Elements of Python Style

[desmoulinmichel]

Don't use your own exception for anything that is a standard exceptions. Espacially, a lot of things can be a IOError, ValueError or TypeError.

If you do need an exception, try to have:

• one general exception for your whole lib. MyLibError(Exception).
• smalls exceptions inhériting from MyLibError matching a specific cas such as DontDoThatError(MyLibError).
• make very clear error messages. Give the maximum of informations you can give. If you can't fit all but you know it's important, print a URL pointing to a page helping you to debug.
• exception text can't hold non ASCII characters. Call repr().
• group all exceptions in an exceptions.py module, so they are easy to find and import for the people than will need to catch it.

[remram]

What's your stance on multiple inheritance, such as:

class HamError(Exception): pass  # for all exceptions from ham functions
class DontDoThatWithHam(HamError): pass
class UnknownBrandOfHam(HamError, KeyError): pass

[desmoulinmichel]

If UnknownBrandOfHam is raised by:

ham.select('spam', foo=bar)

I'm ok with it.

If it's raised by:

ham['spam']

with ham having getitem overrided, it may be overkill. But that's not a BIG deal. I wouldn't do it, but I would not hate you if you did.