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.)
-
This is like
print_exc(limit) but returns a string
instead of printing to a file.
New in version 2.4.
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.
Release 2.5.2, documentation updated on 21st February, 2008.
See About this document... for information on suggesting changes.
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