1 """Extract, format and print information about Python stack traces."""
7 __all__
= ['extract_stack', 'extract_tb', 'format_exception',
8 'format_exception_only', 'format_list', 'format_stack',
9 'format_tb', 'print_exc', 'format_exc', 'print_exception',
10 'print_last', 'print_stack', 'print_tb', 'tb_lineno']
12 def _print(file, str='', terminator
='\n'):
13 file.write(str+terminator
)
16 def print_list(extracted_list
, file=None):
17 """Print the list of tuples as returned by extract_tb() or
18 extract_stack() as a formatted stack trace to the given file."""
21 for filename
, lineno
, name
, line
in extracted_list
:
23 ' File "%s", line %d, in %s' % (filename
,lineno
,name
))
25 _print(file, ' %s' % line
.strip())
27 def format_list(extracted_list
):
28 """Format a list of traceback entry tuples for printing.
30 Given a list of tuples as returned by extract_tb() or
31 extract_stack(), return a list of strings ready for printing.
32 Each string in the resulting list corresponds to the item with the
33 same index in the argument list. Each string ends in a newline;
34 the strings may contain internal newlines as well, for those items
35 whose source text line is not None.
38 for filename
, lineno
, name
, line
in extracted_list
:
39 item
= ' File "%s", line %d, in %s\n' % (filename
,lineno
,name
)
41 item
= item
+ ' %s\n' % line
.strip()
46 def print_tb(tb
, limit
=None, file=None):
47 """Print up to 'limit' stack trace entries from the traceback 'tb'.
49 If 'limit' is omitted or None, all entries are printed. If 'file'
50 is omitted or None, the output goes to sys.stderr; otherwise
51 'file' should be an open file or file-like object with a write()
57 if hasattr(sys
, 'tracebacklimit'):
58 limit
= sys
.tracebacklimit
60 while tb
is not None and (limit
is None or n
< limit
):
64 filename
= co
.co_filename
67 ' File "%s", line %d, in %s' % (filename
,lineno
,name
))
68 linecache
.checkcache(filename
)
69 line
= linecache
.getline(filename
, lineno
)
70 if line
: _print(file, ' ' + line
.strip())
74 def format_tb(tb
, limit
= None):
75 """A shorthand for 'format_list(extract_stack(f, limit))."""
76 return format_list(extract_tb(tb
, limit
))
78 def extract_tb(tb
, limit
= None):
79 """Return list of up to limit pre-processed entries from traceback.
81 This is useful for alternate formatting of stack traces. If
82 'limit' is omitted or None, all entries are extracted. A
83 pre-processed stack trace entry is a quadruple (filename, line
84 number, function name, text) representing the information that is
85 usually printed for a stack trace. The text is a string with
86 leading and trailing whitespace stripped; if the source is not
90 if hasattr(sys
, 'tracebacklimit'):
91 limit
= sys
.tracebacklimit
94 while tb
is not None and (limit
is None or n
< limit
):
98 filename
= co
.co_filename
100 linecache
.checkcache(filename
)
101 line
= linecache
.getline(filename
, lineno
)
102 if line
: line
= line
.strip()
104 list.append((filename
, lineno
, name
, line
))
110 def print_exception(etype
, value
, tb
, limit
=None, file=None):
111 """Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
113 This differs from print_tb() in the following ways: (1) if
114 traceback is not None, it prints a header "Traceback (most recent
115 call last):"; (2) it prints the exception type and value after the
116 stack trace; (3) if type is SyntaxError and value has the
117 appropriate format, it prints the line where the syntax error
118 occurred with a caret on the next line indicating the approximate
119 position of the error.
124 _print(file, 'Traceback (most recent call last):')
125 print_tb(tb
, limit
, file)
126 lines
= format_exception_only(etype
, value
)
127 for line
in lines
[:-1]:
128 _print(file, line
, ' ')
129 _print(file, lines
[-1], '')
131 def format_exception(etype
, value
, tb
, limit
= None):
132 """Format a stack trace and the exception information.
134 The arguments have the same meaning as the corresponding arguments
135 to print_exception(). The return value is a list of strings, each
136 ending in a newline and some containing internal newlines. When
137 these lines are concatenated and printed, exactly the same text is
138 printed as does print_exception().
141 list = ['Traceback (most recent call last):\n']
142 list = list + format_tb(tb
, limit
)
145 list = list + format_exception_only(etype
, value
)
148 def format_exception_only(etype
, value
):
149 """Format the exception part of a traceback.
151 The arguments are the exception type and value such as given by
152 sys.last_type and sys.last_value. The return value is a list of
153 strings, each ending in a newline. Normally, the list contains a
154 single string; however, for SyntaxError exceptions, it contains
155 several lines that (when printed) display detailed information
156 about where the syntax error occurred. The message indicating
157 which exception occurred is the always last string in the list.
160 if type(etype
) == types
.ClassType
:
161 stype
= etype
.__name
__
165 list.append(str(stype
) + '\n')
167 if etype
is SyntaxError:
169 msg
, (filename
, lineno
, offset
, line
) = value
173 if not filename
: filename
= "<string>"
174 list.append(' File "%s", line %d\n' %
178 while i
< len(line
) and line
[i
].isspace():
180 list.append(' %s\n' % line
.strip())
181 if offset
is not None:
183 for c
in line
[i
:offset
-1]:
188 list.append('%s^\n' % s
)
192 list.append('%s: %s\n' % (str(stype
), s
))
194 list.append('%s\n' % str(stype
))
197 def _some_str(value
):
201 return '<unprintable %s object>' % type(value
).__name
__
204 def print_exc(limit
=None, file=None):
205 """Shorthand for 'print_exception(sys.exc_type, sys.exc_value, sys.exc_traceback, limit, file)'.
206 (In fact, it uses sys.exc_info() to retrieve the same information
207 in a thread-safe way.)"""
211 etype
, value
, tb
= sys
.exc_info()
212 print_exception(etype
, value
, tb
, limit
, file)
214 etype
= value
= tb
= None
217 def format_exc(limit
=None):
218 """Like print_exc() but return a string."""
220 etype
, value
, tb
= sys
.exc_info()
221 return ''.join(format_exception(etype
, value
, tb
, limit
))
223 etype
= value
= tb
= None
226 def print_last(limit
=None, file=None):
227 """This is a shorthand for 'print_exception(sys.last_type,
228 sys.last_value, sys.last_traceback, limit, file)'."""
231 print_exception(sys
.last_type
, sys
.last_value
, sys
.last_traceback
,
235 def print_stack(f
=None, limit
=None, file=None):
236 """Print a stack trace from its invocation point.
238 The optional 'f' argument can be used to specify an alternate
239 stack frame at which to start. The optional 'limit' and 'file'
240 arguments have the same meaning as for print_exception().
244 raise ZeroDivisionError
245 except ZeroDivisionError:
246 f
= sys
.exc_info()[2].tb_frame
.f_back
247 print_list(extract_stack(f
, limit
), file)
249 def format_stack(f
=None, limit
=None):
250 """Shorthand for 'format_list(extract_stack(f, limit))'."""
253 raise ZeroDivisionError
254 except ZeroDivisionError:
255 f
= sys
.exc_info()[2].tb_frame
.f_back
256 return format_list(extract_stack(f
, limit
))
258 def extract_stack(f
=None, limit
= None):
259 """Extract the raw traceback from the current stack frame.
261 The return value has the same format as for extract_tb(). The
262 optional 'f' and 'limit' arguments have the same meaning as for
263 print_stack(). Each item in the list is a quadruple (filename,
264 line number, function name, text), and the entries are in order
265 from oldest to newest stack frame.
269 raise ZeroDivisionError
270 except ZeroDivisionError:
271 f
= sys
.exc_info()[2].tb_frame
.f_back
273 if hasattr(sys
, 'tracebacklimit'):
274 limit
= sys
.tracebacklimit
277 while f
is not None and (limit
is None or n
< limit
):
280 filename
= co
.co_filename
282 linecache
.checkcache(filename
)
283 line
= linecache
.getline(filename
, lineno
)
284 if line
: line
= line
.strip()
286 list.append((filename
, lineno
, name
, line
))
293 """Calculate correct line number of traceback given in tb.