New in version 2.5.
The with statement is used to wrap the execution of a block with methods defined by a context manager (see section 3.4.9). This allows common try...except...finally usage patterns to be encapsulated for convenient reuse.
The execution of the with statement proceeds as follows:
Note: The with statement guarantees that if the __enter__() method returns without an error, then __exit__() will always be called. Thus, if an error occurs during the assignment to the target list, it will be treated the same as an error occurring within the suite would be. See step 5 below.
If the suite was exited due to an exception, and the return value from the __exit__() method was false, the exception is reraised. If the return value was true, the exception is suppressed, and execution continues with the statement following the with statement.
If the suite was exited for any reason other than an exception, the return value from __exit__() is ignored, and execution proceeds at the normal location for the kind of exit that was taken.
with_statementfeature has been enabled. It will always be enabled in Python 2.6. This
__future__import statement can be used to enable the feature:
from __future__ import with_statement
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