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implement chained exception tracebacks

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patch from Antoine Pitrou #3112
This commit is contained in:
Benjamin Peterson 2008-07-15 15:32:09 +00:00
parent 9bab65c259
commit e65282114e
10 changed files with 449 additions and 133 deletions
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82
Lib/traceback.py
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@ -3,6 +3,7 @@
import linecache
import sys
import types
import itertools
__all__ = ['extract_stack', 'extract_tb', 'format_exception',
'format_exception_only', 'format_list', 'format_stack',
@ -107,7 +108,32 @@ def extract_tb(tb, limit = None):
return list
def print_exception(etype, value, tb, limit=None, file=None):
_cause_message = (
"\nThe above exception was the direct cause "
"of the following exception:\n")
_context_message = (
"\nDuring handling of the above exception, "
"another exception occurred:\n")
def _iter_chain(exc, custom_tb=None, seen=None):
if seen is None:
seen = set()
seen.add(exc)
its = []
cause = exc.__cause__
context = exc.__context__
if cause is not None and cause not in seen:
its.append(_iter_chain(cause, None, seen))
its.append([(_cause_message, None)])
if context is not None and context is not cause and context not in seen:
its.append(_iter_chain(context, None, seen))
its.append([(_context_message, None)])
its.append([(exc, custom_tb or exc.__traceback__)])
return itertools.chain(*its)
def print_exception(etype, value, tb, limit=None, file=None, chain=True):
"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
This differs from print_tb() in the following ways: (1) if
@ -120,15 +146,23 @@ def print_exception(etype, value, tb, limit=None, file=None):
"""
if file is None:
file = sys.stderr
if tb:
_print(file, 'Traceback (most recent call last):')
print_tb(tb, limit, file)
lines = format_exception_only(etype, value)
for line in lines[:-1]:
_print(file, line, ' ')
_print(file, lines[-1], '')
if chain:
values = _iter_chain(value, tb)
else:
values = [(value, tb)]
for value, tb in values:
if isinstance(value, str):
_print(file, value)
continue
if tb:
_print(file, 'Traceback (most recent call last):')
print_tb(tb, limit, file)
lines = format_exception_only(type(value), value)
for line in lines[:-1]:
_print(file, line, ' ')
_print(file, lines[-1], '')
def format_exception(etype, value, tb, limit = None):
def format_exception(etype, value, tb, limit=None, chain=True):
"""Format a stack trace and the exception information.
The arguments have the same meaning as the corresponding arguments
@ -137,12 +171,19 @@ def format_exception(etype, value, tb, limit = None):
these lines are concatenated and printed, exactly the same text is
printed as does print_exception().
"""
if tb:
list = ['Traceback (most recent call last):\n']
list = list + format_tb(tb, limit)
list = []
if chain:
values = _iter_chain(value, tb)
else:
list = []
list = list + format_exception_only(etype, value)
values = [(value, tb)]
for value, tb in values:
if isinstance(value, str):
list.append(value + '\n')
continue
if tb:
list.append('Traceback (most recent call last):\n')
list.extend(format_tb(tb, limit))
list.extend(format_exception_only(type(value), value))
return list
def format_exception_only(etype, value):
@ -208,33 +249,34 @@ def _some_str(value):
return '<unprintable %s object>' % type(value).__name__
def print_exc(limit=None, file=None):
def print_exc(limit=None, file=None, chain=True):
"""Shorthand for 'print_exception(*sys.exc_info(), limit, file)'."""
if file is None:
file = sys.stderr
try:
etype, value, tb = sys.exc_info()
print_exception(etype, value, tb, limit, file)
print_exception(etype, value, tb, limit, file, chain)
finally:
etype = value = tb = None
def format_exc(limit=None):
def format_exc(limit=None, chain=True):
"""Like print_exc() but return a string."""
try:
etype, value, tb = sys.exc_info()
return ''.join(format_exception(etype, value, tb, limit))
return ''.join(
format_exception(etype, value, tb, limit, chain))
finally:
etype = value = tb = None
def print_last(limit=None, file=None):
def print_last(limit=None, file=None, chain=True):
"""This is a shorthand for 'print_exception(sys.last_type,
sys.last_value, sys.last_traceback, limit, file)'."""
if file is None:
file = sys.stderr
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
limit, file)
limit, file, chain)
def print_stack(f=None, limit=None, file=None):