refactor traceback.py to reduce code duplication (closes #17646)
Patch by Martin Morrison.
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 33b86c7..3aa1578 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -2,26 +2,31 @@
import linecache
import sys
+import operator
__all__ = ['extract_stack', 'extract_tb', 'format_exception',
'format_exception_only', 'format_list', 'format_stack',
'format_tb', 'print_exc', 'format_exc', 'print_exception',
'print_last', 'print_stack', 'print_tb']
-def _print(file, str='', terminator='\n'):
- file.write(str+terminator)
+#
+# Formatting and printing lists of traceback lines.
+#
+def _format_list_iter(extracted_list):
+ for filename, lineno, name, line in extracted_list:
+ item = ' File "{}", line {}, in {}\n'.format(filename, lineno, name)
+ if line:
+ item = item + ' {}\n'.format(line.strip())
+ yield item
def print_list(extracted_list, file=None):
"""Print the list of tuples as returned by extract_tb() or
extract_stack() as a formatted stack trace to the given file."""
if file is None:
file = sys.stderr
- for filename, lineno, name, line in extracted_list:
- _print(file,
- ' File "%s", line %d, in %s' % (filename,lineno,name))
- if line:
- _print(file, ' %s' % line.strip())
+ for item in _format_list_iter(extracted_list):
+ print(item, file=file, end="")
def format_list(extracted_list):
"""Format a list of traceback entry tuples for printing.
@@ -33,14 +38,44 @@
the strings may contain internal newlines as well, for those items
whose source text line is not None.
"""
- list = []
- for filename, lineno, name, line in extracted_list:
- item = ' File "%s", line %d, in %s\n' % (filename,lineno,name)
- if line:
- item = item + ' %s\n' % line.strip()
- list.append(item)
- return list
+ return list(_format_list_iter(extracted_list))
+#
+# Printing and Extracting Tracebacks.
+#
+
+# extractor takes curr and needs to return a tuple of:
+# - Frame object
+# - Line number
+# - Next item (same type as curr)
+# In practice, curr is either a traceback or a frame.
+def _extract_tb_or_stack_iter(curr, limit, extractor):
+ if limit is None:
+ limit = getattr(sys, 'tracebacklimit', None)
+
+ n = 0
+ while curr is not None and (limit is None or n < limit):
+ f, lineno, next_item = extractor(curr)
+ co = f.f_code
+ filename = co.co_filename
+ name = co.co_name
+
+ linecache.checkcache(filename)
+ line = linecache.getline(filename, lineno, f.f_globals)
+
+ if line:
+ line = line.strip()
+ else:
+ line = None
+
+ yield (filename, lineno, name, line)
+ curr = next_item
+ n += 1
+
+def _extract_tb_iter(tb, limit):
+ return _extract_tb_or_stack_iter(
+ tb, limit,
+ operator.attrgetter("tb_frame", "tb_lineno", "tb_next"))
def print_tb(tb, limit=None, file=None):
"""Print up to 'limit' stack trace entries from the traceback 'tb'.
@@ -50,29 +85,11 @@
'file' should be an open file or file-like object with a write()
method.
"""
- if file is None:
- file = sys.stderr
- if limit is None:
- if hasattr(sys, 'tracebacklimit'):
- limit = sys.tracebacklimit
- n = 0
- while tb is not None and (limit is None or n < limit):
- f = tb.tb_frame
- lineno = tb.tb_lineno
- co = f.f_code
- filename = co.co_filename
- name = co.co_name
- _print(file,
- ' File "%s", line %d, in %s' % (filename, lineno, name))
- linecache.checkcache(filename)
- line = linecache.getline(filename, lineno, f.f_globals)
- if line: _print(file, ' ' + line.strip())
- tb = tb.tb_next
- n = n+1
+ print_list(extract_tb(tb, limit=limit), file=file)
def format_tb(tb, limit=None):
- """A shorthand for 'format_list(extract_stack(f, limit))."""
- return format_list(extract_tb(tb, limit))
+ """A shorthand for 'format_list(extract_tb(tb, limit))."""
+ return format_list(extract_tb(tb, limit=limit))
def extract_tb(tb, limit=None):
"""Return list of up to limit pre-processed entries from traceback.
@@ -85,26 +102,11 @@
leading and trailing whitespace stripped; if the source is not
available it is None.
"""
- if limit is None:
- if hasattr(sys, 'tracebacklimit'):
- limit = sys.tracebacklimit
- list = []
- n = 0
- while tb is not None and (limit is None or n < limit):
- f = tb.tb_frame
- lineno = tb.tb_lineno
- co = f.f_code
- filename = co.co_filename
- name = co.co_name
- linecache.checkcache(filename)
- line = linecache.getline(filename, lineno, f.f_globals)
- if line: line = line.strip()
- else: line = None
- list.append((filename, lineno, name, line))
- tb = tb.tb_next
- n = n+1
- return list
+ return list(_extract_tb_iter(tb, limit=limit))
+#
+# Exception formatting and output.
+#
_cause_message = (
"\nThe above exception was the direct cause "
@@ -134,6 +136,21 @@
for it in its:
yield from it
+def _format_exception_iter(etype, value, tb, limit, chain):
+ if chain:
+ values = _iter_chain(value, tb)
+ else:
+ values = [(value, tb)]
+
+ for value, tb in values:
+ if isinstance(value, str):
+ # This is a cause/context message line
+ yield value + '\n'
+ continue
+ if tb:
+ yield 'Traceback (most recent call last):\n'
+ yield from _format_list_iter(_extract_tb_iter(tb, limit=limit))
+ yield from _format_exception_only_iter(type(value), value)
def print_exception(etype, value, tb, limit=None, file=None, chain=True):
"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
@@ -148,20 +165,8 @@
"""
if file is None:
file = sys.stderr
- 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:
- _print(file, line, '')
+ for line in _format_exception_iter(etype, value, tb, limit, chain):
+ print(line, file=file, end="")
def format_exception(etype, value, tb, limit=None, chain=True):
"""Format a stack trace and the exception information.
@@ -172,20 +177,7 @@
these lines are concatenated and printed, exactly the same text is
printed as does print_exception().
"""
- list = []
- if chain:
- values = _iter_chain(value, tb)
- else:
- 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
+ return list(_format_exception_iter(etype, value, tb, limit, chain))
def format_exception_only(etype, value):
"""Format the exception part of a traceback.
@@ -203,10 +195,14 @@
string in the list.
"""
+ return list(_format_exception_only_iter(etype, value))
+
+def _format_exception_only_iter(etype, value):
# Gracefully handle (the way Python 2.4 and earlier did) the case of
# being called with (None, None).
if etype is None:
- return [_format_final_exc_line(etype, value)]
+ yield _format_final_exc_line(etype, value)
+ return
stype = etype.__name__
smod = etype.__module__
@@ -214,26 +210,26 @@
stype = smod + '.' + stype
if not issubclass(etype, SyntaxError):
- return [_format_final_exc_line(stype, value)]
+ yield _format_final_exc_line(stype, value)
+ return
# It was a syntax error; show exactly where the problem was found.
- lines = []
filename = value.filename or "<string>"
lineno = str(value.lineno) or '?'
- lines.append(' File "%s", line %s\n' % (filename, lineno))
+ yield ' File "{}", line {}\n'.format(filename, lineno)
+
badline = value.text
offset = value.offset
if badline is not None:
- lines.append(' %s\n' % badline.strip())
+ yield ' {}\n'.format(badline.strip())
if offset is not None:
caretspace = badline.rstrip('\n')[:offset].lstrip()
# non-space whitespace (likes tabs) must be kept for alignment
caretspace = ((c.isspace() and c or ' ') for c in caretspace)
# only three spaces to account for offset1 == pos 0
- lines.append(' %s^\n' % ''.join(caretspace))
+ yield ' {}^\n'.format(''.join(caretspace))
msg = value.msg or "<no detail available>"
- lines.append("%s: %s\n" % (stype, msg))
- return lines
+ yield "{}: {}\n".format(stype, msg)
def _format_final_exc_line(etype, value):
valuestr = _some_str(value)
@@ -249,38 +245,34 @@
except:
return '<unprintable %s object>' % type(value).__name__
-
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, chain)
- finally:
- etype = value = tb = None
-
+ print_exception(*sys.exc_info(), limit=limit, file=file, chain=chain)
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, chain))
- finally:
- etype = value = tb = None
-
+ return "".join(format_exception(*sys.exc_info(), limit=limit, chain=chain))
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 not hasattr(sys, "last_type"):
raise ValueError("no last exception")
- if file is None:
- file = sys.stderr
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
limit, file, chain)
+#
+# Printing and Extracting Stacks.
+#
+
+def _extract_stack_iter(f, limit=None):
+ return _extract_tb_or_stack_iter(
+ f, limit, lambda f: (f, f.f_lineno, f.f_back))
+
+def _get_stack(f):
+ if f is None:
+ f = sys._getframe().f_back.f_back
+ return f
def print_stack(f=None, limit=None, file=None):
"""Print a stack trace from its invocation point.
@@ -289,21 +281,11 @@
stack frame at which to start. The optional 'limit' and 'file'
arguments have the same meaning as for print_exception().
"""
- if f is None:
- try:
- raise ZeroDivisionError
- except ZeroDivisionError:
- f = sys.exc_info()[2].tb_frame.f_back
- print_list(extract_stack(f, limit), file)
+ print_list(extract_stack(_get_stack(f), limit=limit), file=file)
def format_stack(f=None, limit=None):
"""Shorthand for 'format_list(extract_stack(f, limit))'."""
- if f is None:
- try:
- raise ZeroDivisionError
- except ZeroDivisionError:
- f = sys.exc_info()[2].tb_frame.f_back
- return format_list(extract_stack(f, limit))
+ return format_list(extract_stack(_get_stack(f), limit=limit))
def extract_stack(f=None, limit=None):
"""Extract the raw traceback from the current stack frame.
@@ -314,27 +296,6 @@
line number, function name, text), and the entries are in order
from oldest to newest stack frame.
"""
- if f is None:
- try:
- raise ZeroDivisionError
- except ZeroDivisionError:
- f = sys.exc_info()[2].tb_frame.f_back
- if limit is None:
- if hasattr(sys, 'tracebacklimit'):
- limit = sys.tracebacklimit
- list = []
- n = 0
- while f is not None and (limit is None or n < limit):
- lineno = f.f_lineno
- co = f.f_code
- filename = co.co_filename
- name = co.co_name
- linecache.checkcache(filename)
- line = linecache.getline(filename, lineno, f.f_globals)
- if line: line = line.strip()
- else: line = None
- list.append((filename, lineno, name, line))
- f = f.f_back
- n = n+1
- list.reverse()
- return list
+ stack = list(_extract_stack_iter(_get_stack(f), limit=limit))
+ stack.reverse()
+ return stack