`if key in dict` vs. `try/except` – which is more readable idiom?

by

Exceptions are not conditionals.

The conditional version is clearer. That’s natural: this is straightforward flow control, which is what conditionals are designed for, not exceptions.

The exception version is primarily used as an optimization when doing these lookups in a loop: for some algorithms it allows eliminating tests from inner loops. It doesn’t have that benefit here. It has the small advantage that it avoids having to say "blah" twice, but if you’re doing a lot of these you should probably have a helper move_key function anyway.

In general, I’d strongly recommend sticking with the conditional version by default unless you have a specific reason not to. Conditionals are the obvious way to do this, which is usually a strong recommendation to prefer one solution over another.

More Related Contents:

  1. What does if __name__ == "__main__": do?
  2. How does collections.defaultdict work?
  3. Nested defaultdict of defaultdict
  4. Pairs from single list
  5. Get the key corresponding to the minimum value within a dictionary
  6. Is there a clever way to pass the key to defaultdict’s default_factory?
  7. How to convert defaultdict to dict?
  8. Format string unused named arguments [duplicate]
  9. Can’t pickle defaultdict
  10. Surprising results with Python timeit: Counter() vs defaultdict() vs dict()
  11. Python defaultdict and lambda
  12. Python nested looping Idiom
  13. Too many if statements
  14. What does if __name__ == “__main__”: do in Python?
  15. Python idiom to return first item or None
  16. Python list comprehension – want to avoid repeated evaluation
  17. Checking a nested dictionary using a dot notation string “a.b.c.d.e”, automatically create missing levels
  18. Collections.defaultdict difference with normal dict
  19. Python “Every Other Element” Idiom [duplicate]
  20. What is the clojure equivalent of the Python idiom “if __name__ == ‘__main__'”?
  21. How to get rid of ValueError: could not convert string to float
  22. change column name in pandas, which will be used to change name for 1 column
  23. Getting a list of all subdirectories in the current directory
  24. ImportError: Cannot import name X
  25. Calling variable defined inside one function from another function
  26. Split a generator into chunks without pre-walking it
  27. Checking if list is a sublist
  28. python requests.get() returns improperly decoded text instead of UTF-8?
  29. Python passing list as argument
  30. __init__ as a constructor?

Leave a Comment