|
This module provides a standard interface to extract, format and print stack traces of
Python programs. It exactly mimics the behavior of the Python interpreter when it prints a
stack trace. This is useful when you want to print stack traces under program control, such as
in a ``wrapper'' around the interpreter.
The module uses traceback objects -- this is the object type that is stored in the
variables sys.exc_traceback (deprecated) and sys.last_traceback and
returned as the third item from sys.exc_info().
The module defines the following functions:
-
| print_tb( |
traceback[, limit[, file]]) |
- Print up to limit stack trace entries from traceback. If limit
is omitted or
None, all entries are printed. If file is omitted or
None, the output goes to sys.stderr; otherwise it should be an
open file or file-like object to receive the output.
-
| print_exception( |
type, value, traceback[, limit[,
file]]) |
- Print exception information and up to limit stack trace entries from traceback
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 indicating the approximate
position of the error.
-
| print_exc( |
[limit[, file]]) |
- This is a 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
instead of using the deprecated variables.)
-
| print_last( |
[limit[, file]]) |
- This is a shorthand for
print_exception(sys.last_type, sys.last_value,
sys.last_traceback, limit, file).
-
| print_stack( |
[f[, limit[, file]]]) |
- This function prints a stack trace from its invocation point. The optional f
argument can be used to specify an alternate stack frame to start. The optional limit
and file arguments have the same meaning as for print_exception().
-
| extract_tb( |
traceback[, limit]) |
- Return a list of up to limit ``pre-processed'' stack trace entries extracted
from the traceback object traceback. It 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.
-
| extract_stack( |
[f[, limit]]) |
- 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().
-
- 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.
-
| format_exception_only( |
type, 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 the always last string
in the list.
-
| format_exception( |
type, value, tb[, limit]) |
- 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().
-
- A shorthand for
format_list(extract_tb(tb, limit)).
-
| format_stack( |
[f[, limit]]) |
- A shorthand for
format_list(extract_stack(f, limit)).
-
- This function returns the current line number set in the traceback object. This function
was necessary because in versions of Python prior to 2.3 when the -O
flag was passed to Python the
tb.tb_lineno was not updated
correctly. This function has no use in versions past 2.3.
|
