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It really depends. Usually, you would do something like this in Python: def whatever(some_string): try: return some_string.split() except Attri

It really depends. Usually, you would do something like this in Python: def whatever(some_string): try: return some_string.split() except AttributeError: return some_other_parsing_stuff(some_string) Instead of checking the type of some_string, or seeing if it has the method split. Reason is: it's more straight forward, and it instantly tells the reader this function is meant to handle strings, and it will split them. If it gets a not-string for some reason, oh well, it'll still handle it. You would check for values in a circumstance like this: def dict_breaker(some_dict): if 'items' in some_dict: return parse_some_items(some_dict['items'])

dbaupp 11y ago
The latter isn't actually the typical Python style. As the article discusses, Python generally prefers "EAFP"[1] to "LBYL"[2], e.g. def dict_breaker(some_dict): try: return parse_some_items(some_dict['items']) except KeyError: pass Or even def dict_breaker(some_dict): try: items = some_dict['items'] except KeyError: pass else: return parse_some_items(items) These versions may be more efficient (only have to do one hash and interaction with the hashmap, but this probably won't be visible with integers/short strings), and don't suffer from race conditions in concurrent code with the hashmap being modified between the check and the use (yes, this can occur even with GIL). [1]: https://docs.python.org/2/glossary.html#term-eafp https://docs.python.org/2/glossary.html#term-eafp [2]: https://docs.python.org/2/glossary.html#term-lbyl https://docs.python.org/2/glossary.html#term-lbyl
- kornish 11y ago
  Is there a reason you chose to `pass` instead of the more explicit `return None`? The former seems like it would be less idiomatic since its return value is not explicitly stated.
  - dbaupp 11y ago
    To emulate the parent exactly e.g. maybe it is just the prefix of the "dict_breaker" function and other things happen later if the key can't be found.

dbaupp 11y ago

The latter isn't actually the typical Python style. As the article discusses, Python generally prefers "EAFP"[1] to "LBYL"[2], e.g. def dict_breaker(some_dict): try: return parse_some_items(some_dict['items']) except KeyError: pass Or even def dict_breaker(some_dict): try: items = some_dict['items'] except KeyError: pass else: return parse_some_items(items) These versions may be more efficient (only have to do one hash and interaction with the hashmap, but this probably won't be visible with integers/short strings), and don't suffer from race conditions in concurrent code with the hashmap being modified between the check and the use (yes, this can occur even with GIL). [1]: https://docs.python.org/2/glossary.html#term-eafp https://docs.python.org/2/glossary.html#term-eafp [2]: https://docs.python.org/2/glossary.html#term-lbyl https://docs.python.org/2/glossary.html#term-lbyl

kornish 11y ago
Is there a reason you chose to `pass` instead of the more explicit `return None`? The former seems like it would be less idiomatic since its return value is not explicitly stated.
- dbaupp 11y ago
  To emulate the parent exactly e.g. maybe it is just the prefix of the "dict_breaker" function and other things happen later if the key can't be found.