As others suggested, you could use sys.excepthook:
This function prints out a given traceback and exception to sys.stderr.
When an exception is raised and uncaught, the interpreter calls sys.excepthook with three arguments, the exception class, exception instance, and a traceback object. In an interactive session this happens just before control is returned to the prompt; in a Python program this happens just before the program exits. The handling of such top-level exceptions can be customized by assigning another three-argument function to sys.excepthook.
(emphasis mine)
It's possible to filter a traceback extracted by extract_tb (or similar functions from the traceback module) based on specified directories.
Two functions that can help:
from os.path import join, abspath
from traceback import extract_tb, format_list, format_exception_only
def spotlight(*show):
''' Return a function to be set as new sys.excepthook.
It will SHOW traceback entries for files from these directories. '''
show = tuple(join(abspath(p), '') for p in show)
def _check_file(name):
return name and name.startswith(show)
def _print(type, value, tb):
show = (fs for fs in extract_tb(tb) if _check_file(fs.filename))
fmt = format_list(show) + format_exception_only(type, value)
print(''.join(fmt), end='', file=sys.stderr)
return _print
def shadow(*hide):
''' Return a function to be set as new sys.excepthook.
It will HIDE traceback entries for files from these directories. '''
hide = tuple(join(abspath(p), '') for p in hide)
def _check_file(name):
return name and not name.startswith(hide)
def _print(type, value, tb):
show = (fs for fs in extract_tb(tb) if _check_file(fs.filename))
fmt = format_list(show) + format_exception_only(type, value)
print(''.join(fmt), end='', file=sys.stderr)
return _print
They both use the traceback.extract_tb. It returns "a list of “pre-processed” stack trace entries extracted from the traceback object"; all of them are instances of traceback.FrameSummary (a named tuple). Each traceback.FrameSummary object has a filename field which stores the absolute path of the corresponding file. We check if it starts with any of the directory paths provided as separate function arguments to determine if we'll need to exclude the entry (or keep it).
Here's an Example:
The enum module from the standard library doesn't allow reusing keys,
import enum
enum.Enum('Faulty', 'a a', module=__name__)
yields
Traceback (most recent call last):
File "/home/vaultah/so/shadows/main.py", line 23, in <module>
enum.Enum('Faulty', 'a a', module=__name__)
File "/home/vaultah/cpython/Lib/enum.py", line 243, in __call__
return cls._create_(value, names, module=module, qualname=qualname, type=type, start=start)
File "/home/vaultah/cpython/Lib/enum.py", line 342, in _create_
classdict[member_name] = member_value
File "/home/vaultah/cpython/Lib/enum.py", line 72, in __setitem__
raise TypeError('Attempted to reuse key: %r' % key)
TypeError: Attempted to reuse key: 'a'
We can restrict stack trace entries to our code (in /home/vaultah/so/shadows/main.py).
import sys, enum
sys.excepthook = spotlight('/home/vaultah/so/shadows')
enum.Enum('Faulty', 'a a', module=__name__)
and
import sys, enum
sys.excepthook = shadow('/home/vaultah/cpython/Lib')
enum.Enum('Faulty', 'a a', module=__name__)
give the same result:
File "/home/vaultah/so/shadows/main.py", line 22, in <module>
enum.Enum('Faulty', 'a a', module=__name__)
TypeError: Attempted to reuse key: 'a'
There's a way to exclude all site directories (where 3rd party packages are installed - see site.getsitepackages)
import sys, site, jinja2
sys.excepthook = shadow(*site.getsitepackages())
jinja2.Template('{%}')
# jinja2.exceptions.TemplateSyntaxError: unexpected '}'
# Generates ~30 lines, but will only display 4
Note: Don't forget to restore sys.excepthook from sys.__excepthook__. Unfortunately, you won't be able to "patch-restore" it using a context manager.
