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Update ErrorHandler docstring.

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This commit is contained in:
Blake Griffith 2016-07-05 21:59:00 -05:00
parent 79c602ffc8
commit 277b7a89f1
1 changed files with 16 additions and 9 deletions
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25
certbot/error_handler.py
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@ -21,19 +21,26 @@ _SIGNALS = ([signal.SIGTERM] if os.name == "nt" else
class ErrorHandler(object):
"""Registers functions to be called if an exception or signal occurs.
"""Context manager for running code that must be cleaned up on failure.
This class allows you to register functions that will be called when
an exception (excluding SystemExit) or signal is encountered. The
class works best as a context manager. For example:
The context manager allows you to register functions that will be called
when an exception (excluding SystemExit) or signal is encountered. Usage:
with ErrorHandler(cleanup_func):
handler = ErrorHandler(cleanup1_func, *cleanup1_args, **cleanup1_kwargs)
handler.register(cleanup2_func, *cleanup2_args, **cleanup2_kwargs)
with handler:
do_something()
If an exception is raised out of do_something, cleanup_func will be
called. The exception is not caught by the ErrorHandler. Similarly,
if a signal is encountered, cleanup_func is called followed by the
previously registered signal handler.
Or for one cleanup function:
with ErrorHandler(func, args, kwargs):
do_something()
If an exception is raised out of do_something, the cleanup functions will
be called in last in first out order. Then the exception is raised.
Similarly, if a signal is encountered, the cleanup functions are called
followed by the previously received signal handler.
Each registered cleanup function is called exactly once. If a registered
function raises an exception, it is logged and the next function is called.