[Python-Dev] GeneratorExit inheriting from Exception

[Barry Warsaw]

On Sun, 2006-03-19 at 17:31 +1000, Nick Coghlan wrote:

> With PEP 352 (tweaked to move GeneratorExit out from under Exception):
>    - "except:" continues to mean catch everything
>    - "except Exception:" now does the right thing
>    - inheriting from Exception continues to be correct for user exceptions
>    - errors may choose to inherit from one of the existing Errors instead
> 
> With Barry's proposed hierarchy:
>    - "except:" continues to mean catch everything
>    - "except Exception:" continues to do the wrong thing
>        - all code has to change to do "except Error:" instead
>    - inheriting from Exception becomes incorrect for user exceptions
>        - all code has to change to inherit from Error instead
>    - non-error user exceptions (such as completion of a search using nested
>      loops) have no clear parent to inherit from (both Error and Exception
>      are wrong, albeit for different reasons.
> 
> The additional pain required in order to have 'Exception' at the root of the 
> hierarchy just isn't worth it.

One quibble.  Since the term used for the general concept of something
that is raised and caught is "exception" and since all the raise-able
objects live in a module called "exceptions", it is confusing that
"except Exception" will not catch all exceptions.

-Barry

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