Stop at exception in my, not library code

Question

I\'m developing an app using a Python library urllib and it is sometimes rising exceptions due to not being able to access an URL.

However, the exception is

Answer 1

I would go with modifying the code:

try:
    resp = urllib.request.urlopen(req)

except Exception as e:
    raise RuntimeError(e)

That way:

• %pdb moves you to your code,
• the original exception is preserved as argument of the "secondary" exception.

You may also monkeypatch urllib.request.urlopen() function:

class MonkeyPatchUrllib(object):
    def __enter__(self):
        self.__urlopen = urllib.request.urlopen
        urllib.request.urlopen = self
    def __exit__(self, exception_type, exception_value, traceback):
        urllib.request.urlopen = self.__urlopen
    def __call__(self, *args, **kwargs):
        try:                                  
            return self.__urlopen(*args, **kwargs)
        except Exception as e:
            raise RuntimeError(e)

Any time you have an exception raised in urlibopen() call within the context manager scope:

with MonkeyPatchUrllib():
    #your code here

%pdb will move you only 1 level away from your code.

[EDIT]

With sys.exc_info() it is possible to preserve a more verbose context of the original exception (like its traceback).