+ 2

How to switch?

Hello Pythoneers! I am trying to write a program for ATM that accepts from user a choice of operation and executes an operation, which is basically a method. As we know there is no switch case in Python. SO how to handle it without it? As piece of script you can find below: https://code.sololearn.com/cWH9ofLI40Ze

14th Feb 2018, 3:52 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
12 odpowiedzi
+ 4
# Simply chain 'if' and 'elif' (else if) statements: if choice == 1: print('choice 1') elif choice == 2: print('choice 2') elif choice == 3: print('choice 3') elif choice == 4: print('choice 4') # or you can define a dict (or list in case of continuous numeric keys) containing function to execute: def onchoice1(): print('choice 1') def onchoice2(): print('choice 2') def onchoice3(): print('choice 3') def onchoice4(): print('choice 4') choices = { 1: onchoice1, 2 : onchoice2, 3 : onchoice3, 4 : onchoice4 } choices[choice]()
14th Feb 2018, 5:33 PM
visph
visph - avatar
+ 4
hello Saidamamad brother ! i am from tajikistan do you have viber or imo
22nd Jul 2018, 1:05 AM
Oyatullo Sangov
Oyatullo Sangov - avatar
+ 2
I did this task using C# once, but I need to learn Python now. It is a little bit confusing for me (
14th Feb 2018, 3:53 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
+ 2
# Lambda are useful to define short functions, so in such case as my examples, lambda are useful to avoid defining named function. # On the other hand, in your last example lambdas are used only to define a call to another function: you could do better with: return { 1 : ATM.checkBalance, 2: ATM.withdraw, 3: ATM.deposit, 4: ATM.exitProgram, }.get(choice,ATM.errorOccured)()
14th Feb 2018, 7:02 PM
visph
visph - avatar
+ 2
Practice, practice and practice again is the key... with curiosity: at each new problem to solve, you will search solutions, reading stuff, discovering new language features, and so step by step you will get more ideas for next problems to solve ;)
14th Feb 2018, 7:10 PM
visph
visph - avatar
+ 2
Thank you very much!!! 🙏
14th Feb 2018, 8:18 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
+ 1
@visph thanks a lot! That one works! I did similar to that but in dictionary I wrote the parantheses along with the method name, so when the program run, the methods in the dictionary are executed 😂 which is unwanted. choices[choice] () is amazing trick! 😊👍
14th Feb 2018, 6:41 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
+ 1
And I found a tutorial in youtube, which shows a good way also by defining a class method: @classmethod def operation(cls, choice): return{ 1: lambda: ATM.checkBalance(), 2: lambda: ATM.withdraw(), 3: lambda: ATM.deposit(), 4: lambda: ATM.exitProgram(), }.get(choice,lambda: ATM.errorOccured())() while(True): try: choice = int(input('Operation mode: ')) except: ATM.errorOccured() continue; ATM.operation(choice)
14th Feb 2018, 6:46 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
+ 1
It use a temporary dict with lambda functions under the hood ;) Use of lambda could be a good idea (depending on context), but use of temporary litteral dict is not really, even if the lack of efficiency doesn't have a real impact in almost contexts ^^
14th Feb 2018, 6:50 PM
visph
visph - avatar
0
So using lambda should be avoided in this case? Didn't get you well :(
14th Feb 2018, 6:54 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
0
Thank you very much, @visph! I am very week for these kind of tricks :( I don't know how to get like these ideas for problem solving :)
14th Feb 2018, 7:06 PM
Saidmamad Gulomshoev
Saidmamad Gulomshoev - avatar
0
it is corret
15th Feb 2018, 9:00 PM
iuriev