A million things can go wrong, and there are several ways to succeed. You want to check for the ways that can succeed and continue on as soon as one of them does. You want the non-local flow of control that exceptions provide, but you need it for both success and failure.
Python, 17 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | def doLoginAction(self):
"""Try to actually log the user in."""
class PasswordAccepted(Exception): pass
try:
if check_password(): # This may raise KeyError.
raise PasswordAccepted
do_more_expensive_work()
and_even_more_expensive_work()
if check_other_password(): # This may raise KeyError.
raise PasswordAccepted
raise KeyError
except KeyError:
self.setError("Invalid username or password.")
return
except PasswordAccepted:
pass
continue_successfully()
|
Tags: shortcuts
