svinota / cx Goto Github PK

Example from cxnet/netlink/core.py:253:

if (msg.hdr.type == NLMSG_NOOP):
    msg = None
elif (msg.hdr.type == NLMSG_ERROR):
    error = nlmsgerr.from_address(addressof(msg.data))
    raise Exception("Netlink error %i" % (error.code))

Why raising Exception is a bad practice? because

• You can't catch this particular exception in your code -- except Exception will simply catch everything, including the exception above.
• It doesn't subclass cxnet.BaseException or something, so you can't catch all cxnet-related exceptions as well.
• Returning error code as a string is hardly helpful, because to match the error against errno.* codes, you have to parse it out first.

Here's what I suggest:

class CXNetException(Exception): pass

class NetlinkError(CXNetException): pass

# ...

if (msg.hdr.type == NLMSG_NOOP):
    msg = None
elif (msg.hdr.type == NLMSG_ERROR):
    error = nlmsgerr.from_address(addressof(msg.data))
    raise NetlinkError(error.code, "<human readable explanation>")

We should turn the cx repo into several separate repos -- cxnet and so on -- to ease maintenance tasks like pip distribution and milestones management.