320 lines
11 KiB
Python
320 lines
11 KiB
Python
"""Extract, format and print information about Python stack traces."""
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import linecache
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import sys
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import types
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__all__ = ['extract_stack', 'extract_tb', 'format_exception',
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'format_exception_only', 'format_list', 'format_stack',
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'format_tb', 'print_exc', 'format_exc', 'print_exception',
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'print_last', 'print_stack', 'print_tb', 'tb_lineno']
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def _print(file, str='', terminator='\n'):
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file.write(str+terminator)
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def print_list(extracted_list, file=None):
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"""Print the list of tuples as returned by extract_tb() or
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extract_stack() as a formatted stack trace to the given file."""
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if file is None:
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file = sys.stderr
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for filename, lineno, name, line in extracted_list:
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_print(file,
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' File "%s", line %d, in %s' % (filename,lineno,name))
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if line:
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_print(file, ' %s' % line.strip())
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def format_list(extracted_list):
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"""Format a list of traceback entry tuples for printing.
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Given a list of tuples as returned by extract_tb() or
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extract_stack(), return a list of strings ready for printing.
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Each string in the resulting list corresponds to the item with the
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same index in the argument list. Each string ends in a newline;
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the strings may contain internal newlines as well, for those items
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whose source text line is not None.
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"""
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list = []
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for filename, lineno, name, line in extracted_list:
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item = ' File "%s", line %d, in %s\n' % (filename,lineno,name)
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if line:
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item = item + ' %s\n' % line.strip()
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list.append(item)
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return list
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def print_tb(tb, limit=None, file=None):
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"""Print up to 'limit' stack trace entries from the traceback 'tb'.
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If 'limit' is omitted or None, all entries are printed. If 'file'
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is omitted or None, the output goes to sys.stderr; otherwise
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'file' should be an open file or file-like object with a write()
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method.
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"""
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if file is None:
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file = sys.stderr
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if limit is None:
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if hasattr(sys, 'tracebacklimit'):
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limit = sys.tracebacklimit
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n = 0
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while tb is not None and (limit is None or n < limit):
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f = tb.tb_frame
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lineno = tb.tb_lineno
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co = f.f_code
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filename = co.co_filename
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name = co.co_name
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_print(file,
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' File "%s", line %d, in %s' % (filename, lineno, name))
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linecache.checkcache(filename)
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line = linecache.getline(filename, lineno, f.f_globals)
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if line: _print(file, ' ' + line.strip())
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tb = tb.tb_next
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n = n+1
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def format_tb(tb, limit = None):
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"""A shorthand for 'format_list(extract_tb(tb, limit))'."""
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return format_list(extract_tb(tb, limit))
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def extract_tb(tb, limit = None):
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"""Return list of up to limit pre-processed entries from traceback.
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This is useful for alternate formatting of stack traces. If
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'limit' is omitted or None, all entries are extracted. A
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pre-processed stack trace entry is a quadruple (filename, line
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number, function name, text) representing the information that is
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usually printed for a stack trace. The text is a string with
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leading and trailing whitespace stripped; if the source is not
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available it is None.
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"""
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if limit is None:
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if hasattr(sys, 'tracebacklimit'):
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limit = sys.tracebacklimit
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list = []
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n = 0
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while tb is not None and (limit is None or n < limit):
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f = tb.tb_frame
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lineno = tb.tb_lineno
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co = f.f_code
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filename = co.co_filename
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name = co.co_name
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linecache.checkcache(filename)
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line = linecache.getline(filename, lineno, f.f_globals)
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if line: line = line.strip()
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else: line = None
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list.append((filename, lineno, name, line))
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tb = tb.tb_next
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n = n+1
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return list
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def print_exception(etype, value, tb, limit=None, file=None):
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"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
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This differs from print_tb() in the following ways: (1) if
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traceback is not None, it prints a header "Traceback (most recent
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call last):"; (2) it prints the exception type and value after the
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stack trace; (3) if type is SyntaxError and value has the
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appropriate format, it prints the line where the syntax error
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occurred with a caret on the next line indicating the approximate
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position of the error.
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"""
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if file is None:
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file = sys.stderr
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if tb:
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_print(file, 'Traceback (most recent call last):')
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print_tb(tb, limit, file)
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lines = format_exception_only(etype, value)
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for line in lines:
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_print(file, line, '')
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def format_exception(etype, value, tb, limit = None):
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"""Format a stack trace and the exception information.
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The arguments have the same meaning as the corresponding arguments
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to print_exception(). The return value is a list of strings, each
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ending in a newline and some containing internal newlines. When
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these lines are concatenated and printed, exactly the same text is
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printed as does print_exception().
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"""
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if tb:
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list = ['Traceback (most recent call last):\n']
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list = list + format_tb(tb, limit)
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else:
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list = []
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list = list + format_exception_only(etype, value)
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return list
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def format_exception_only(etype, value):
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"""Format the exception part of a traceback.
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The arguments are the exception type and value such as given by
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sys.last_type and sys.last_value. The return value is a list of
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strings, each ending in a newline.
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Normally, the list contains a single string; however, for
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SyntaxError exceptions, it contains several lines that (when
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printed) display detailed information about where the syntax
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error occurred.
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The message indicating which exception occurred is always the last
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string in the list.
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"""
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# An instance should not have a meaningful value parameter, but
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# sometimes does, particularly for string exceptions, such as
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# >>> raise string1, string2 # deprecated
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#
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# Clear these out first because issubtype(string1, SyntaxError)
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# would raise another exception and mask the original problem.
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if (isinstance(etype, BaseException) or
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isinstance(etype, types.InstanceType) or
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etype is None or type(etype) is str):
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return [_format_final_exc_line(etype, value)]
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stype = etype.__name__
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if not issubclass(etype, SyntaxError):
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return [_format_final_exc_line(stype, value)]
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# It was a syntax error; show exactly where the problem was found.
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lines = []
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try:
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msg, (filename, lineno, offset, badline) = value.args
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except Exception:
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pass
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else:
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filename = filename or "<string>"
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lines.append(' File "%s", line %d\n' % (filename, lineno))
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if badline is not None:
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lines.append(' %s\n' % badline.strip())
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if offset is not None:
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caretspace = badline.rstrip('\n')[:offset].lstrip()
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# non-space whitespace (likes tabs) must be kept for alignment
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caretspace = ((c.isspace() and c or ' ') for c in caretspace)
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# only three spaces to account for offset1 == pos 0
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lines.append(' %s^\n' % ''.join(caretspace))
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value = msg
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lines.append(_format_final_exc_line(stype, value))
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return lines
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def _format_final_exc_line(etype, value):
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"""Return a list of a single line -- normal case for format_exception_only"""
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valuestr = _some_str(value)
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if value is None or not valuestr:
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line = "%s\n" % etype
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else:
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line = "%s: %s\n" % (etype, valuestr)
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return line
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def _some_str(value):
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try:
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return str(value)
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except Exception:
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pass
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try:
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value = unicode(value)
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return value.encode("ascii", "backslashreplace")
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except Exception:
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pass
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return '<unprintable %s object>' % type(value).__name__
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def print_exc(limit=None, file=None):
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"""Shorthand for 'print_exception(sys.exc_type, sys.exc_value, sys.exc_traceback, limit, file)'.
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(In fact, it uses sys.exc_info() to retrieve the same information
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in a thread-safe way.)"""
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if file is None:
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file = sys.stderr
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try:
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etype, value, tb = sys.exc_info()
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print_exception(etype, value, tb, limit, file)
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finally:
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etype = value = tb = None
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def format_exc(limit=None):
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"""Like print_exc() but return a string."""
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try:
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etype, value, tb = sys.exc_info()
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return ''.join(format_exception(etype, value, tb, limit))
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finally:
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etype = value = tb = None
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def print_last(limit=None, file=None):
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"""This is a shorthand for 'print_exception(sys.last_type,
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sys.last_value, sys.last_traceback, limit, file)'."""
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if not hasattr(sys, "last_type"):
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raise ValueError("no last exception")
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if file is None:
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file = sys.stderr
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print_exception(sys.last_type, sys.last_value, sys.last_traceback,
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limit, file)
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def print_stack(f=None, limit=None, file=None):
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"""Print a stack trace from its invocation point.
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The optional 'f' argument can be used to specify an alternate
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stack frame at which to start. The optional 'limit' and 'file'
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arguments have the same meaning as for print_exception().
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"""
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if f is None:
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try:
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raise ZeroDivisionError
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except ZeroDivisionError:
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f = sys.exc_info()[2].tb_frame.f_back
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print_list(extract_stack(f, limit), file)
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def format_stack(f=None, limit=None):
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"""Shorthand for 'format_list(extract_stack(f, limit))'."""
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if f is None:
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try:
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raise ZeroDivisionError
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except ZeroDivisionError:
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f = sys.exc_info()[2].tb_frame.f_back
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return format_list(extract_stack(f, limit))
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def extract_stack(f=None, limit = None):
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"""Extract the raw traceback from the current stack frame.
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The return value has the same format as for extract_tb(). The
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optional 'f' and 'limit' arguments have the same meaning as for
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print_stack(). Each item in the list is a quadruple (filename,
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line number, function name, text), and the entries are in order
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from oldest to newest stack frame.
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"""
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if f is None:
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try:
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raise ZeroDivisionError
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except ZeroDivisionError:
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f = sys.exc_info()[2].tb_frame.f_back
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if limit is None:
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if hasattr(sys, 'tracebacklimit'):
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limit = sys.tracebacklimit
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list = []
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n = 0
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while f is not None and (limit is None or n < limit):
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lineno = f.f_lineno
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co = f.f_code
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filename = co.co_filename
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name = co.co_name
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linecache.checkcache(filename)
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line = linecache.getline(filename, lineno, f.f_globals)
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if line: line = line.strip()
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else: line = None
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list.append((filename, lineno, name, line))
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f = f.f_back
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n = n+1
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list.reverse()
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return list
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def tb_lineno(tb):
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"""Calculate correct line number of traceback given in tb.
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Obsolete in 2.3.
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"""
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return tb.tb_lineno
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