Python sys.last_type() Examples

def pytest_runtest_call(item: Item) -> None:
    _update_current_test_var(item, "call")
    try:
        del sys.last_type
        del sys.last_value
        del sys.last_traceback
    except AttributeError:
        pass
    try:
        item.runtest()
    except Exception as e:
        # Store trace info to allow postmortem debugging
        sys.last_type = type(e)
        sys.last_value = e
        assert e.__traceback__ is not None
        # Skip *this* frame
        sys.last_traceback = e.__traceback__.tb_next
        raise e 

def test_base_exception(self):
        # Test that exceptions derived from BaseException are formatted right
        e = KeyboardInterrupt()
        lst = traceback.format_exception_only(e.__class__, e)
        self.assertEqual(lst, ['KeyboardInterrupt\n'])

    # String exceptions are deprecated, but legal.  The quirky form with
    # separate "type" and "value" tends to break things, because
    #     not isinstance(value, type)
    # and a string cannot be the first argument to issubclass.
    #
    # Note that sys.last_type and sys.last_value do not get set if an
    # exception is caught, so we sort of cheat and just emulate them.
    #
    # test_string_exception1 is equivalent to
    #
    # >>> raise "String Exception"
    #
    # test_string_exception2 is equivalent to
    #
    # >>> raise "String Exception", "String Value"
    # 

def run_with_api(self, code):
        """Run code with didyoumean after enabling didyoumean hook."""
        prev_hook = sys.excepthook
        self.assertEqual(prev_hook, sys.excepthook)
        didyoumean_enablehook()
        self.assertNotEqual(prev_hook, sys.excepthook)
        try:
            no_exception(code)
        except:
            last_type, last_value, last_traceback = sys.exc_info()
            with suppress_stderr():
                sys.excepthook(last_type, last_value, last_traceback)
            raise
        finally:
            self.assertNotEqual(prev_hook, sys.excepthook)
            didyoumean_disablehook()
            self.assertEqual(prev_hook, sys.excepthook) 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, list) 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, list) 

def test_base_exception(self):
        # Test that exceptions derived from BaseException are formatted right
        e = KeyboardInterrupt()
        lst = traceback.format_exception_only(e.__class__, e)
        self.assertEqual(lst, ['KeyboardInterrupt\n'])

    # String exceptions are deprecated, but legal.  The quirky form with
    # separate "type" and "value" tends to break things, because
    #     not isinstance(value, type)
    # and a string cannot be the first argument to issubclass.
    #
    # Note that sys.last_type and sys.last_value do not get set if an
    # exception is caught, so we sort of cheat and just emulate them.
    #
    # test_string_exception1 is equivalent to
    #
    # >>> raise "String Exception"
    #
    # test_string_exception2 is equivalent to
    #
    # >>> raise "String Exception", "String Value"
    # 

def format(self, record):
        base = '[{} {} {}] '.format(record.levelname[0],
                                    time.strftime('%H:%M:%S'),
                                    record.name)
        if isinstance(record.msg, Exception):
            # Get excepion info and skip first frames
            type_, value, tb = sys.exc_info()
            for _ in range(getattr(value, 'skip_tb', 0)):
                tb = tb.tb_next
            # Enable post mortem debugging
            sys.last_type = type_
            sys.last_value = value
            sys.last_traceback = tb
            # Compose message
            cname = type_.__name__
            out = ''.join(traceback.format_list(traceback.extract_tb(tb)))
            del tb  # we don't want to hold too much references to this
            return base + cname + ': ' + str(value) + '\n' + out.rstrip()
        else:
            out = base + str(record.msg % record.args)
            if self.prepend_caller:
                part1, part2 = out.split(':', 1)
                out = part1 + ' ' + record.funcName + '():' + part2
            return out 

def _stack_viewer(parent):
    root = tk.Tk()
    root.title("Test StackViewer")
    width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
    root.geometry("+%d+%d"%(x, y + 150))
    flist = PyShellFileList(root)
    try: # to obtain a traceback object
        intentional_name_error
    except NameError:
        exc_type, exc_value, exc_tb = sys.exc_info()

    # inject stack trace to sys
    sys.last_type = exc_type
    sys.last_value = exc_value
    sys.last_traceback = exc_tb

    StackBrowser(root, flist=flist, top=root, tb=exc_tb)

    # restore sys to original state
    del sys.last_type
    del sys.last_value
    del sys.last_traceback 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, list) 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, list) 

def test_base_exception(self):
        # Test that exceptions derived from BaseException are formatted right
        e = KeyboardInterrupt()
        lst = traceback.format_exception_only(e.__class__, e)
        self.assertEqual(lst, ['KeyboardInterrupt\n'])

    # String exceptions are deprecated, but legal.  The quirky form with
    # separate "type" and "value" tends to break things, because
    #     not isinstance(value, type)
    # and a string cannot be the first argument to issubclass.
    #
    # Note that sys.last_type and sys.last_value do not get set if an
    # exception is caught, so we sort of cheat and just emulate them.
    #
    # test_string_exception1 is equivalent to
    #
    # >>> raise "String Exception"
    #
    # test_string_exception2 is equivalent to
    #
    # >>> raise "String Exception", "String Value"
    # 

def print_exception():
    import linecache
    linecache.checkcache()
    flush_stdout()
    efile = sys.stderr
    typ, val, tb = excinfo = sys.exc_info()
    sys.last_type, sys.last_value, sys.last_traceback = excinfo
    tbe = traceback.extract_tb(tb)
    print>>efile, '\nTraceback (most recent call last):'
    exclude = ("run.py", "rpc.py", "threading.py", "Queue.py",
               "RemoteDebugger.py", "bdb.py")
    cleanup_traceback(tbe, exclude)
    traceback.print_list(tbe, file=efile)
    lines = traceback.format_exception_only(typ, val)
    for line in lines:
        print>>efile, line, 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        sys.last_type, sys.last_value, last_tb = ei = sys.exc_info()
        sys.last_traceback = last_tb
        try:
            lines = traceback.format_exception(ei[0], ei[1], last_tb.tb_next)
            if sys.excepthook is sys.__excepthook__:
                self.write(''.join(lines))
            else:
                # If someone has set sys.excepthook, we let that take precedence
                # over self.write
                sys.excepthook(ei[0], ei[1], last_tb)
        finally:
            last_tb = ei = None 

def _stack_viewer(parent):
    root = tk.Tk()
    root.title("Test StackViewer")
    width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
    root.geometry("+%d+%d"%(x, y + 150))
    flist = PyShellFileList(root)
    try: # to obtain a traceback object
        intentional_name_error
    except NameError:
        exc_type, exc_value, exc_tb = sys.exc_info()

    # inject stack trace to sys
    sys.last_type = exc_type
    sys.last_value = exc_value
    sys.last_traceback = exc_tb

    StackBrowser(root, flist=flist, top=root, tb=exc_tb)

    # restore sys to original state
    del sys.last_type
    del sys.last_value
    del sys.last_traceback 

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.

    """
    return list(_format_exception_only_iter(etype, value)) 

def showtraceback(self, *args, **kwargs):
        """Display the exception that just occurred."""
        # Override for avoid using sys.excepthook PY-12600
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            lines = traceback.format_list(tblist)
            if lines:
                lines.insert(0, "Traceback (most recent call last):\n")
            lines.extend(traceback.format_exception_only(type, value))
        finally:
            tblist = tb = None
        sys.stderr.write(''.join(lines)) 

def showsyntaxerror(self, filename=None):
        """Display the syntax error that just occurred."""
        # Override for avoid using sys.excepthook PY-12600
        type, value, tb = sys.exc_info()
        sys.last_type = type
        sys.last_value = value
        sys.last_traceback = tb
        if filename and type is SyntaxError:
            # Work hard to stuff the correct filename in the exception
            try:
                msg, (dummy_filename, lineno, offset, line) = value.args
            except ValueError:
                # Not the format we expect; leave it alone
                pass
            else:
                # Stuff in the right filename
                value = SyntaxError(msg, (filename, lineno, offset, line))
                sys.last_value = value
        list = traceback.format_exception_only(type, value)
        sys.stderr.write(''.join(list)) 

def showtraceback(self, *args, **kwargs):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, 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.

    """
    return list(TracebackException(etype, value, None).format_exception_only())


# -- not offical API but folk probably use these two functions. 

def _stack_viewer(parent):
    root = tk.Tk()
    root.title("Test StackViewer")
    width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
    root.geometry("+%d+%d"%(x, y + 150))
    flist = PyShellFileList(root)
    try: # to obtain a traceback object
        intentional_name_error
    except NameError:
        exc_type, exc_value, exc_tb = sys.exc_info()

    # inject stack trace to sys
    sys.last_type = exc_type
    sys.last_value = exc_value
    sys.last_traceback = exc_tb

    StackBrowser(root, flist=flist, top=root, tb=exc_tb)

    # restore sys to original state
    del sys.last_type
    del sys.last_value
    del sys.last_traceback 

def print_exception():
    import linecache
    linecache.checkcache()
    flush_stdout()
    efile = sys.stderr
    typ, val, tb = excinfo = sys.exc_info()
    sys.last_type, sys.last_value, sys.last_traceback = excinfo
    tbe = traceback.extract_tb(tb)
    print>>efile, '\nTraceback (most recent call last):'
    exclude = ("run.py", "rpc.py", "threading.py", "Queue.py",
               "RemoteDebugger.py", "bdb.py")
    cleanup_traceback(tbe, exclude)
    traceback.print_list(tbe, file=efile)
    lines = traceback.format_exception_only(typ, val)
    for line in lines:
        print>>efile, line, 

def test_base_exception(self):
        # Test that exceptions derived from BaseException are formatted right
        e = KeyboardInterrupt()
        lst = traceback.format_exception_only(e.__class__, e)
        self.assertEqual(lst, ['KeyboardInterrupt\n'])

    # String exceptions are deprecated, but legal.  The quirky form with
    # separate "type" and "value" tends to break things, because
    #     not isinstance(value, type)
    # and a string cannot be the first argument to issubclass.
    #
    # Note that sys.last_type and sys.last_value do not get set if an
    # exception is caught, so we sort of cheat and just emulate them.
    #
    # test_string_exception1 is equivalent to
    #
    # >>> raise "String Exception"
    #
    # test_string_exception2 is equivalent to
    #
    # >>> raise "String Exception", "String Value"
    # 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        sys.last_type, sys.last_value, last_tb = ei = sys.exc_info()
        sys.last_traceback = last_tb
        try:
            lines = traceback.format_exception(ei[0], ei[1], last_tb.tb_next)
            if sys.excepthook is sys.__excepthook__:
                self.write(''.join(lines))
            else:
                # If someone has set sys.excepthook, we let that take precedence
                # over self.write
                sys.excepthook(ei[0], ei[1], last_tb)
        finally:
            last_tb = ei = None 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, list) 

def showtraceback(self):
        """Display the exception that just occurred.

        We remove the first stack item because it is our own code.

        The output is written by self.write(), below.

        """
        try:
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            tblist = traceback.extract_tb(tb)
            del tblist[:1]
            list = traceback.format_list(tblist)
            if list:
                list.insert(0, "Traceback (most recent call last):\n")
            list[len(list):] = traceback.format_exception_only(type, value)
        finally:
            tblist = tb = None
        map(self.write, 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.

    """
    return list(TracebackException(etype, value, None).format_exception_only())


# -- not official API but folk probably use these two functions. 

def showsyntaxerror(self, filename=None):
        """Display the syntax error that just occurred.

        This doesn't display a stack trace because there isn't one.

        If a filename is given, it is stuffed in the exception instead
        of what was there before (because Python's parser always uses
        "<string>" when reading from a string).

        The output is written by self.write(), below.

        """
        type, value, sys.last_traceback = sys.exc_info()
        sys.last_type = type
        sys.last_value = value
        if filename and type is SyntaxError:
            # Work hard to stuff the correct filename in the exception
            try:
                msg, (dummy_filename, lineno, offset, line) = value
            except:
                # Not the format we expect; leave it alone
                pass
            else:
                # Stuff in the right filename
                value = SyntaxError(msg, (filename, lineno, offset, line))
                sys.last_value = value
        list = traceback.format_exception_only(type, value)
        map(self.write, list) 

def showsyntaxerror(self, filename=None):
        """Display the syntax error that just occurred.

        This doesn't display a stack trace because there isn't one.

        If a filename is given, it is stuffed in the exception instead
        of what was there before (because Python's parser always uses
        "<string>" when reading from a string).

        The output is written by self.write(), below.

        """
        type, value, tb = sys.exc_info()
        sys.last_type = type
        sys.last_value = value
        sys.last_traceback = tb
        if filename and type is SyntaxError:
            # Work hard to stuff the correct filename in the exception
            try:
                msg, (dummy_filename, lineno, offset, line) = value.args
            except ValueError:
                # Not the format we expect; leave it alone
                pass
            else:
                # Stuff in the right filename
                value = SyntaxError(msg, (filename, lineno, offset, line))
                sys.last_value = value
        if sys.excepthook is sys.__excepthook__:
            lines = traceback.format_exception_only(type, value)
            self.write(''.join(lines))
        else:
            # If someone has set sys.excepthook, we let that take precedence
            # over self.write
            sys.excepthook(type, value, tb) 

def pm(*args, **kwargs):
    """Post-mortem function that searches the last exception."""

    if hasattr(sys, "last_type"):
        einfo = (sys.last_type, sys.last_value, sys.last_traceback)
        handler = ExceptionHandler(*args, **kwargs)
        try:
            ipython_shell = get_ipython()
            ipython_shell.showtraceback()
            handler.handle_error(*einfo)
        except NameError:
            handler(*einfo)
    else:
        raise ValueError("no last exception") 

def didyoumean_postmortem():
    """Post postem function to add suggestions to last exception thrown.

    Add suggestions to last exception thrown (in interactive mode) and
    return it (which should print it).
    """
    if hasattr(sys, 'last_type'):
        typ, val, trace = sys.last_type, sys.last_value, sys.last_traceback
        add_suggestions_to_exception(typ, val, trace)
        return val
    return None