diff options
| -rwxr-xr-x | Lib/pdb.py | 407 |
1 files changed, 300 insertions, 107 deletions
@@ -1,16 +1,157 @@ # pdb.py -- finally, a Python debugger! -# To do: -# - Keep a list of exceptions trapped (default only KeyboardInterrupt?) -# - A blank line should repeat the previous command, not execute 'next' -# - Don't line-trace functions (or at least files) without breakpoints -# - Better handling of call/return events -# - It should be possible to intercept KeyboardInterrupt completely -# - Where and when to stop exactly when 'next' encounters a return? -# (should be level-based -- don't trace anything deeper than current) -# - Show stack traces upside-down (like dbx/gdb) -# - When stopping on an exception, show traceback stack -# - Merge with tb (for post-mortem usage) +# To use the debugger in its simplest form: +# >>> import pdb +# >>> pdb.run('<a statement>') +# The debugger's prompt is '(Pdb) '. +# This will stop in the first function call in <a statement>. + +# The commands recognized by the debugger are listed below. +# Most can be abbreviated as indicated; e.g., h(elp) means that +# 'help' can be typed as 'h' or 'help' +# (but not as 'he' or 'hel', nor as 'H' or 'Help' or 'HELP'). +# Optional arguments are enclosed in square brackets. + +# A blank line repeats the previous command literally. +# (Except for 'list', where it lists the next 11 lines.) + +# Commands that the debugger does not recognized are assumed to +# be Python statements and are executed in the context of the +# program being debugged. +# Python statements can also be prefixed with an exclamation point ('!'). +# This is a powerful way to inspect the program being debugged; +# it is even possible to change variables. +# When an exception occurs in such a statement, the exception name +# is printed but the debugger's state is not changed. + +# The debugger is not directly programmable; but it is implemented +# as a class from which you can derive your own debugger class, +# so you can make as fancy as you like. + +# The debugger's commands are: + +# h(elp) +# Without argument, print the list of available commands. +# With a command name as argument, print help about that command +# (this is currently not implemented). + +# w(here) +# Print a stack trace, with the most recent frame at the bottom. +# An arrow indicates the "current frame", which determines the +# context of most commands. + +# d(own) +# Move the current frame one level down in the stack trace +# (to an older frame). + +# u(p) +# Move the current frame one level up in the stack trace +# (to a newer frame). + +# b(reak) [lineno] +# With a line number argument, set a break there in the current file. +# Without argument, list all breaks. + +# cl(ear) [lineno] +# With a line number argument, clear that break in the current file. +# Without argument, clear all breaks (but first ask confirmation). + +# s(tep) +# Execute the current line, stop at the first possible occasion +# (either in a function that is called or in the current function). + +# n(ext) +# Continue execution until the next line in the current function +# is reached or it returns. + +# r(eturn) +# Continue execution until the current function returns. + +# c(ont(inue)) +# Continue execution, only stop when a breakpoint is encountered. + +# l(ist) [first [,last]] +# List source code for the current file. +# Without arguments, list 11 lines around the current line +# or continue the previous listing. +# With one argument, list 11 lines starting at that line. +# With two arguments, list the given range; +# if the second argument is less than the first, it is a count. + +# a(rgs) +# Print the argument list of the current function. + +# p expression +# Print the value of the expression. + +# (!) statement +# Execute the (one-line) statement in the context of +# the current stack frame. +# The exclamation point can be omitted unless the first word +# of the statement resembles a debugger command. +# To assign to a global variable you must always prefix the +# command with a 'global' command, e.g.: +# (Pdb) global list_options; list_options = ['-l'] +# (Pdb) + +# q(uit) +# Quit from the debugger. +# The program being executed is aborted. + + +# Here's how it works. + +# Some changes were made to the interpreter: +# - if sys.trace is defined (by the user), it should be a function +# - sys.trace is called the global trace function +# - there can also a local trace function (see later) + +# Trace functions have three arguments: (frame, event, arg) +# - frame is the current stack frame +# - event is a string: 'call', 'line', 'return' or 'exception' +# - arg is dependent on the event type +# A trace function should return a new trace function or None. +# Class methods are accepted (and most useful!) as trace methods. + +# The events have the following meaning: +# +# 'call': A function is called (or some other code block entered). +# The global trace function is called; +# arg is the argument list to the function; +# the return value specifies the local trace function. +# +# 'line': The interpreter is about to execute a new line of code +# (sometimes multiple line events on one line exist). +# The local trace function is called; arg in None; +# the return value specifies the new local trace function. +# +# 'return': A function (or other code block) is about to return. +# The local trace function is called; +# arg is the value that will be returned. +# The trace function's return value is ignored. +# +# 'exception': An exception has occurred. +# The local trace function is called if there is one, +# else the global trace function is called; +# arg is a triple (exception, value, traceback); +# the return value specifies the new local trace function +# +# Note that as an exception is propagated down the chain of callers, +# an 'exception' event is generated at each level. + +# A stack frame object has the following read-only attributes: +# f_code: the code object being executed +# f_lineno: the current line number (-1 for 'call' events) +# f_back: the stack frame of the caller, or None +# f_locals: dictionary containing local name bindings +# f_globals: dictionary containing global name bindings + +# A code object has the following read-only attributes: +# co_code: the code string +# co_names: the list of names used by the code +# co_consts: the list of (literal) constants used by the code +# co_filename: the filename from which the code was compiled + import string import sys @@ -26,31 +167,35 @@ class Cmd: def init(self): self.prompt = PROMPT self.identchars = IDENTCHARS + self.lastcmd = '' return self - def commandloop(self): - try: - self.innerloop() - except EOFError: - pass - def innerloop(self): - while 1: - line = string.strip(self.getline()) - self.execline(line) - def execline(self, line): + def cmdloop(self): + stop = None + while not stop: + try: + line = raw_input(self.prompt) + except EOFError: + line = 'EOF' + stop = self.onecmd(line) + return stop + def onecmd(self, line): + line = string.strip(line) + if not line: + line = self.lastcmd + print line + else: + self.lastcmd = line i, n = 0, len(line) while i < n and line[i] in self.identchars: i = i+1 cmd, arg = line[:i], string.strip(line[i:]) if cmd == '': - self.default(line) + return self.default(line) else: try: func = eval('self.do_' + cmd) except AttributeError: - self.default(line) - return - func(arg) - def getline(self): - return raw_input(self.prompt) + return self.default(line) + return func(arg) def default(self, line): print '*** Unknown syntax:', line def do_help(self, arg): @@ -74,8 +219,7 @@ class Cmd: # A specialization of Cmd for use by the debugger -PdbDone = 'PdbDone' # Exception used internally -PdbQuit = 'PdbQuit' # Exception to just give up +PdbQuit = 'pdb.PdbQuit' # Exception to give up class Pdb(Cmd): @@ -83,32 +227,32 @@ class Pdb(Cmd): self = Cmd.init(self) self.prompt = '(Pdb) ' self.reset() - self.breaks = {} return self def reset(self): - self.whatnext = '' + self.breaks = {} self.botframe = None + self.stopframe = None self.forget() def forget(self): - self.curframe = self.topframe = None - self.stack = [] - self.lineno = None + self.setup(None) def setup(self, frame): self.curframe = self.topframe = frame self.stack = [] self.lineno = None - self.stopframe = None - self.whatnext = '' def run(self, cmd): - if cmd[-1:] != '\n': cmd = cmd + '\n' + import __main__ + dict = __main__.__dict__ + self.runctx(cmd, dict, dict) + + def runctx(self, cmd, globals, locals): self.reset() sys.trace = self.dispatch try: - exec(cmd) + exec(cmd + '\n', globals, locals) except PdbQuit: pass finally: @@ -116,64 +260,75 @@ class Pdb(Cmd): del sys.trace self.reset() - def dispatch(self, frame, where, arg): - if self.whatnext == 'quit': - return + def dispatch(self, frame, event, arg): + if event == 'line': + return self.dispatch_line(frame) + if event == 'call': + return self.dispatch_call(frame, arg) + if event == 'return': + return self.dispatch_return(frame, arg) + if event == 'exception': + return self.dispatch_exception(frame, arg) + print '*** dispatch: unknown event type', `event` + return self.dispatch + + def dispatch_line(self, frame): + if self.stop_here(frame) or self.break_here(frame): + self.ask_user(frame) + return self.dispatch + + def dispatch_call(self, frame, arg): if self.botframe is None: self.botframe = frame - if where == 'exception': - if self.whatnext == 'continue' and \ - arg[0] is not KeyboardInterrupt: - return self.trace - stop = 1 - elif self.whatnext == 'continue': - stop = 0 - elif self.whatnext == 'next': - stop = (frame == self.stopframe) - else: - stop = 1 - if not stop: - # Check breakpoints only - filename = frame.f_code.co_filename - if not self.breaks.has_key(filename): - return self.dispatch - lineno = frame.f_lineno - if lineno not in self.breaks[filename]: - return self.dispatch - if where == 'call': - print 'call arguments:', arg - elif where == 'return': - print 'return value:', arg - elif where == 'exception': - print 'exception:', arg[:2] - elif where != 'line': - print 'unknown trace type:', `where` - self.setup(frame) - try: - self.whatnext = self.commandloop() - finally: - self.forget() - if self.whatnext == 'quit': - raise PdbQuit - if self.whatnext == 'next': - if where != 'return': - self.stopframe = frame - else: - self.whatnext = 'step' + return + if not (self.stop_here(frame) or self.break_anywhere(frame)): + return + frame.f_locals['__args__'] = arg + return self.dispatch + + def dispatch_return(self, frame, arg): + if self.stop_here(frame): + print '!!! return', `arg` + return + + def dispatch_exception(self, frame, arg): + if arg[0] is PdbQuit: return None + if self.stop_here(frame): + print '!!! exception', arg[0] + ':', `arg[1]` + self.ask_user(frame) return self.dispatch - def commandloop(self): + def stop_here(self, frame): + if self.stopframe is None: + return 1 + if frame is self.stopframe: + return 1 + while frame is not self.stopframe: + if frame is None: + return 1 + frame = frame.f_back + return 0 + + def break_here(self, frame): + if not self.breaks.has_key(frame.f_code.co_filename): + return 0 + if not frame.f_lineno in \ + self.breaks[frame.f_code.co_filename]: + return 0 + return 1 + + def break_anywhere(self, frame): + return self.breaks.has_key(frame.f_code.co_filename) + + def ask_user(self, frame): + self.setup(frame) self.printwhere(self.curframe) - try: - self.innerloop() - except EOFError: - self.do_next('') - except PdbDone, msg: - return msg + dummy = self.cmdloop() + self.forget() def default(self, line): if not line: - self.do_next('') + return self.do_next('') else: if line[0] == '!': line = line[1:] try: @@ -181,7 +336,7 @@ class Pdb(Cmd): self.curframe.f_globals, \ self.curframe.f_locals) except: - print '***', sys.exc_type + ':', + print '***', sys.exc_type + ':', print `sys.exc_value` do_h = Cmd.do_help @@ -211,8 +366,13 @@ class Pdb(Cmd): def do_clear(self, arg): if not arg: - self.breaks = {} - print 'All breaks cleared!' + try: + reply = raw_input('Clear all breaks? ') + except EOFError: + reply = 'no' + reply = string.lower(string.strip(reply)) + if reply in ('y', 'yes'): + self.breaks = {} return try: lineno = int(eval(arg)) @@ -222,52 +382,63 @@ class Pdb(Cmd): filename = self.curframe.f_code.co_filename try: self.breaks[filename].remove(lineno) - if self.breaks[filename] == []: - del self.breaks[filename] except (ValueError, KeyError): print '*** There is no break there!' return + if not self.breaks[filename]: + del self.breaks[filename] + do_cl = do_clear # 'c' is already an abbreviation for 'continue' def do_where(self, arg): self.printtb() do_w = do_where def do_up(self, arg): - if not self.stack: print '*** Top' + if self.curframe == self.botframe or \ + not self.curframe.f_back: print '*** Top' else: - self.curframe = self.stack[-1] + self.stack.append(self.curframe) + self.curframe = self.curframe.f_back self.lineno = None - del self.stack[-1] self.printwhere(self.curframe) do_u = do_up def do_down(self, arg): - if self.curframe == self.botframe or \ - not self.curframe.f_back: print '*** Bottom' + if not self.stack: print '*** Bottom' else: - self.stack.append(self.curframe) - self.curframe = self.curframe.f_back + self.curframe = self.stack[-1] self.lineno = None + del self.stack[-1] self.printwhere(self.curframe) do_d = do_down def do_step(self, arg): - raise PdbDone, 'step' + self.stopframe = None + return 1 do_s = do_step def do_next(self, arg): - raise PdbDone, 'next' + self.stopframe = self.curframe + return 1 do_n = do_next + def do_return(self, arg): + self.stopframe = self.curframe.f_back + return 1 + do_r = do_return + def do_continue(self, arg): - raise PdbDone, 'continue' + self.stopframe = self.botframe + return 1 do_c = do_cont = do_continue def do_quit(self, arg): - raise PdbDone, 'quit' + self.stopframe = self.botframe + raise PdbQuit do_q = do_quit def do_list(self, arg): + self.lastcmd = 'list' last = None if arg: try: @@ -313,6 +484,25 @@ class Pdb(Cmd): except KeyboardInterrupt: pass do_l = do_list + + def do_args(self, arg): + try: + value = eval('__args__', self.curframe.f_globals, \ + self.curframe.f_locals) + except: + print '***', sys.exc_type + ':', `sys.exc_value` + return + print `value` + do_a = do_args + + def do_p(self, arg): + try: + value = eval(arg, self.curframe.f_globals, \ + self.curframe.f_locals) + except: + print '***', sys.exc_type + ':', `sys.exc_value` + return + print `value` # Print a traceback starting at a given stack frame # Note that it is printed upside-down with respect @@ -378,7 +568,7 @@ def bar(a): def test(): linecache.checkcache() - Pdb().init().run('foo(12)') + Pdb().init().run('foo(12)\n') # --------------------- main --------------------- @@ -396,6 +586,9 @@ def main(): sys.exit(2) del sys.argv[0] sys.path.insert(0, head) - Pdb().init().run('import ' + tail[:-3]) + run('import ' + tail[:-3]) else: - Pdb().init().run('') + run('') + +def run(statement): + Pdb().init().run(statement) |