Moved documentation out to pdb.doc file.
Moved class Cmd out to module cmd.py. Rewrote implementation of stack trace to incorporate traceback objects.
This commit is contained in:
Guido van Rossum
parent
7c36ad7f44
commit
6fe08b0fe4
361
Lib/pdb.py
361
Lib/pdb.py
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@ -1,232 +1,19 @@
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# pdb.py -- finally, a Python debugger! See below for instructions.
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# pdb.py -- finally, a Python debugger!
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# See file pdb.doc for instructions.
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# To do:
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# - Keep a list of exceptions trapped (default only KeyboardInterrupt?)
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# - It should be possible to intercept KeyboardInterrupt completely
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# - Handle return events differently (how?)
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# - When stopping on an exception, show traceback stack
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# - Merge with tb (for post-mortem usage)
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# - Show stack traces upside-down (like dbx/gdb) ???
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# (actually, the current way is more natural given the directions
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# taken by the up/down commands)
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# To use the debugger in its simplest form:
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# >>> import pdb
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# >>> pdb.run('<a statement>')
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# The debugger's prompt is '(Pdb) '.
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# This will stop in the first function call in <a statement>.
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# The commands recognized by the debugger are listed below.
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# Most can be abbreviated as indicated; e.g., h(elp) means that
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# 'help' can be typed as 'h' or 'help'
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# (but not as 'he' or 'hel', nor as 'H' or 'Help' or 'HELP').
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# Optional arguments are enclosed in square brackets.
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# A blank line repeats the previous command literally.
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# (Except for 'list', where it lists the next 11 lines.)
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# Commands that the debugger does not recognized are assumed to
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# be Python statements and are executed in the context of the
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# program being debugged.
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# Python statements can also be prefixed with an exclamation point ('!').
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# This is a powerful way to inspect the program being debugged;
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# it is even possible to change variables.
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# When an exception occurs in such a statement, the exception name
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# is printed but the debugger's state is not changed.
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# The debugger is not directly programmable; but it is implemented
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# as a class from which you can derive your own debugger class,
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# so you can make as fancy as you like.
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# The debugger's commands are:
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# h(elp)
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# Without argument, print the list of available commands.
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# With a command name as argument, print help about that command
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# (this is currently not implemented).
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# w(here)
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# Print a stack trace, with the most recent frame at the bottom.
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# An arrow indicates the "current frame", which determines the
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# context of most commands.
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# d(own)
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# Move the current frame one level down in the stack trace
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# (to an older frame).
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# u(p)
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# Move the current frame one level up in the stack trace
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# (to a newer frame).
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# b(reak) [lineno]
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# With a line number argument, set a break there in the current file.
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# Without argument, list all breaks.
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# cl(ear) [lineno]
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# With a line number argument, clear that break in the current file.
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# Without argument, clear all breaks (but first ask confirmation).
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# s(tep)
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# Execute the current line, stop at the first possible occasion
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# (either in a function that is called or in the current function).
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# n(ext)
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# Continue execution until the next line in the current function
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# is reached or it returns.
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# r(eturn)
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# Continue execution until the current function returns.
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# c(ont(inue))
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# Continue execution, only stop when a breakpoint is encountered.
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# l(ist) [first [,last]]
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# List source code for the current file.
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# Without arguments, list 11 lines around the current line
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# or continue the previous listing.
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# With one argument, list 11 lines starting at that line.
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# With two arguments, list the given range;
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# if the second argument is less than the first, it is a count.
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# a(rgs)
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# Print the argument list of the current function.
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# p expression
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# Print the value of the expression.
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# (!) statement
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# Execute the (one-line) statement in the context of
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# the current stack frame.
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# The exclamation point can be omitted unless the first word
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# of the statement resembles a debugger command.
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# To assign to a global variable you must always prefix the
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# command with a 'global' command, e.g.:
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# (Pdb) global list_options; list_options = ['-l']
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# (Pdb)
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# q(uit)
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# Quit from the debugger.
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# The program being executed is aborted.
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# Here's how it works.
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# Some changes were made to the interpreter:
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# - if sys.trace is defined (by the user), it should be a function
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# - sys.trace is called the global trace function
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# - there can also a local trace function (see later)
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# Trace functions have three arguments: (frame, event, arg)
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# - frame is the current stack frame
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# - event is a string: 'call', 'line', 'return' or 'exception'
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# - arg is dependent on the event type
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# A trace function should return a new trace function or None.
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# Class methods are accepted (and most useful!) as trace methods.
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# The events have the following meaning:
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#
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# 'call': A function is called (or some other code block entered).
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# The global trace function is called;
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# arg is the argument list to the function;
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# the return value specifies the local trace function.
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#
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# 'line': The interpreter is about to execute a new line of code
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# (sometimes multiple line events on one line exist).
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# The local trace function is called; arg in None;
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# the return value specifies the new local trace function.
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#
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# 'return': A function (or other code block) is about to return.
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# The local trace function is called;
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# arg is the value that will be returned.
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# The trace function's return value is ignored.
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#
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# 'exception': An exception has occurred.
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# The local trace function is called if there is one,
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# else the global trace function is called;
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# arg is a triple (exception, value, traceback);
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# the return value specifies the new local trace function
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#
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# Note that as an exception is propagated down the chain of callers,
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# an 'exception' event is generated at each level.
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# A stack frame object has the following read-only attributes:
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# f_code: the code object being executed
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# f_lineno: the current line number (-1 for 'call' events)
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# f_back: the stack frame of the caller, or None
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# f_locals: dictionary containing local name bindings
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# f_globals: dictionary containing global name bindings
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# A code object has the following read-only attributes:
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# co_code: the code string
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# co_names: the list of names used by the code
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# co_consts: the list of (literal) constants used by the code
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# co_filename: the filename from which the code was compiled
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# - It should be possible to intercept KeyboardInterrupt
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# - Handle return events differently -- always printing the r.v. can be bad!
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# - Merge with tb, to get a single debugger for active and post-mortem usage
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# - Solve bugs in termination (e.g., 'continue' after the program
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# is done proceeds to debug the debugger; 'quit' sometimes complains
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# about the PdbQuit exception...)
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import string
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import sys
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import linecache
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# A generic class to build command interpreters
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PROMPT = '(Cmd) '
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IDENTCHARS = string.letters + string.digits + '_'
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class Cmd:
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def init(self):
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self.prompt = PROMPT
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self.identchars = IDENTCHARS
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self.lastcmd = ''
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return self
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def cmdloop(self):
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stop = None
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while not stop:
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try:
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line = raw_input(self.prompt)
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except EOFError:
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line = 'EOF'
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stop = self.onecmd(line)
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return stop
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def onecmd(self, line):
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line = string.strip(line)
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if not line:
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line = self.lastcmd
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print line
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else:
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self.lastcmd = line
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i, n = 0, len(line)
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while i < n and line[i] in self.identchars: i = i+1
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cmd, arg = line[:i], string.strip(line[i:])
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if cmd == '':
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return self.default(line)
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else:
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try:
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func = eval('self.do_' + cmd)
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except AttributeError:
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return self.default(line)
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return func(arg)
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def default(self, line):
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print '*** Unknown syntax:', line
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def do_help(self, arg):
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if arg:
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# XXX check arg syntax
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try:
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func = eval('self.help_' + arg)
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except:
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print '*** No help on', `arg`
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return
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func()
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else:
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import getattr
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names = getattr.dir(self)
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cmds = []
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for name in names:
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if name[:3] == 'do_':
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cmds.append(name[3:])
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print cmds
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from cmd import Cmd
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# A specialization of Cmd for use by the debugger
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@ -242,18 +29,32 @@ class Pdb(Cmd):
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return self
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def reset(self):
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self.quitting = 0
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self.breaks = {}
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self.botframe = None
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self.stopframe = None
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self.forget()
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def forget(self):
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self.setup(None)
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self.setup(None, None)
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def setup(self, frame):
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self.curframe = self.topframe = frame
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self.stack = []
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def setup(self, f, t):
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self.lineno = None
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self.stack = []
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if t and t.tb_frame is f:
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t = t.tb_next
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while f and f is not self.botframe:
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self.stack.append((f, f.f_lineno))
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f = f.f_back
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self.stack.reverse()
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self.curindex = max(0, len(self.stack) - 1)
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while t:
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self.stack.append((t.tb_frame, t.tb_lineno))
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t = t.tb_next
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if 0 <= self.curindex < len(self.stack):
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self.curframe = self.stack[self.curindex][0]
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else:
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self.curframe = None
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def run(self, cmd):
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import __main__
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@ -267,12 +68,21 @@ class Pdb(Cmd):
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exec(cmd + '\n', globals, locals)
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except PdbQuit:
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pass
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finally:
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except:
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print '***', sys.exc_type + ':', `sys.exc_value`
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print '*** Post Mortem Debugging:'
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sys.trace = None
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del sys.trace
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try:
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self.ask_user(None, sys.exc_traceback)
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except PdbQuit:
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pass
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finally:
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self.reset()
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def dispatch(self, frame, event, arg):
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if self.quitting:
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return None
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if event == 'line':
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return self.dispatch_line(frame)
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if event == 'call':
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@ -286,7 +96,7 @@ class Pdb(Cmd):
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def dispatch_line(self, frame):
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if self.stop_here(frame) or self.break_here(frame):
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self.ask_user(frame)
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self.ask_user(frame, None)
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return self.dispatch
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def dispatch_call(self, frame, arg):
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@ -304,10 +114,9 @@ class Pdb(Cmd):
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return
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def dispatch_exception(self, frame, arg):
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if arg[0] is PdbQuit: return None
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if self.stop_here(frame):
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print '!!! exception', arg[0] + ':', `arg[1]`
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self.ask_user(frame)
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self.ask_user(frame, arg[2])
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return self.dispatch
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def stop_here(self, frame):
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@ -315,8 +124,8 @@ class Pdb(Cmd):
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return 1
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if frame is self.stopframe:
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return 1
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while frame is not self.stopframe:
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if frame is None:
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while frame is not None and frame is not self.stopframe:
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if frame is self.botframe:
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return 1
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frame = frame.f_back
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return 0
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@ -332,10 +141,10 @@ class Pdb(Cmd):
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def break_anywhere(self, frame):
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return self.breaks.has_key(frame.f_code.co_filename)
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def ask_user(self, frame):
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self.setup(frame)
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self.printwhere(self.curframe)
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dummy = self.cmdloop()
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def ask_user(self, frame, traceback):
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self.setup(frame, traceback)
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self.printframelineno(self.stack[self.curindex])
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self.cmdloop()
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self.forget()
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def default(self, line):
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@ -402,26 +211,25 @@ class Pdb(Cmd):
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do_cl = do_clear # 'c' is already an abbreviation for 'continue'
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def do_where(self, arg):
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self.printtb()
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self.printstacktrace()
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do_w = do_where
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def do_up(self, arg):
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if self.curframe == self.botframe or \
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not self.curframe.f_back: print '*** Top'
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if self.curindex == 0:
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print '*** Oldest frame'
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else:
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self.stack.append(self.curframe)
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self.curframe = self.curframe.f_back
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self.lineno = None
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self.printwhere(self.curframe)
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self.curindex = self.curindex - 1
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self.curframe = self.stack[self.curindex][0]
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self.printframelineno(self.stack[self.curindex])
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do_u = do_up
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def do_down(self, arg):
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if not self.stack: print '*** Bottom'
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if self.curindex + 1 == len(self.stack):
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print '*** Newest frame'
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else:
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self.curframe = self.stack[-1]
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self.lineno = None
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del self.stack[-1]
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self.printwhere(self.curframe)
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self.curindex = self.curindex + 1
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self.curframe = self.stack[self.curindex][0]
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self.printframelineno(self.stack[self.curindex])
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do_d = do_down
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def do_step(self, arg):
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do_c = do_cont = do_continue
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def do_quit(self, arg):
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self.stopframe = self.botframe
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self.quitting = 1
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sys.trace = None; del sys.trace
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raise PdbQuit
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do_q = do_quit
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@ -516,36 +325,39 @@ class Pdb(Cmd):
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return
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print `value`
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# Print a traceback starting at a given stack frame
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# Note that it is printed upside-down with respect
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# to the orientation suggested by the up/down commands.
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# This is consistent with gdb.
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def printtb(self):
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list = []
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frame = self.topframe
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while frame:
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list.append(frame)
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if frame is self.botframe: break
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frame = frame.f_back
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list.reverse()
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for frame in list:
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self.printwhere(frame)
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# Print a traceback starting at the top stack frame.
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# Note that the most recently entered frame is printed last;
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# this is different from dbx and gdb, but consistent with
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# the Python interpreter's stack trace.
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# It is also consistent with the up/down commands (which are
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# compatible with dbx and gdb: up moves towards 'main()'
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# and down moves towards the most recent stack frame).
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def printwhere(self, frame):
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def printstacktrace(self):
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for x in self.stack:
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self.printframelineno(x)
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def printframelineno(self, (frame, lineno)):
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if frame is self.curframe: print '->',
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code = frame.f_code
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filename = code.co_filename
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lineno = frame.f_lineno
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print filename + '(' + `lineno` + ')',
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line = linecache.getline(filename, lineno)
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if line: print string.strip(line),
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print string.strip(line),
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print
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def run(statement):
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Pdb().init().run(statement)
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def runctx(statement, globals, locals):
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Pdb().init().runctx(statement, globals, locals)
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# --------------------- testing ---------------------
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# The Ackermann function -- a highly recursive beast
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cheat = 0
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cheat = 2
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cache = {}
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def ack(x, y):
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key = `(long(x), long(y))`
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@ -572,15 +384,21 @@ def foo(n):
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print 'foo', n
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x = bar(n*2)
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print 'bar returned', x
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return
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y = ack(4, 3)
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return y
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def bar(a):
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print 'bar', a
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return a*10
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def melt(n):
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print 1.0/n
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melt(n-1)
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def test():
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linecache.checkcache()
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Pdb().init().run('foo(12)\n')
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runctx('from pdb import foo; foo(12)', {}, {})
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runctx('from pdb import melt; melt(5)', {}, {})
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# --------------------- main ---------------------
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@ -600,7 +418,4 @@ def main():
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sys.path.insert(0, head)
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run('import ' + tail[:-3])
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else:
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run('')
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def run(statement):
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Pdb().init().run(statement)
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run(raw_input('Python statement to debug: '))
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||||
|
|
|
|||
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Reference in New Issue