Nick Coghlan wrote:
> With PEP 344, this could simply be:
>
> try:
> parser.parseFile(file)
> exeption Exception, exception:
> raise type(exception)("Error at line %s in file %s" % (x,y))
>
> Introspectively,
> Nick.
>
It doesn't work (unless I misundertand you). For example, the
exceptions.UnicodeTranslateError constructor needs 4 arguments, not 1.
That's the reason why I think a parallel mechanism is necessary to add
additional information when it is necessary to keep the same exception type.
I probably didn't explain myself well too. Suppose this very hacky
implementation working with the statu quo:
class ExceptionStr:
def __init__(self, content):
self.content = content
self.infos = []
def addinfo(self, info):
self.infos.insert(0, info)
def __call__(self):
return '\n'.join(self.infos + [self.content])
import sys
def reraise(exception, info=None):
strFunc = getattr(exception, "__str__", None)
if not isinstance(strFunc, ExceptionStr):
strFunc = ExceptionStr(str(exception))
exception.__str__ = strFunc
if info:
strFunc.addinfo(info)
raise exception, None, sys.exc_info()[-1]
The following code:
try:
try:
raise Exception("hello")
except Exception, exception:
reraise(exception, "doing x")
except Exception, exception:
reraise(exception, "doing y")
would produce something like:
Traceback (most recent call last):
File "somefile.py", line 7, in ?
reraise(exception, "doing y")
File "somefile.py", line 5, in ?
reraise(exception, "doing x")
File "somefile..py", line 3, in ?
raise Exception("hello")
Exception: doing y
doing x
hello
(Note that having the lines 5 and 7 in the traceback is not wanted)
What I propose is to instead have something like:
try:
try:
raise Exception("hello")
except Exception, exception:
# have some way to reraise a copy of "exception"
# or the same exception with additional info "doing x"
# For example:
exception.addinfo("doing x")
raise exception from exception.__context__
except Exception, exception:
# Idem with "doing y"
And have as output:
Traceback (most recent call last):
File "somefile..py", line 3, in ?
raise Exception("hello")
Additional info:
doing y
doing x
Exception: hello
Regards,
Nicolas
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