Python per-module excepthooks

example_usage.py

from .hook import register_module_excepthook
from .hook import install_global_excepthook


def some_module_function_that_may_fail():
    raise ValueError("whoops!")
    

def module_excepthook(type_, value, tb):
    print("Gosh, " + __name__ + " has produced an error!")
    print(tb)

    
register_module_excepthook(__name__, module_excepthook)

# This must be called once somewhere in the application.
install_global_excepthook()

hook.py

"""
sys.excepthook is global, meaning we can only define one at any given time.

Using the functions below we can make the global excepthook handle errors
differently based on the module filepath they came from, effectively giving 
us per-module excepthooks.

"""
import os
import re
import sys
import traceback
from StringIO import StringIO


tb_file_regex = r'\"(?P<file>.+)\.py[cod]{0,1}\"'
file_regex = r'(?P<file>.+)\.py[cod]{0,1}'

_excepthook_registry = {}


def install_global_excepthook():
    sys.excepthook = _excepthook
    
    
def register_module_excepthook(module_name, func):
    module = sys.modules[module_name]
    module_file = os.path.abspath(module.__file__)
    relevant_filename = re.match(file_regex, module_file).group("file")
    _excepthook_registry[relevant_filename] = func


def _excepthook(type_, value, tb):
    """Assign this to sys.excepthook to handle per-module-hooks."""
    buf = StringIO()
    traceback.print_tb(tb, file=buf)
    matches = re.findall(tb_file_regex, buf.getvalue())
    if not matches:
        return
    culprit_filepath = matches[-1]
    culprit_relevant_filename, _ = os.path.splitext(culprit_filepath)
    hook = _excepthook_registry.get(culprit_relevant_filename)
    if hook:
        hook(type_, value, tb)