| 1 | """Extract, format and print information about Python stack traces."""
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| 2 |
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| 3 | import linecache
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| 4 | import sys
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| 5 | import types
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| 6 |
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| 7 | __all__ = ['extract_stack', 'extract_tb', 'format_exception',
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| 8 | 'format_exception_only', 'format_list', 'format_stack',
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| 9 | 'format_tb', 'print_exc', 'format_exc', 'print_exception',
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| 10 | 'print_last', 'print_stack', 'print_tb', 'tb_lineno']
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| 11 |
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| 12 | def _print(file, str='', terminator='\n'):
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| 13 | file.write(str+terminator)
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| 14 |
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| 15 |
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| 16 | def print_list(extracted_list, file=None):
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| 17 | """Print the list of tuples as returned by extract_tb() or
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| 18 | extract_stack() as a formatted stack trace to the given file."""
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| 19 | if file is None:
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| 20 | file = sys.stderr
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| 21 | for filename, lineno, name, line in extracted_list:
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| 22 | _print(file,
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| 23 | ' File "%s", line %d, in %s' % (filename,lineno,name))
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| 24 | if line:
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| 25 | _print(file, ' %s' % line.strip())
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| 26 |
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| 27 | def format_list(extracted_list):
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| 28 | """Format a list of traceback entry tuples for printing.
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| 29 |
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| 30 | Given a list of tuples as returned by extract_tb() or
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| 31 | extract_stack(), return a list of strings ready for printing.
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| 32 | Each string in the resulting list corresponds to the item with the
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| 33 | same index in the argument list. Each string ends in a newline;
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| 34 | the strings may contain internal newlines as well, for those items
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| 35 | whose source text line is not None.
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| 36 | """
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| 37 | list = []
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| 38 | for filename, lineno, name, line in extracted_list:
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| 39 | item = ' File "%s", line %d, in %s\n' % (filename,lineno,name)
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| 40 | if line:
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| 41 | item = item + ' %s\n' % line.strip()
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| 42 | list.append(item)
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| 43 | return list
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| 44 |
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| 45 |
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| 46 | def print_tb(tb, limit=None, file=None):
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| 47 | """Print up to 'limit' stack trace entries from the traceback 'tb'.
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| 48 |
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| 49 | If 'limit' is omitted or None, all entries are printed. If 'file'
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| 50 | is omitted or None, the output goes to sys.stderr; otherwise
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| 51 | 'file' should be an open file or file-like object with a write()
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| 52 | method.
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| 53 | """
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| 54 | if file is None:
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| 55 | file = sys.stderr
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| 56 | if limit is None:
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| 57 | if hasattr(sys, 'tracebacklimit'):
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| 58 | limit = sys.tracebacklimit
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| 59 | n = 0
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| 60 | while tb is not None and (limit is None or n < limit):
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| 61 | f = tb.tb_frame
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| 62 | lineno = tb.tb_lineno
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| 63 | co = f.f_code
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| 64 | filename = co.co_filename
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| 65 | name = co.co_name
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| 66 | _print(file,
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| 67 | ' File "%s", line %d, in %s' % (filename, lineno, name))
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| 68 | linecache.checkcache(filename)
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| 69 | line = linecache.getline(filename, lineno, f.f_globals)
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| 70 | if line: _print(file, ' ' + line.strip())
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| 71 | tb = tb.tb_next
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| 72 | n = n+1
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| 73 |
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| 74 | def format_tb(tb, limit = None):
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| 75 | """A shorthand for 'format_list(extract_tb(tb, limit))'."""
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| 76 | return format_list(extract_tb(tb, limit))
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| 77 |
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| 78 | def extract_tb(tb, limit = None):
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| 79 | """Return list of up to limit pre-processed entries from traceback.
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| 80 |
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| 81 | This is useful for alternate formatting of stack traces. If
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| 82 | 'limit' is omitted or None, all entries are extracted. A
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| 83 | pre-processed stack trace entry is a quadruple (filename, line
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| 84 | number, function name, text) representing the information that is
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| 85 | usually printed for a stack trace. The text is a string with
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| 86 | leading and trailing whitespace stripped; if the source is not
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| 87 | available it is None.
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| 88 | """
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| 89 | if limit is None:
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| 90 | if hasattr(sys, 'tracebacklimit'):
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| 91 | limit = sys.tracebacklimit
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| 92 | list = []
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| 93 | n = 0
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| 94 | while tb is not None and (limit is None or n < limit):
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| 95 | f = tb.tb_frame
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| 96 | lineno = tb.tb_lineno
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| 97 | co = f.f_code
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| 98 | filename = co.co_filename
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| 99 | name = co.co_name
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| 100 | linecache.checkcache(filename)
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| 101 | line = linecache.getline(filename, lineno, f.f_globals)
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| 102 | if line: line = line.strip()
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| 103 | else: line = None
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| 104 | list.append((filename, lineno, name, line))
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| 105 | tb = tb.tb_next
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| 106 | n = n+1
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| 107 | return list
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| 108 |
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| 109 |
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| 110 | def print_exception(etype, value, tb, limit=None, file=None):
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| 111 | """Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
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| 112 |
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| 113 | This differs from print_tb() in the following ways: (1) if
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| 114 | traceback is not None, it prints a header "Traceback (most recent
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| 115 | call last):"; (2) it prints the exception type and value after the
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| 116 | stack trace; (3) if type is SyntaxError and value has the
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| 117 | appropriate format, it prints the line where the syntax error
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| 118 | occurred with a caret on the next line indicating the approximate
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| 119 | position of the error.
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| 120 | """
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| 121 | if file is None:
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| 122 | file = sys.stderr
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| 123 | if tb:
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| 124 | _print(file, 'Traceback (most recent call last):')
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| 125 | print_tb(tb, limit, file)
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| 126 | lines = format_exception_only(etype, value)
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| 127 | for line in lines:
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| 128 | _print(file, line, '')
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| 129 |
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| 130 | def format_exception(etype, value, tb, limit = None):
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| 131 | """Format a stack trace and the exception information.
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| 132 |
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| 133 | The arguments have the same meaning as the corresponding arguments
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| 134 | to print_exception(). The return value is a list of strings, each
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| 135 | ending in a newline and some containing internal newlines. When
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| 136 | these lines are concatenated and printed, exactly the same text is
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| 137 | printed as does print_exception().
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| 138 | """
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| 139 | if tb:
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| 140 | list = ['Traceback (most recent call last):\n']
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| 141 | list = list + format_tb(tb, limit)
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| 142 | else:
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| 143 | list = []
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| 144 | list = list + format_exception_only(etype, value)
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| 145 | return list
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| 146 |
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| 147 | def format_exception_only(etype, value):
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| 148 | """Format the exception part of a traceback.
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| 149 |
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| 150 | The arguments are the exception type and value such as given by
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| 151 | sys.last_type and sys.last_value. The return value is a list of
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| 152 | strings, each ending in a newline.
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| 153 |
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| 154 | Normally, the list contains a single string; however, for
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| 155 | SyntaxError exceptions, it contains several lines that (when
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| 156 | printed) display detailed information about where the syntax
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| 157 | error occurred.
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| 158 |
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| 159 | The message indicating which exception occurred is always the last
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| 160 | string in the list.
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| 161 |
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| 162 | """
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| 163 |
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| 164 | # An instance should not have a meaningful value parameter, but
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| 165 | # sometimes does, particularly for string exceptions, such as
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| 166 | # >>> raise string1, string2 # deprecated
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| 167 | #
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| 168 | # Clear these out first because issubtype(string1, SyntaxError)
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| 169 | # would raise another exception and mask the original problem.
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| 170 | if (isinstance(etype, BaseException) or
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| 171 | isinstance(etype, types.InstanceType) or
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| 172 | etype is None or type(etype) is str):
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| 173 | return [_format_final_exc_line(etype, value)]
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| 174 |
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| 175 | stype = etype.__name__
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| 176 |
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| 177 | if not issubclass(etype, SyntaxError):
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| 178 | return [_format_final_exc_line(stype, value)]
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| 179 |
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| 180 | # It was a syntax error; show exactly where the problem was found.
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| 181 | lines = []
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| 182 | try:
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| 183 | msg, (filename, lineno, offset, badline) = value.args
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| 184 | except Exception:
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| 185 | pass
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| 186 | else:
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| 187 | filename = filename or "<string>"
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| 188 | lines.append(' File "%s", line %d\n' % (filename, lineno))
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| 189 | if badline is not None:
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| 190 | lines.append(' %s\n' % badline.strip())
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| 191 | if offset is not None:
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| 192 | caretspace = badline.rstrip('\n')
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| 193 | offset = min(len(caretspace), offset) - 1
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| 194 | caretspace = caretspace[:offset].lstrip()
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| 195 | # non-space whitespace (likes tabs) must be kept for alignment
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| 196 | caretspace = ((c.isspace() and c or ' ') for c in caretspace)
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| 197 | lines.append(' %s^\n' % ''.join(caretspace))
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| 198 | value = msg
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| 199 |
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| 200 | lines.append(_format_final_exc_line(stype, value))
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| 201 | return lines
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| 202 |
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| 203 | def _format_final_exc_line(etype, value):
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| 204 | """Return a list of a single line -- normal case for format_exception_only"""
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| 205 | valuestr = _some_str(value)
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| 206 | if value is None or not valuestr:
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| 207 | line = "%s\n" % etype
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| 208 | else:
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| 209 | line = "%s: %s\n" % (etype, valuestr)
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| 210 | return line
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| 211 |
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| 212 | def _some_str(value):
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| 213 | try:
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| 214 | return str(value)
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| 215 | except Exception:
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| 216 | pass
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| 217 | try:
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| 218 | value = unicode(value)
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| 219 | return value.encode("ascii", "backslashreplace")
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| 220 | except Exception:
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| 221 | pass
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| 222 | return '<unprintable %s object>' % type(value).__name__
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| 223 |
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| 224 |
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| 225 | def print_exc(limit=None, file=None):
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| 226 | """Shorthand for 'print_exception(sys.exc_type, sys.exc_value, sys.exc_traceback, limit, file)'.
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| 227 | (In fact, it uses sys.exc_info() to retrieve the same information
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| 228 | in a thread-safe way.)"""
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| 229 | if file is None:
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| 230 | file = sys.stderr
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| 231 | try:
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| 232 | etype, value, tb = sys.exc_info()
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| 233 | print_exception(etype, value, tb, limit, file)
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| 234 | finally:
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| 235 | etype = value = tb = None
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| 236 |
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| 237 |
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| 238 | def format_exc(limit=None):
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| 239 | """Like print_exc() but return a string."""
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| 240 | try:
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| 241 | etype, value, tb = sys.exc_info()
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| 242 | return ''.join(format_exception(etype, value, tb, limit))
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| 243 | finally:
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| 244 | etype = value = tb = None
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| 245 |
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| 246 |
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| 247 | def print_last(limit=None, file=None):
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| 248 | """This is a shorthand for 'print_exception(sys.last_type,
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| 249 | sys.last_value, sys.last_traceback, limit, file)'."""
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| 250 | if not hasattr(sys, "last_type"):
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| 251 | raise ValueError("no last exception")
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| 252 | if file is None:
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| 253 | file = sys.stderr
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| 254 | print_exception(sys.last_type, sys.last_value, sys.last_traceback,
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| 255 | limit, file)
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| 256 |
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| 257 |
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| 258 | def print_stack(f=None, limit=None, file=None):
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| 259 | """Print a stack trace from its invocation point.
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| 260 |
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| 261 | The optional 'f' argument can be used to specify an alternate
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| 262 | stack frame at which to start. The optional 'limit' and 'file'
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| 263 | arguments have the same meaning as for print_exception().
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| 264 | """
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| 265 | if f is None:
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| 266 | try:
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| 267 | raise ZeroDivisionError
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| 268 | except ZeroDivisionError:
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| 269 | f = sys.exc_info()[2].tb_frame.f_back
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| 270 | print_list(extract_stack(f, limit), file)
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| 271 |
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| 272 | def format_stack(f=None, limit=None):
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| 273 | """Shorthand for 'format_list(extract_stack(f, limit))'."""
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| 274 | if f is None:
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| 275 | try:
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| 276 | raise ZeroDivisionError
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| 277 | except ZeroDivisionError:
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| 278 | f = sys.exc_info()[2].tb_frame.f_back
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| 279 | return format_list(extract_stack(f, limit))
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| 280 |
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| 281 | def extract_stack(f=None, limit = None):
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| 282 | """Extract the raw traceback from the current stack frame.
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| 283 |
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| 284 | The return value has the same format as for extract_tb(). The
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| 285 | optional 'f' and 'limit' arguments have the same meaning as for
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| 286 | print_stack(). Each item in the list is a quadruple (filename,
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| 287 | line number, function name, text), and the entries are in order
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| 288 | from oldest to newest stack frame.
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| 289 | """
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| 290 | if f is None:
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| 291 | try:
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| 292 | raise ZeroDivisionError
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| 293 | except ZeroDivisionError:
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| 294 | f = sys.exc_info()[2].tb_frame.f_back
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| 295 | if limit is None:
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| 296 | if hasattr(sys, 'tracebacklimit'):
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| 297 | limit = sys.tracebacklimit
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| 298 | list = []
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| 299 | n = 0
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| 300 | while f is not None and (limit is None or n < limit):
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| 301 | lineno = f.f_lineno
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| 302 | co = f.f_code
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| 303 | filename = co.co_filename
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| 304 | name = co.co_name
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| 305 | linecache.checkcache(filename)
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| 306 | line = linecache.getline(filename, lineno, f.f_globals)
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| 307 | if line: line = line.strip()
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| 308 | else: line = None
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| 309 | list.append((filename, lineno, name, line))
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| 310 | f = f.f_back
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| 311 | n = n+1
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| 312 | list.reverse()
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| 313 | return list
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| 314 |
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| 315 | def tb_lineno(tb):
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| 316 | """Calculate correct line number of traceback given in tb.
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| 317 |
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| 318 | Obsolete in 2.3.
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| 319 | """
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| 320 | return tb.tb_lineno
|