Python try...except comma vs 'as' in except
The definitive document is PEP-3110: Catching Exceptions
Summary:
- In Python 3.x, using
asis required to assign an exception to a variable. - In Python 2.6+, use the
assyntax, since it is far less ambiguous and forward compatible with Python 3.x. - In Python 2.5 and earlier, use the comma version, since
asisn't supported.
Yes it's legal. I'm running Python 2.6
try: [] + 3except Exception as x: print "woo hoo">>> woo hooUpdate: There is another reason to use the as syntax. Using , makes things a lot more ambiguous, as others have pointed out; and here's what makes the difference. As of Python 2.6, there is multicatch which allows you to catch multiple exceptions in one except block. In such a situation, it's more expressive and pythonic to say
except (exception1, exception2) as erather than to say
except (exception1, exception2), ewhich would still work
the "as" syntax is the preferred one going forward, however if your code needs to work with older Python versions (2.6 is the first to support the new one) then you'll need to use the comma syntax.