PythonbdbDebuggerframework

• Z时代
• 2024-01-10
• 分类：综合

Source code: Lib/bdb.py

The bdb module handles basic debugger functions, like setting breakpoints

or managing execution via the debugger.

定义了以下异常：

exception bdb.BdbQuit¶

Exception raised by the Bdb class for quitting the debugger.

The bdb module also defines two classes:

class bdb.Breakpoint(self, file, line, temporary=0, 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 bpbynumber

and by (file,line) pairs through bplist. The former points to a

single instance of 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 filename should be in canonical

form. If a funcname is defined, a breakpoint hit will be counted when the

first line of that function is executed. A conditional breakpoint always

counts a hit.

Breakpoint instances have the following methods:

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.

enable()¶

Mark the breakpoint as enabled.

disable()¶

Mark the breakpoint as disabled.

bpformat()¶

Return a string with all the information about the breakpoint, nicely

formatted:

• The breakpoint number.

• If it is temporary or not.

• Its file,line position.

• The condition that causes a break.

• If it must be ignored the next N times.

• The breakpoint hit count.

3.2 新版功能.

bpprint(out=None)¶

Print the output of bpformat() to the file out, or if it is

None, to standard output.

class bdb.Bdb(skip=None)¶

The 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

(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.

3.1 新版功能: skip 参数。

The following methods of Bdb normally don't need to be overridden.

canonic(filename)¶

Auxiliary method for getting a filename in a canonical form, that is, as a

case-normalized (on case-insensitive filesystems) absolute path, stripped

of surrounding angle brackets.

reset()¶

Set the botframe, stopframe, returnframe and

quitting attributes with values ready to start debugging.

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 sys.settrace() for more information on the

trace function. For more information on code and frame objects, refer to

标准类型层级结构.

dispatch_line(frame)¶

If the debugger should stop on the current line, invoke the

user_line() method (which should be overridden in subclasses).

Raise a BdbQuit exception if the Bdb.quitting flag is set

(which can be set from user_line()). Return a reference to the

trace_dispatch() method for further tracing in that scope.

dispatch_call(frame, arg)¶

If the debugger should stop on this function call, invoke the

user_call() method (which should be overridden in subclasses).

Raise a BdbQuit exception if the Bdb.quitting flag is set

(which can be set from user_call()). Return a reference to the

trace_dispatch() method for further tracing in that scope.

dispatch_return(frame, arg)¶

If the debugger should stop on this function return, invoke the

user_return() method (which should be overridden in subclasses).

Raise a BdbQuit exception if the Bdb.quitting flag is set

(which can be set from user_return()). Return a reference to the

trace_dispatch() method for further tracing in that scope.

dispatch_exception(frame, arg)¶

If the debugger should stop at this exception, invokes the

user_exception() method (which should be overridden in subclasses).

Raise a BdbQuit exception if the Bdb.quitting flag is set

(which can be set from user_exception()). Return a reference to the

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.

stop_here(frame)¶

This method checks if the frame is somewhere below botframe in

the call stack. botframe is the frame in which debugging started.

break_here(frame)¶

This method checks if there is a breakpoint in the filename and line

belonging to frame or, at least, in the current function. If the

breakpoint is a temporary one, this method deletes it.

break_anywhere(frame)¶

This method checks if there is a breakpoint in the filename of the current

frame.

Derived classes should override these methods to gain control over debugger

operation.

user_call(frame, argument_list)¶

This method is called from dispatch_call() when there is the

possibility that a break might be necessary anywhere inside the called

function.

user_line(frame)¶

This method is called from dispatch_line() when either

stop_here() or break_here() yields True.

user_return(frame, return_value)¶

This method is called from dispatch_return() when stop_here()

yields True.

user_exception(frame, exc_info)¶

This method is called from dispatch_exception() when

stop_here() yields True.

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.

set_step()¶

Stop after one line of code.

set_next(frame)¶

Stop on the next line in or below the given frame.

set_return(frame)¶

Stop when returning from the given frame.

set_until(frame)¶

Stop when the line with the line no greater than the current one is

reached or when returning from current frame.

set_trace([frame])¶

Start debugging from frame. If frame is not specified, debugging

starts from caller's frame.

set_continue()¶

Stop only at breakpoints or when finished. If there are no breakpoints,

set the system trace function to None.

set_quit()¶

Set the quitting attribute to True. This raises BdbQuit in

the next call to one of the 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.

set_break(filename, lineno, temporary=0, cond, funcname)¶

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 canonic() method.

clear_break(filename, lineno)¶

Delete the breakpoints in filename and lineno. If none were set, an

error message is returned.

clear_bpbynumber(arg)¶

Delete the breakpoint which has the index arg in the

Breakpoint.bpbynumber. If arg is not numeric or out of range,

return an error message.

clear_all_file_breaks(filename)¶

Delete all breakpoints in filename. If none were set, an error message

is returned.

clear_all_breaks()¶

Delete all existing breakpoints.

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

ValueError is raised.

3.2 新版功能.

get_break(filename, lineno)¶

Check if there is a breakpoint for lineno of filename.

get_breaks(filename, lineno)¶

Return all breakpoints for lineno in filename, or an empty list if

none are set.

get_file_breaks(filename)¶

Return all breakpoints in filename, or an empty list if none are set.

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.

get_stack(f, t)¶

Get a list of records for a frame and all higher (calling) and lower

frames, and the size of the higher part.

format_stack_entry(frame_lineno, lprefix=': ')¶

Return a string with information about a stack entry, identified by a

(frame,lineno) tuple:

• The canonical form of the 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 statement, given as a string.

run(cmd, globals=None, locals=None)¶

Debug a statement executed via the exec() function. globals

defaults to __main__.__dict__, locals defaults to globals.

runeval(expr, globals=None, locals=None)¶

Debug an expression executed via the eval() function. globals and

locals have the same meaning as in run().

runctx(cmd, globals, locals)¶

For backwards compatibility. Calls the run() method.

runcall(func, *args, **kwds)¶

Debug a single function call, and return its result.

Finally, the module defines the following functions:

bdb.checkfuncname(b, frame)¶

Check whether we should break here, depending on the way the breakpoint b

was set.

If it was set via line number, it checks if b.line is the same as the one

in the frame also passed as argument. If the breakpoint was set via function

name, we have to check we are in the right frame (the right function) and if

we are in its first executable line.

bdb.effective(file, line, frame)¶

Determine if there is an effective (active) breakpoint at this line of code.

Return a tuple of the breakpoint and a boolean that indicates if it is ok

to delete a temporary breakpoint. Return (None,None) if there is no

matching breakpoint.

bdb.set_trace()¶

Start debugging with a Bdb instance from caller's frame.