failureaction 1.0a1

Decorators for actions executed in case of an exception

This package is intended to provide decorators which execute custom actions in case of exceptions. Let’s see an example:

First we need an object with some methods. These methods we decorate with the PrintOnFailure-decorator. This simple example decorator prints a given message in case of an exception.

>>> from failureaction import ConflictError
>>> from failureaction import PrintOnFailure
>>> class TestOb(object):
...
...    @PrintOnFailure(msg='Some numeric calculation went wrong!')
...    def divide(self, a, b):
...        return a/b
...
...    @PrintOnFailure()
...    def doraise(self):
...        raise ConflictError

We have two methods. One (divide) does numerical division of two numbers and another raises a custom defined ConflictError. Now let’s see the methods in action:

>>> ob = TestOb()
>>> ob.divide(4, 2)
2

>>> ob.divide(42, 0)
Some numeric calculation went wrong!

>>> ob.doraise()
Traceback (most recent call last):
...
ConflictError

The ActionOnFailure decorator provided by the module is intended to be overriden by a custom class. Like this:

>>> from failureaction import ActionOnFailure
>>> class MailOnFailure(ActionOnFailure):
...
...     def __init__(self, subject):
...         self.subject = subject
...
...     def _doaction(self, context, e):
...         """ send a mail, if an exception was raised """
...         print "Subject:", self.subject
...         print e

>>> class TestOb2(object):
...
...     @MailOnFailure(subject='An error occured')
...     def critical(self):
...         import _not_existent_hopefully_

>>> ob2 = TestOb2()
>>> ob2.critical()
Subject: An error occured
No module named _not_existent_hopefully_