Is there a pattern for propagating details of both errors and warnings?

Question

Is there a common pattern for propagating details of both errors and warnings? By errors I mean serious problems that should cause the flow of code to stop. By warnings I mean issues that merit informing the user of a problem, but are too trivial to stop program flow.

I currently use exceptions to deal with hard errors, and the Python logging framework to record warnings. But now I want to record warnings in a database field of the record currently being processed instead. I guess, I want the warnings to bubble up in the same manner as exceptions, but without stopping program flow.

>>> import logging
>>>
>>> def process_item(item):
...     if item:
...         if item == 'broken':
...             logging.warning('soft error, continue with next item')

...     else:
...         raise Exception('hard error, cannot continue')
...
>>> process_item('good')
>>> process_item(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 6, in process_item
Exception: hard error, cannot continue
>>> process_item('broken')
WARNING:root:soft error, continue with next item

This example (and my current problem) is in Python, but it should apply to other languages with exceptions too.

---

Following David's suggestion and a brief play with the example below, Python's warnings module is the way to go.

import warnings

class MyWarning(Warning):
    pass

def causes_warnings():
    print 'enter causes_warnings'
    warnings.warn("my warning", MyWarning)
    print 'leave causes_warnings'

def do_stuff():
    print 'enter do_stuff'
    causes_warnings()
    causes_warnings()
    causes_warnings()
    print 'leave do_stuff'

with warnings.catch_warnings(record=True) as w:
    # Cause all warnings to always be triggered.
    warnings.simplefilter("always")
    # Trigger a number of warnings.
    do_stuff()
    # Do something (not very) useful with the warnings generated
    print 'Warnings:',','.join([str(warning.message) for warning in w])

Output:

enter do_stuff
enter causes_warnings
leave causes_warnings
enter causes_warnings
leave causes_warnings
enter causes_warnings
leave causes_warnings
leave do_stuff
Warnings: my warning,my warning,my warning

Note: Python 2.6+ is required for catch_warnings.

Answer 1

Look into Python's warnings module, http://docs.python.org/library/warnings.html

I don't think there's much you can say about this problem without specifying the language, as non-terminal error handling varies greatly from one language to another.