[Python-Dev] Idea for avoiding exception masking

[Simon Burton]

On Tue, 28 Jan 2003 19:22:34 -0500
"Raymond Hettinger" <raymond.hettinger@verizon.net> wrote:

> So, here's the bright idea.  Add a function, 
> PyErr_FormatAppend, that leaves the original message
> intact but allows additional information to be added
> (like the name of the called function, identification
> of which argument triggered the error, a clue as
> to how many iterations had passed, or anything else
> that makes the traceback more informative).
> 

There is a difficulty with c functions that implement "overloaded"
behaviour: if the first PyArg_ParseTuple fails, clear the error and
then if the second PyArg_ParseTyple fails (then if ...), that's the error that is
raised.

I came across this problem in the pygtk wrapper. James Henstridge
suggested that the (final) error should be cleared and then raise
an error manually (PyErr_FromString), OK, but this duplicates error information.

What i'd really like to see is something similar to Raymond's suggestion,
allowing a way to raise a disjunction of errors; we don't know which
one is the real error, so raise them all, perhaps inside another "OneOf" error.

Simon Burton.