Unified try Statement Syntax

When combined like this, the try statement must have either an except or a finally, and the order of its parts must be like this:

try -> except -> else -> finally

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where the else and finally are optional, and there may be zero or more except, but there must be at least one except if an else appears. Really, the try statement consists of two parts: excepts with an optional else, and/or the finally.

In fact, it’s more accurate to describe the merged statement’s syntactic form this way (square brackets mean optional and star means zero-or-more here):

try:                               # Format 1
    statements
except [type [as value]]:          # [type [, value]] in Python 2
    statements
[except [type [as value]]:
    statements]*
[else:
    statements]
[finally:
    statements]

try:                               # Format 2
    statements
finally:
    statements

Because of these rules, the else can appear only if there is at least one except, and it’s always possible to mix except and finally, regardless of whether an else appears or not. It’s also possible to mix finally and else, but only if an except appears too (though the except can omit an exception name to catch everything and run a raise statement, described later, to reraise the current exception). If you violate any of these ordering rules, Python will raise a syntax error exception before your code runs.