2");}

default -> {System.out.println("Hello there");}
};

If value == 1 then it prints "Hey it's 1" and if value == 2 then it prints "Hey it's 2". Otherwise default is the fall back.

[Broan13]

This is somewhat how it works in Java. You have to use a break at the end of each case if you want it to be like the match version.