If/then style question

[Ethan Furman]

John Gordon wrote:
> (This is mostly a style question, and perhaps one that has already been
> discussed elsewhere.  If so, a pointer to that discussion will be
> appreciated!)
> 
> When I started learning Python, I wrote a lot of methods that looked like
> this:
> 
> 
>   def myMethod(self, arg1, arg2):
>     if some_good_condition:
>       if some_other_good_condition:
>         if yet_another_good_condition:
>           do_some_useful_stuff()
>           exitCode = good1
>         else:
>           exitCode = bad3
>       else:
>         exitCode = bad2
>     else:
>       exitCode = bad1
>     return exitCode
> 
> 
> But lately I've been preferring this style:
> 
>   def myMethod(self, arg1, arg2):
>     if some_bad_condition:
>       return bad1
>     elif some_other_bad_condition:
>       return bad2
>     elif yet_another_bad_condition:
>       return bad3
>     do_some_useful_stuff()
>     return good1
> 
> I like this style more, mostly because it eliminates a lot of indentation.

As far as if/else goes, I prefer the second style also.

As far as returning bad codes, you are better off raising exceptions:

def myMethod(self, arg1, arg2):
     if some_bad_condition:
         raise Bad1()
     elif some_other_bad_condition:
         raise Bad2()
     elif yet_another_bad_condition:
         raise Bad3()
     do_some_useful_stuff
     # no need to return 'good' code -- success means no problems

~Ethan~