How to exit an if clause

Question

What sorts of methods exist for prematurely exiting an if clause    There are times when I m writing code and want to put a break statement inside of an if clause  only to remember that those can only be used for loops   Lets take the following code as an example   if some condition            if condition a           do something          and then exit the outer if block           if condition b           do something          and then exit the outer if block      more code here   I can think of one way to do this  assuming the exit cases happen within nested if statements  wrap the remaining code in a big else block  Example   if some condition            if condition a           do something          and then exit the outer if block    else                    if condition b               do something              and then exit the outer if block        else               more code here   The problem with this is that more exit locations mean more nesting indented code   Alternatively  I could write my code to have the if clauses be as small as possible and not require any exits   Does anyone know of a good better way to exit an if clause   If there are any associated else-if and else clauses  I figure that exiting would skip over them

User · Answer

use return in the if condition will returns you out from the function  so that you can use return to break the the if condition

User · Answer

You can emulate goto s functionality with exceptions   try        blah  blah           raise MyFunkyException as soon as you want out except MyFunkyException      pass   Disclaimer  I only mean to bring to your attention the possibility of doing things this way  while in no way do I endorse it as reasonable under normal circumstances  As I mentioned in a comment on the question  structuring code so as to avoid Byzantine conditionals in the first place is preferable by far   -

User · Answer

So here i understand you re trying to break out of the outer if code block  if some condition              if condition a           do something          and then exit the outer if block                if condition b           do something          and then exit the outer if block   more code here   One way out of this is that you can test for for a false condition in the outer if block  which will then implicitly exit out of the code block  you then use an else block to nest the other ifs to do something  if test for false        Exit the code which is the outer if code   else      if condition a            Do something      if condition b            Do something

User · Answer

while some condition            if condition a           do something        break           if condition b           do something        break      more code here    break

User · Answer

Here s another way to handle this  It uses a single item for loop that enables you to just use continue  It prevents the unnecessary need to have extra functions for no reason  And additionally eliminates potential infinite while loops   if something      for   in  0             Get x         if not x              continue            Get y         if not y              continue            Get z         if not z              continue            Stuff that depends on x  y  and z

User · Answer

For what was actually asked  my approach is to put those ifs inside a one-looped loop  while  True       if  some condition                       if  condition a                 do something               and then exit the outer if block             break                     if  condition b                 do something               and then exit the outer if block             break           more code here       make sure it is looped once     break   Test it   conditions    True False  some condition   True  for condition a in conditions      for condition b in conditions          print   n           print  with condition a   condition a          print  with condition b   condition b          while  True               if  some condition                   print  checkpoint 1                   if  condition a                         do something                       and then exit the outer if block                     print  checkpoint 2                       break                 print   checkpoint 3                   if  condition b                         do something                       and then exit the outer if block                     print  checkpoint 4                       break                 print   checkpoint 5                     more code here               make sure it is looped once             break

User · Answer

There is another way which doesn t rely on defining functions  because sometimes that s less readable for small code snippets   doesn t use an extra outer while loop  which might need special appreciation in the comments to even be understandable on first sight   doesn t use goto       and most importantly let s you keep your indentation level for the outer if so you don t have to start nesting stuff   if some condition            if condition a           do something        exit if True   and then exit the outer if block if some condition and not exit if    if and only if exit if wasn t set we want to execute the following code      keep doing something    if condition b           do something        exit if True   and then exit the outer if block if some condition and not exit if       keep doing something   Yes  that also needs a second look for readability  however  if the snippets of code are small this doesn t require to track any while loops that will never repeat and after understanding what the intermediate ifs are for  it s easily readable  all in one place and with the same indentation   And it should be pretty efficient

User · Answer

may be this   if some condition and condition a           do something elif some condition and condition b               do something              and then exit the outer if block elif some condition and not condition b               more code here else        blah if

User · Answer

Generally speaking  don t  If you are nesting  ifs  and breaking from them  you are doing it wrong   However  if you must   if condition a     def condition a fun           do stuff          if we wanna escape             return    condition a fun   if condition b     def condition b fun           do more stuff          if we wanna get out again             return    condition b fun     Note  the functions don t HAVE to be declared in the if statement  they can be declared in advance    This would be a better choice  since it will avoid needing to refactor out an ugly if then later on

User · Answer

The only thing that would apply this without additional methods is elif as the following example a     yearly    monthly    quartly    semiannual    monthly    quartly    semiannual    yearly     start the condition if  monthly  in b       print  monthly    elif  quartly  in b       print  quartly    elif  semiannual  in b       print  semiannual    elif  yearly  in b       print  yearly    else       print  final

User · Answer

from goto import goto  label  if some condition            if condition a           do something          and then exit the outer if block        goto  end           if condition b           do something          and then exit the outer if block        goto  end      more code here  label  end    Don t actually use this  please

User · Answer

Effectively what you re describing are goto statements  which are generally panned pretty heavily  Your second example is far easier to understand    However  cleaner still would be   if some condition            if condition a         your function1      else         your function2         def your function2       if condition b           do something          and then exit the outer if block    else           more code here

User · Answer

This method works for ifs  multiple nested loops and other constructs that you can t break from easily    Wrap the code in its own function   Instead of break  use return   Example   def some function        if condition a            do something and return early                     return             if condition b            do something else and return early                     return             return  if outer condition              some function

[python] How to exit an if clause

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