[Zope-CMF] Re: [dev] some questions regarding Exceptions

[Yuppie]

Hi!


Dieter Maurer wrote:

> Yuppie wrote at 2003-9-16 12:59 +0200:
>  > ...
>  > After rereading the python docs, I think the root exception has to be
>  > 
>  >    class CMFError(Exception):
>  > 
>  > Thats the easy part.
> 
> I do not think, it should derive from "Exception" but from
> "StandardError".
> 
> There are exceptions that are not errors, e.g. ConflictError.
> It should be easy to catch just errors with "except StandardError"
> and let non-error exceptions through.

Look at POSException.py:

   class POSError(StandardError): ...
   class TransactionError(POSError): ...
   class ConflictError(TransactionError): ...

ConflictError is derived from StandardError! "except StandardError" 
isn't saver than a bare except.

> This is widely not adhered, too, but we may start with it.

Are you sure thats the Right Way?

<http://www.python.org/doc/current/tut/node10.html#SECTION0010500000000000000000>
shows an example with

   class Error(Exception): ...

<http://www.python.org/doc/current/lib/module-exceptions.html> says:

StandardError:=The base class for all built-in exceptions except 
StopIteration and SystemExit.


Cheers,
	Yuppie