Musings: Using decorators to reduce duplicate exception handling
J Kenneth King
james at agentultra.com
Wed Feb 18 00:12:57 CET 2009
I recently started a project called TracShell
(http://code.google.com/p/tracshell) where I make heavy use of the
xmlrpclib core module.
When the number of RPC calls was small, wrapping each call in try/except
was acceptable. However, this obviously will duplicate code all over the
place. There are only ever two exceptions that the module itself will
throw: xmlrpclib.ProtocolError and xmlrpclib.Fault -- both very useful,
but not show stoppers.
To combat the duplication, my clever idea was to use a function
decorator to wrap any function that used xmlrpclib calls:
A decorator to catch typical xmlrpclib exceptions
def wrapped(*args, **kwargs):
return fn(*args, **kwargs)
except xmlrpclib.ProtocolError, e:
print "There was a problem communicating with the server."
print "URL: %s" % e.url
print "Headers: %s" % e.headers
print "Error code: %d" % e.errcode
print "Error message: %s" % e.errmsg
print "Please file a report with the TracShell developers."
except xmlrpclib.Fault, e:
print "A fault ocurred"
print "Fault code: %d" % e.faultCode
print "Fault string: %s" % e.faultString
print "If you think this message is the result of an error,"
print "please file a report with the TracShell developers."
Maybe I could rename the decorator to something meaningful, but besides
that it works pretty well. Now any function I write in my class that
uses RPC calls can be wrapped by this decorator and have the exception
handling done in a uniform way for these particular exceptions.
I was just curious if other Pythonistas out there used the same idea or
have a better one. Thoughts?
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