[Python-ideas] raising an exception type doesn't instantiate it until it gets caught

[Gregory P. Smith]

On Tue, Nov 1, 2011 at 1:15 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:

>
> No, the traceback info is added by the eval loop itself. Remember that
> when you raise an exception *type* (rather than an instance), the
> exception doesn't get instantiated until it gets caught somewhere -
> the eval loop maintains the unwinding stack for the traceback as part
> of the thread state until it is time to attach it to the exception
> object.
>

I did not know that.  Is there a good reason for doing this?  It seems
unnecessarily complicated.

-gps
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