Where is "switch" statement ? Do nobody needs it ?

[metulburr]

with and as should be used on every file operations with built-in open(). In fact it is preferred to do this

1 2	with open('output.txt', 'w') as f:     f.write('Hi there!')

rather than the old

1 2 3

f = open('output.txt', 'w') f.write('Hi there!') f.close()

because people forget to close the file as well as you can do multiple files such as

1	with open(newfile, 'w') as outfile, open(oldfile, 'r', encoding='utf-8') as infile:

So with and as are used quite often.

I really often use it. Maybe as often, as if-else construction...

When would you determine you need a switch over if/else or python dictionary method?

The Zen of Python

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

You can fine more info on their reasoning to switch statement
switch statement
https://www.python.org/dev/peps/pep-3103/

[vlad1777d]

Thanks =)

[nilamo]

I'm still not sure why you're using a switch, though.  Even in javascript, it's horribly underpowered.  If it was a language like haskell or rust, sure go nuts (rust calls it match instead of switch), as those languages use pattern matching, making it much more useful.

For example, if you wanted to convert something like this to a switch...

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choice = int(input("give me a number!  "))   if choice >=0 and choice < 10:     print("0-9") elif choice > 0:     print(">= 10") else:     print("negative")

...the switch would look like this:

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choice = int(input("number?  "))   switch choice:     case 0:     case 1:     case 2:     case 3:     case 4:     case 5:     case 6:     case 7:     case 8:     case 9:         print("0-9")         break     default:         if choice < 0:             print("negative")         else:             print(">= 10")         break

With pattern matching, which javascript doesn't support, it'd be simple:

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choice = int(input("number: "))   match choice:     range(0, 10) => lambda num: print("0-9"),     lambda num: num > 0 => lambda num: print(">= 10"),     _ => lambda num: print("< 0")

[Larz60+]

It seems to me the cleanest and easiest method is a dictionary with function or method addresses that
can be executed directly from the key:

1	dictname[key]()

[nilamo]

I think the dict->function approach is fine for this, but it still misses the pattern matching aspect.  Check out this snippet from the Rust docs: https://rustbyexample.com/flow_control/match.html

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fn main() {     let number = 13;     // TODO ^ Try different values for `number`       println!("Tell me about {}", number);     match number {         // Match a single value         1 => println!("One!"),         // Match several values         2 | 3 | 5 | 7 | 11 => println!("This is a prime"),         // Match an inclusive range         13...19 => println!("A teen"),         // Handle the rest of cases         _ => println!("Ain't special"),     }       let boolean = true;     // Match is an expression too     let binary = match boolean {         // The arms of a match must cover all the possible values         false => 0,         true => 1,         // TODO ^ Try commenting out one of these arms     };       println!("{} -> {}", boolean, binary); }

[Larz60+]

Off subject, but:

1	let number = 13;

reminds me of Dartmouth Basic
but I see your point

[nilamo]

Javascript also uses let, lol. 

With newer versions, every variable should be either let, or const.  var should almost never be used for new code.

[vlad1777d]

@nilamo, seems, that's the same like in Coffeescript.
From reference:

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switch day   when "Mon" then go work   when "Tue" then go relax   when "Thu" then go iceFishing   when "Fri", "Sat"     if day is bingoDay       go bingo       go dancing   when "Sun" then go church   else go work

How I used it:

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switch current_json.message     when "receive_and_answer_secret_question"         do gatekeeper.ask___secret_question     when "login_successful"         alert "Login successfull.             \nAsking main menu page"         document.location = "/main_menu/main_menu_page/"     when "login_failed"         alert "Login failed.             \nPlease, check username and password."

How I used it too:

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switch document.location.host     when "vk.com"         switch document.location.pathname             when "/"                 report_to_server = "login_page_general without_anything_other"             when "/login"                 if document.location.search.includes "act=mobile"                     report_to_server = "login_page_general after_logging_out"                 else if document.location.search.includes "act=blocked"                     report_to_server = "login_page_general_error account_blocked"                 else                     report_to_server = "login_page_general with_login_after_slash"             when "/restore"                 if document.location.search.includes "act=cancel"                     report_to_server = "login_page_general_error login_data_changed"                 else                     report_to_server = "error_page"             when "/login.php"  # can be redirected to news or to login_error page                 setTimeout main_function, 5000                 return null             when "/feed"                 report_to_server = "news_page"             when "/blank.html"                 setTimeout main_function, 5000                 return null             else                 report_to_server = "other_page"     when "oauth.vk.com"         switch document.location.pathname             when "/authorize", "/oauth/authorize"                 if document.getElementsByClassName("oauth_app_photo").length > 0                     # earlier was: document.body.innerHTML.includes "запрашивает доступ к Вашему аккаунту"                     report_to_server = "api_app_rights_request_page"                 else if document.getElementsByClassName("oauth_captcha").length > 0                     report_to_server = "captcha_asked"                 else                     report_to_server = "login_page_api"             else                 report_to_server = "other_page"     when "api.vk.com"         if (document.location.pathname == "/blank.html") and (document.location.hash.includes "access_token=")             report_to_server = "api_logined_page"         else             report_to_server = "other_page"     else         report_to_server = "other_page"

It's even more often-used statement than "if" =)

Here I writed my thoughts about good syntax and how to implement it: https://github.com/vlad1777d/pythonscript
If somebody interested - you can tell your opinion about it.
Readme is not finished, especially, I had not written about "switch", but I will =)
I think, that "switch" and "if" must be the same like in Coffeescript, to be able to do so:

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a = switch b     when 4         8 + 8     when 8, 9, 10          somevar   a = if b > 0     4 else     8