[newbie] Confused with raise w/o args

[jfj]

Fredrik Lundh wrote:

> "jfj" <jfj at freemail.gr> wrote:
> 
> 
>>Wait! second that. We would like to
> 
> 
> hmm.  are you seconding yourself, and refering to you and yourself as we?
> 

:)
"we" refers to all python users.

> no.  your foo() function raises B, and is called from the exception
> handler in b1.  exception handlers are free to raise new exceptions
> at any time.

Yes but 'B' has been handled while the handler of 'A' has not finished yet.
Here is a better example:
##################
# comment out one of the two
# raise statements to test this
import traceback
def foo():
     raise     # this raises an 'A'
     try:
        raise B
     except:
        pass
     raise     # this raises a 'B'. I find this peculiar

try:
  try:
     raise A
  except:
     foo()
except:
  traceback.print_exc()
##################


It seems that there are no uses of this "feature".
I guess that's the easy way to implement re-raise in CPython.

I quickly grepped through the sources (;)) and it seems that
perhaps it would be possible to introduce a new opcode
JUMP_FORWARD_CLEANUP_EXC which would be used to leave except clauses.
Then, RAISE_VARARGS would push exceptions on to an "exception stack"
and JUMP_FORWARD_CLEANUP_EXC would pop them.
The bottom element in such an exception stack would be the
UnhandledException.  're-raise' would use the stack-top exception.

However, there are no bytecode changes until AST is merged, so this
will have to wait..


jfj