[Luyt]

Hmmm, you have a point there, but what is your proposal to solve it in a correct way, then?

Some problems need a deeply nested control flow and arcane business rules, you have to implement that somehow, and in such a case the method I use looks like the lesser of two evils. I'd rather have some flat ecosystem of meaningful functions than one monolithic deeply nested control structure.

From time to time I like defensive programming, and when I write a function 'frob' that promises to frob something, that function first makes sure that the thing can indeed be 'frobbed', and if not, bails out. This also works well for programs that should be idempotent (although that is a whole other issue).

[anthonyb]

The way I would do it is to push the processing out to functions, too. Something like:

  verdict = get_verdict(the_thing)
  if verdict not in blessedsolutions:
      return

I'd advise against running returns onto the same line - I find it makes it harder to read, particularly when you have a lot of checks like this.

[Luyt]

"The way I would do it is to push the processing out to functions, too."

This is indeed a good idea to isolate code away, but wouldn't alleviate a deeply nested control structure. It would make it somewhat more easier to look at, though.

"I'd advise against running returns onto the same line "

I usually follow PEP8 and place returns and continues on the next line, but the code examples I posted earlier had to be a bit condensed to conserve screen space, that's why ;-)

[anthonyb]

Sometimes your problem space is really just that complex, in which case there's not much you can do, short of writing some sort of business rules engine.