If/then style question

[Kev Dwyer]

On Thu, 16 Dec 2010 21:49:07 +0000, 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
> 
> 

Another way to look at this is as question of object-oriented style, as you
 are using a method in your example...

Arguably, rather than branching your code based on the arguments being 
passed to your method, you can embody the required behaviour in subclasses
of your class, and at runtime just use an object that "does the right 
thing".  Of course, you end up writing the same branching in some factory 
object instead, but at least it isn't cluttering up your business logic 
any longer.  Trying to write an OO-style program without using any if 
statements in the business logic can be an interesting exercise, albeit 
not a terribly realistic one.

Apologies if your choice of a method for your example was entirely
incidental to your question :)

Kev