JezK
Edit File: traceback.py
"""Extract, format and print information about Python stack traces.""" import linecache import sys import types __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', 'tb_lineno'] def _print(file, str='', terminator='\n'): file.write(str+terminator) 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()) def format_list(extracted_list): """Format a list of traceback entry tuples for printing. Given a list of tuples as returned by extract_tb() or extract_stack(), return a list of strings ready for printing. Each string in the resulting list corresponds to the item with the same index in the argument list. Each string ends in a newline; 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 def print_tb(tb, limit=None, file=None): """Print up to 'limit' stack trace entries from the traceback 'tb'. If 'limit' is omitted or None, all entries are printed. If 'file' is omitted or None, the output goes to sys.stderr; otherwise '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 def format_tb(tb, limit = None): """A shorthand for 'format_list(extract_stack(f, limit)).""" return format_list(extract_tb(tb, limit)) def extract_tb(tb, limit = None): """Return list of up to limit pre-processed entries from traceback. This is useful for alternate formatting of stack traces. If 'limit' is omitted or None, all entries are extracted. A pre-processed stack trace entry is a quadruple (filename, line number, function name, text) representing the information that is usually printed for a stack trace. The text is a string with 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 def print_exception(etype, value, tb, limit=None, file=None): """Print exception up to 'limit' stack trace entries from 'tb' to 'file'. This differs from print_tb() in the following ways: (1) if traceback is not None, it prints a header "Traceback (most recent call last):"; (2) it prints the exception type and value after the stack trace; (3) if type is SyntaxError and value has the appropriate format, it prints the line where the syntax error occurred with a caret on the next line indicating the approximate position of the error. """ 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: _print(file, line, '') def format_exception(etype, value, tb, limit = None): """Format a stack trace and the exception information. The arguments have the same meaning as the corresponding arguments to print_exception(). The return value is a list of strings, each ending in a newline and some containing internal newlines. When 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) else: list = [] list = list + format_exception_only(etype, value) return list def format_exception_only(etype, value): """Format the exception part of a traceback. The arguments are the exception type and value such as given by sys.last_type and sys.last_value. The return value is a list of strings, each ending in a newline. Normally, the list contains a single string; however, for SyntaxError exceptions, it contains several lines that (when printed) display detailed information about where the syntax error occurred. The message indicating which exception occurred is always the last string in the list. """ # An instance should not have a meaningful value parameter, but # sometimes does, particularly for string exceptions, such as # >>> raise string1, string2 # deprecated # # Clear these out first because issubtype(string1, SyntaxError) # would raise another exception and mask the original problem. if (isinstance(etype, BaseException) or isinstance(etype, types.InstanceType) or etype is None or type(etype) is str): return [_format_final_exc_line(etype, value)] stype = etype.__name__ if not issubclass(etype, SyntaxError): return [_format_final_exc_line(stype, value)] # It was a syntax error; show exactly where the problem was found. lines = [] try: msg, (filename, lineno, offset, badline) = value.args except Exception: pass else: filename = filename or "<string>" lines.append(' File "%s", line %d\n' % (filename, lineno)) if badline is not None: lines.append(' %s\n' % 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)) value = msg lines.append(_format_final_exc_line(stype, value)) return lines def _format_final_exc_line(etype, value): """Return a list of a single line -- normal case for format_exception_only""" valuestr = _some_str(value) if value is None or not valuestr: line = "%s\n" % etype else: line = "%s: %s\n" % (etype, valuestr) return line def _some_str(value): try: return str(value) except Exception: pass try: value = unicode(value) return value.encode("ascii", "backslashreplace") except Exception: pass return '<unprintable %s object>' % type(value).__name__ def print_exc(limit=None, file=None): """Shorthand for 'print_exception(sys.exc_type, sys.exc_value, sys.exc_traceback, limit, file)'. (In fact, it uses sys.exc_info() to retrieve the same information in a thread-safe way.)""" if file is None: file = sys.stderr try: etype, value, tb = sys.exc_info() print_exception(etype, value, tb, limit, file) finally: etype = value = tb = None def format_exc(limit=None): """Like print_exc() but return a string.""" try: etype, value, tb = sys.exc_info() return ''.join(format_exception(etype, value, tb, limit)) finally: etype = value = tb = None def print_last(limit=None, file=None): """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) def print_stack(f=None, limit=None, file=None): """Print a stack trace from its invocation point. The optional 'f' argument can be used to specify an alternate 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) 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)) def extract_stack(f=None, limit = None): """Extract the raw traceback from the current stack frame. The return value has the same format as for extract_tb(). The optional 'f' and 'limit' arguments have the same meaning as for print_stack(). Each item in the list is a quadruple (filename, 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 def tb_lineno(tb): """Calculate correct line number of traceback given in tb. Obsolete in 2.3. """ return tb.tb_lineno