[Python-3000] Transition to Python 3's raise syntax

Phillip J. Eby pje at telecommunity.com
Sat Feb 24 23:23:53 CET 2007

At 03:27 PM 2/24/2007 -0600, Collin Winter wrote:
>Are "new-style" except clauses the ones spelled "except E as NAME" while
>"old-style" ones are spelled "except E, NAME"?


>What happens in this case:
>e = Exception()
>e.__traceback__ = T1
>raise Exception, e, T2
>Which traceback takes precedence? My preference would be to raise an
>exception in this case.

Hm.  How would you get that case in normal code?  I guess if you had a 
new-style except: that then used a 3-argument raise, you could end up with 
that.  I'm not sure if that's really a problem though.

In 2.6, we'll still be using the old exception machinery, so the raise will 
"do the right thing", it's just that the exception instance will have a 
redundant __traceback__.

I guess, if anything, my inclination would be to have the three-argument 
"raise" delete e.__traceback__.  T2 will get put on it if it's caught by a 
new-style except: clause.

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