[Python-Dev] Exception Reorg PEP checked in

[Brett Cannon]

On 8/5/05, Raymond Hettinger <raymond.hettinger at verizon.net> wrote:
> > On 8/4/05, James Y Knight <foom at fuhm.net> wrote:
> > > >        +-- NamespaceError (rename of NameError)
> > > >            +-- UnboundFreeError (new)
> > > >            +-- UnboundGlobalError (new)
> > > >            +-- UnboundLocalError
> > > >
> > >
> > > What are these new exceptions for? Under what circumstances are they
> > > raised? Why is this necessary or an improvement?
> > >
> >
> > Exceptions relating to when a name is not found in a specific
> > namespace (directly related to bytecode).  So UnboundFreeError is
> > raised when the interpreter cannot find a variable that is a free
> > variable.  UnboundLocalError already exists.  UnboundGlobalError is to
> > prevent NameError from being overloaded.  UnboundFreeError is to
> > prevent UnboundLocalError from being overloaded
> 
> Do we have any use cases for making the distinctions.  I have NEVER had
> a reason to write a different handler for the various types of
> NameError.
> 
> Also, everyone knows what a Global is.  Can the same be said for Free?
> I had thought that to be a implementation detail rather than part of the
> language spec.
> 

Perhaps then we should just ditch UnboundLocalError?  If we just make
sure we have good messages to go with the exceptions the reasons for
the exception should be obvious.

-Brett