| :mod:`bdb` --- Debugger framework |
| ================================= |
| |
| .. module:: bdb |
| :synopsis: Debugger framework. |
| |
| **Source code:** :source:`Lib/bdb.py` |
| |
| -------------- |
| |
| The :mod:`bdb` module handles basic debugger functions, like setting breakpoints |
| or managing execution via the debugger. |
| |
| The following exception is defined: |
| |
| .. exception:: BdbQuit |
| |
| Exception raised by the :class:`Bdb` class for quitting the debugger. |
| |
| |
| The :mod:`bdb` module also defines two classes: |
| |
| .. class:: Breakpoint(self, file, line, temporary=False, cond=None, funcname=None) |
| |
| This class implements temporary breakpoints, ignore counts, disabling and |
| (re-)enabling, and conditionals. |
| |
| Breakpoints are indexed by number through a list called :attr:`bpbynumber` |
| and by ``(file, line)`` pairs through :attr:`bplist`. The former points to |
| a single instance of class :class:`Breakpoint`. The latter points to a list |
| of such instances since there may be more than one breakpoint per line. |
| |
| When creating a breakpoint, its associated :attr:`file name <file>` should |
| be in canonical form. If a :attr:`funcname` is defined, a breakpoint |
| :attr:`hit <hits>` will be counted when the first line of that function is |
| executed. A :attr:`conditional <cond>` breakpoint always counts a |
| :attr:`hit <hits>`. |
| |
| :class:`Breakpoint` instances have the following methods: |
| |
| .. method:: deleteMe() |
| |
| Delete the breakpoint from the list associated to a file/line. If it is |
| the last breakpoint in that position, it also deletes the entry for the |
| file/line. |
| |
| |
| .. method:: enable() |
| |
| Mark the breakpoint as enabled. |
| |
| |
| .. method:: disable() |
| |
| Mark the breakpoint as disabled. |
| |
| |
| .. method:: bpformat() |
| |
| Return a string with all the information about the breakpoint, nicely |
| formatted: |
| |
| * Breakpoint number. |
| * Temporary status (del or keep). |
| * File/line position. |
| * Break condition. |
| * Number of times to ignore. |
| * Number of times hit. |
| |
| .. versionadded:: 3.2 |
| |
| .. method:: bpprint(out=None) |
| |
| Print the output of :meth:`bpformat` to the file *out*, or if it is |
| ``None``, to standard output. |
| |
| :class:`Breakpoint` instances have the following attributes: |
| |
| .. attribute:: file |
| |
| File name of the :class:`Breakpoint`. |
| |
| .. attribute:: line |
| |
| Line number of the :class:`Breakpoint` within :attr:`file`. |
| |
| .. attribute:: temporary |
| |
| True if a :class:`Breakpoint` at (file, line) is temporary. |
| |
| .. attribute:: cond |
| |
| Condition for evaluating a :class:`Breakpoint` at (file, line). |
| |
| .. attribute:: funcname |
| |
| Function name that defines whether a :class:`Breakpoint` is hit upon |
| entering the function. |
| |
| .. attribute:: enabled |
| |
| True if :class:`Breakpoint` is enabled. |
| |
| .. attribute:: bpbynumber |
| |
| Numeric index for a single instance of a :class:`Breakpoint`. |
| |
| .. attribute:: bplist |
| |
| Dictionary of :class:`Breakpoint` instances indexed by |
| (:attr:`file`, :attr:`line`) tuples. |
| |
| .. attribute:: ignore |
| |
| Number of times to ignore a :class:`Breakpoint`. |
| |
| .. attribute:: hits |
| |
| Count of the number of times a :class:`Breakpoint` has been hit. |
| |
| .. class:: Bdb(skip=None) |
| |
| The :class:`Bdb` class acts as a generic Python debugger base class. |
| |
| This class takes care of the details of the trace facility; a derived class |
| should implement user interaction. The standard debugger class |
| (:class:`pdb.Pdb`) is an example. |
| |
| The *skip* argument, if given, must be an iterable of glob-style |
| module name patterns. The debugger will not step into frames that |
| originate in a module that matches one of these patterns. Whether a |
| frame is considered to originate in a certain module is determined |
| by the ``__name__`` in the frame globals. |
| |
| .. versionadded:: 3.1 |
| The *skip* argument. |
| |
| The following methods of :class:`Bdb` normally don't need to be overridden. |
| |
| .. method:: canonic(filename) |
| |
| Return canonical form of *filename*. |
| |
| For real file names, the canonical form is an operating-system-dependent, |
| :func:`case-normalized <os.path.normcase>` :func:`absolute path |
| <os.path.abspath>`. A *filename* with angle brackets, such as `"<stdin>"` |
| generated in interactive mode, is returned unchanged. |
| |
| .. method:: reset() |
| |
| Set the :attr:`botframe`, :attr:`stopframe`, :attr:`returnframe` and |
| :attr:`quitting` attributes with values ready to start debugging. |
| |
| .. method:: trace_dispatch(frame, event, arg) |
| |
| This function is installed as the trace function of debugged frames. Its |
| return value is the new trace function (in most cases, that is, itself). |
| |
| The default implementation decides how to dispatch a frame, depending on |
| the type of event (passed as a string) that is about to be executed. |
| *event* can be one of the following: |
| |
| * ``"line"``: A new line of code is going to be executed. |
| * ``"call"``: A function is about to be called, or another code block |
| entered. |
| * ``"return"``: A function or other code block is about to return. |
| * ``"exception"``: An exception has occurred. |
| * ``"c_call"``: A C function is about to be called. |
| * ``"c_return"``: A C function has returned. |
| * ``"c_exception"``: A C function has raised an exception. |
| |
| For the Python events, specialized functions (see below) are called. For |
| the C events, no action is taken. |
| |
| The *arg* parameter depends on the previous event. |
| |
| See the documentation for :func:`sys.settrace` for more information on the |
| trace function. For more information on code and frame objects, refer to |
| :ref:`types`. |
| |
| .. method:: dispatch_line(frame) |
| |
| If the debugger should stop on the current line, invoke the |
| :meth:`user_line` method (which should be overridden in subclasses). |
| Raise a :exc:`BdbQuit` exception if the :attr:`Bdb.quitting` flag is set |
| (which can be set from :meth:`user_line`). Return a reference to the |
| :meth:`trace_dispatch` method for further tracing in that scope. |
| |
| .. method:: dispatch_call(frame, arg) |
| |
| If the debugger should stop on this function call, invoke the |
| :meth:`user_call` method (which should be overridden in subclasses). |
| Raise a :exc:`BdbQuit` exception if the :attr:`Bdb.quitting` flag is set |
| (which can be set from :meth:`user_call`). Return a reference to the |
| :meth:`trace_dispatch` method for further tracing in that scope. |
| |
| .. method:: dispatch_return(frame, arg) |
| |
| If the debugger should stop on this function return, invoke the |
| :meth:`user_return` method (which should be overridden in subclasses). |
| Raise a :exc:`BdbQuit` exception if the :attr:`Bdb.quitting` flag is set |
| (which can be set from :meth:`user_return`). Return a reference to the |
| :meth:`trace_dispatch` method for further tracing in that scope. |
| |
| .. method:: dispatch_exception(frame, arg) |
| |
| If the debugger should stop at this exception, invokes the |
| :meth:`user_exception` method (which should be overridden in subclasses). |
| Raise a :exc:`BdbQuit` exception if the :attr:`Bdb.quitting` flag is set |
| (which can be set from :meth:`user_exception`). Return a reference to the |
| :meth:`trace_dispatch` method for further tracing in that scope. |
| |
| Normally derived classes don't override the following methods, but they may |
| if they want to redefine the definition of stopping and breakpoints. |
| |
| .. method:: is_skipped_line(module_name) |
| |
| Return True if *module_name* matches any skip pattern. |
| |
| .. method:: stop_here(frame) |
| |
| Return True if *frame* is below the starting frame in the stack. |
| |
| .. method:: break_here(frame) |
| |
| Return True if there is an effective breakpoint for this line. |
| |
| Check whether a line or function breakpoint exists and is in effect. Delete temporary |
| breakpoints based on information from :func:`effective`. |
| |
| .. method:: break_anywhere(frame) |
| |
| Return True if any breakpoint exists for *frame*'s filename. |
| |
| Derived classes should override these methods to gain control over debugger |
| operation. |
| |
| .. method:: user_call(frame, argument_list) |
| |
| Called from :meth:`dispatch_call` if a break might stop inside the |
| called function. |
| |
| .. method:: user_line(frame) |
| |
| Called from :meth:`dispatch_line` when either :meth:`stop_here` or |
| :meth:`break_here` returns ``True``. |
| |
| .. method:: user_return(frame, return_value) |
| |
| Called from :meth:`dispatch_return` when :meth:`stop_here` returns ``True``. |
| |
| .. method:: user_exception(frame, exc_info) |
| |
| Called from :meth:`dispatch_exception` when :meth:`stop_here` |
| returns ``True``. |
| |
| .. method:: do_clear(arg) |
| |
| Handle how a breakpoint must be removed when it is a temporary one. |
| |
| This method must be implemented by derived classes. |
| |
| |
| Derived classes and clients can call the following methods to affect the |
| stepping state. |
| |
| .. method:: set_step() |
| |
| Stop after one line of code. |
| |
| .. method:: set_next(frame) |
| |
| Stop on the next line in or below the given frame. |
| |
| .. method:: set_return(frame) |
| |
| Stop when returning from the given frame. |
| |
| .. method:: set_until(frame, lineno=None) |
| |
| Stop when the line with the *lineno* greater than the current one is |
| reached or when returning from current frame. |
| |
| .. method:: set_trace([frame]) |
| |
| Start debugging from *frame*. If *frame* is not specified, debugging |
| starts from caller's frame. |
| |
| .. method:: set_continue() |
| |
| Stop only at breakpoints or when finished. If there are no breakpoints, |
| set the system trace function to ``None``. |
| |
| .. method:: set_quit() |
| |
| Set the :attr:`quitting` attribute to ``True``. This raises :exc:`BdbQuit` in |
| the next call to one of the :meth:`dispatch_\*` methods. |
| |
| |
| Derived classes and clients can call the following methods to manipulate |
| breakpoints. These methods return a string containing an error message if |
| something went wrong, or ``None`` if all is well. |
| |
| .. method:: set_break(filename, lineno, temporary=False, cond=None, funcname=None) |
| |
| Set a new breakpoint. If the *lineno* line doesn't exist for the |
| *filename* passed as argument, return an error message. The *filename* |
| should be in canonical form, as described in the :meth:`canonic` method. |
| |
| .. method:: clear_break(filename, lineno) |
| |
| Delete the breakpoints in *filename* and *lineno*. If none were set, |
| return an error message. |
| |
| .. method:: clear_bpbynumber(arg) |
| |
| Delete the breakpoint which has the index *arg* in the |
| :attr:`Breakpoint.bpbynumber`. If *arg* is not numeric or out of range, |
| return an error message. |
| |
| .. method:: clear_all_file_breaks(filename) |
| |
| Delete all breakpoints in *filename*. If none were set, return an error |
| message. |
| |
| .. method:: clear_all_breaks() |
| |
| Delete all existing breakpoints. If none were set, return an error |
| message. |
| |
| .. method:: get_bpbynumber(arg) |
| |
| Return a breakpoint specified by the given number. If *arg* is a string, |
| it will be converted to a number. If *arg* is a non-numeric string, if |
| the given breakpoint never existed or has been deleted, a |
| :exc:`ValueError` is raised. |
| |
| .. versionadded:: 3.2 |
| |
| .. method:: get_break(filename, lineno) |
| |
| Return True if there is a breakpoint for *lineno* in *filename*. |
| |
| .. method:: get_breaks(filename, lineno) |
| |
| Return all breakpoints for *lineno* in *filename*, or an empty list if |
| none are set. |
| |
| .. method:: get_file_breaks(filename) |
| |
| Return all breakpoints in *filename*, or an empty list if none are set. |
| |
| .. method:: get_all_breaks() |
| |
| Return all breakpoints that are set. |
| |
| |
| Derived classes and clients can call the following methods to get a data |
| structure representing a stack trace. |
| |
| .. method:: get_stack(f, t) |
| |
| Return a list of (frame, lineno) tuples in a stack trace, and a size. |
| |
| The most recently called frame is last in the list. The size is the number |
| of frames below the frame where the debugger was invoked. |
| |
| .. method:: format_stack_entry(frame_lineno, lprefix=': ') |
| |
| Return a string with information about a stack entry, which is a |
| ``(frame, lineno)`` tuple. The return string contains: |
| |
| * The canonical filename which contains the frame. |
| * The function name or ``"<lambda>"``. |
| * The input arguments. |
| * The return value. |
| * The line of code (if it exists). |
| |
| |
| The following two methods can be called by clients to use a debugger to debug |
| a :term:`statement`, given as a string. |
| |
| .. method:: run(cmd, globals=None, locals=None) |
| |
| Debug a statement executed via the :func:`exec` function. *globals* |
| defaults to :attr:`__main__.__dict__`, *locals* defaults to *globals*. |
| |
| .. method:: runeval(expr, globals=None, locals=None) |
| |
| Debug an expression executed via the :func:`eval` function. *globals* and |
| *locals* have the same meaning as in :meth:`run`. |
| |
| .. method:: runctx(cmd, globals, locals) |
| |
| For backwards compatibility. Calls the :meth:`run` method. |
| |
| .. method:: runcall(func, /, *args, **kwds) |
| |
| Debug a single function call, and return its result. |
| |
| |
| Finally, the module defines the following functions: |
| |
| .. function:: checkfuncname(b, frame) |
| |
| Return True if we should break here, depending on the way the |
| :class:`Breakpoint` *b* was set. |
| |
| If it was set via line number, it checks if |
| :attr:`b.line <bdb.Breakpoint.line>` is the same as the one in *frame*. |
| If the breakpoint was set via |
| :attr:`function name <bdb.Breakpoint.funcname>`, we have to check we are in |
| the right *frame* (the right function) and if we are on its first executable |
| line. |
| |
| .. function:: effective(file, line, frame) |
| |
| Return ``(active breakpoint, delete temporary flag)`` or ``(None, None)`` as the |
| breakpoint to act upon. |
| |
| The *active breakpoint* is the first entry in |
| :attr:`bplist <bdb.Breakpoint.bplist>` for the |
| (:attr:`file <bdb.Breakpoint.file>`, :attr:`line <bdb.Breakpoint.line>`) |
| (which must exist) that is :attr:`enabled <bdb.Breakpoint.enabled>`, for |
| which :func:`checkfuncname` is True, and that has neither a False |
| :attr:`condition <bdb.Breakpoint.cond>` nor positive |
| :attr:`ignore <bdb.Breakpoint.ignore>` count. The *flag*, meaning that a |
| temporary breakpoint should be deleted, is False only when the |
| :attr:`cond <bdb.Breakpoint.cond>` cannot be evaluated (in which case, |
| :attr:`ignore <bdb.Breakpoint.ignore>` count is ignored). |
| |
| If no such entry exists, then (None, None) is returned. |
| |
| |
| .. function:: set_trace() |
| |
| Start debugging with a :class:`Bdb` instance from caller's frame. |