[Zope3-dev] Re: [Zope-dev] Re: tal:on-error is a bare except...

[Jim Fulton]

Tres Seaver wrote:
> Jim Fulton wrote:
> 

...

>> Hm. I wonder if SystemError would be appropriate here.
>> (Zope may abuse SystemError, but we could fix that.)
> 
> 
> RuntimeError exists, but has the wrong bases (StandardError, which 
> derives from Exception).  SystemError has StandardError as its base, too.

I'm not trying to solve the problem of making an exception uncatchable.
If we said that RuntimeError or SystemError (or whatever) shouldn't
be caught by a bare excpt, then we could, with present Python
say that the following is the correct idiom for a bare except:

   try:
       ...
   except:
       if isinstance(sys.exc_info()[1], RuntimeError):
           raise
       ... do what we do for ctachable errors

Jim


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