Chương trình debug python
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The module The debugger is extensible – it is actually defined as the class python3 -m pdb myscript.py0. This is currently undocumented but easily understood by reading the source. The extension interface uses the modules python3 -m pdb myscript.py1 and python3 -m pdb myscript.py2. The debugger’s prompt is python3 -m pdb myscript.py3. Typical usage to run a program under control of the debugger is: >>> import pdb >>> import mymodule >>> pdb.run('mymodule.test()') > Changed in version 3.3: Tab-completion via the python3 -m pdb myscript.py4 module is available for commands and command arguments, e.g. the current global and local names are offered as arguments of the python3 -m pdb myscript.py5 command. python3 -m pdb myscript.py6 can also be invoked as a script to debug other scripts. For example: python3 -m pdb myscript.py When invoked as a script, pdb will automatically enter post-mortem debugging if the program being debugged exits abnormally. After post-mortem debugging (or after normal exit of the program), pdb will restart the program. Automatic restarting preserves pdb’s state (such as breakpoints) and in most cases is more useful than quitting the debugger upon program’s exit. New in version 3.2: python3 -m pdb myscript.py6 now accepts a python3 -m pdb myscript.py8 option that executes commands as if given in a python3 -m pdb myscript.py9 file, see Debugger Commands. New in version 3.7: python3 -m pdb myscript.py6 now accepts a import pdb; pdb.set_trace()1 option that execute modules similar to the way import pdb; pdb.set_trace()2 does. As with a script, the debugger will pause execution just before the first line of the module. The typical usage to break into the debugger is to insert: import pdb; pdb.set_trace() at the location you want to break into the debugger, and then run the program. You can then step through the code following this statement, and continue running without the debugger using the import pdb; pdb.set_trace()3 command. New in version 3.7: The built-in import pdb; pdb.set_trace()4, when called with defaults, can be used instead of import pdb; pdb.set_trace()5. The typical usage to inspect a crashed program is: >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File " The module defines the following functions; each enters the debugger in a slightly different way: pdb.run(statement, globals=None, locals=None)¶Execute the statement (given as a string or a code object) under debugger control. The debugger prompt appears before any code is executed; you can set breakpoints and type import pdb; pdb.set_trace()3, or you can step through the statement using import pdb; pdb.set_trace()7 or import pdb; pdb.set_trace()8 (all these commands are explained below). The optional globals and locals arguments specify the environment in which the code is executed; by default the dictionary of the module import pdb; pdb.set_trace()9 is used. (See the explanation of the built-in >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "0 or >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "1 functions.)pdb.runeval(expression, globals=None, locals=None)¶ Evaluate the expression (given as a string or a code object) under debugger control. When >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "2 returns, it returns the value of the expression. Otherwise this function is similar to >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "3.pdb.runcall(function, *args, **kwds)¶ Call the function (a function or method object, not a string) with the given arguments. When >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "4 returns, it returns whatever the function call returned. The debugger prompt appears as soon as the function is entered.pdb.set_trace(*, header=None)¶ Enter the debugger at the calling stack frame. This is useful to hard-code a breakpoint at a given point in a program, even if the code is not otherwise being debugged (e.g. when an assertion fails). If given, header is printed to the console just before debugging begins. Changed in version 3.7: The keyword-only argument header. pdb.post_mortem(traceback=None)¶Enter post-mortem debugging of the given traceback object. If no traceback is given, it uses the one of the exception that is currently being handled (an exception must be being handled if the default is to be used). pdb.pm()¶Enter post-mortem debugging of the traceback found in >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "5. The >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "6 functions and >>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "7 are aliases for instantiating the python3 -m pdb myscript.py0 class and calling the method of the same name. If you want to access further features, you have to do this yourself:class pdb.Pdb(completekey='tab', stdin=None, stdout=None, skip=None, nosigint=False, readrc=True)¶ python3 -m pdb myscript.py0 is the debugger class. The completekey, stdin and stdout arguments are passed to the underlying import pdb; pdb.Pdb(skip=['django.*']).set_trace()0 class; see the description there. 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. 1 By default, Pdb sets a handler for the SIGINT signal (which is sent when the user presses Ctrl-C on the console) when you give a import pdb; pdb.set_trace()3 command. This allows you to break into the debugger again by pressing Ctrl-C. If you want Pdb not to touch the SIGINT handler, set nosigint to true. The readrc argument defaults to true and controls whether Pdb will load .pdbrc files from the filesystem. Example call to enable tracing with skip: import pdb; pdb.Pdb(skip=['django.*']).set_trace() Raises an auditing event import pdb; pdb.Pdb(skip=['django.*']).set_trace()2 with no arguments. New in version 3.1: The skip argument. New in version 3.2: The nosigint argument. Previously, a SIGINT handler was never set by Pdb. Changed in version 3.6: The readrc argument. run(statement, globals=None, locals=None)¶runeval(expression, globals=None, locals=None)¶runcall(function, *args, **kwds)¶set_trace()¶See the documentation for the functions explained above. Debugger Commands¶The commands recognized by the debugger are listed below. Most commands can be abbreviated to one or two letters as indicated; e.g. import pdb; pdb.Pdb(skip=['django.*']).set_trace()3 means that either import pdb; pdb.Pdb(skip=['django.*']).set_trace()4 or import pdb; pdb.Pdb(skip=['django.*']).set_trace()5 can be used to enter the help command (but not import pdb; pdb.Pdb(skip=['django.*']).set_trace()6 or import pdb; pdb.Pdb(skip=['django.*']).set_trace()7, nor import pdb; pdb.Pdb(skip=['django.*']).set_trace()8 or import pdb; pdb.Pdb(skip=['django.*']).set_trace()9 or (Pdb) commands 1 (com) p some_variable (com) end (Pdb)0). Arguments to commands must be separated by whitespace (spaces or tabs). Optional arguments are enclosed in square brackets ( (Pdb) commands 1 (com) p some_variable (com) end (Pdb)1) in the command syntax; the square brackets must not be typed. Alternatives in the command syntax are separated by a vertical bar ( (Pdb) commands 1 (com) p some_variable (com) end (Pdb)2). Entering a blank line repeats the last command entered. Exception: if the last command was a (Pdb) commands 1 (com) p some_variable (com) end (Pdb)3 command, the next 11 lines are listed. Commands that the debugger doesn’t recognize 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 ( (Pdb) commands 1 (com) p some_variable (com) end (Pdb)4). This is a powerful way to inspect the program being debugged; it is even possible to change a variable or call a function. When an exception occurs in such a statement, the exception name is printed but the debugger’s state is not changed. The debugger supports aliases. Aliases can have parameters which allows one a certain level of adaptability to the context under examination. Multiple commands may be entered on a single line, separated by (Pdb) commands 1 (com) p some_variable (com) end (Pdb)5. (A single (Pdb) commands 1 (com) p some_variable (com) end (Pdb)6 is not used as it is the separator for multiple commands in a line that is passed to the Python parser.) No intelligence is applied to separating the commands; the input is split at the first (Pdb) commands 1 (com) p some_variable (com) end (Pdb)5 pair, even if it is in the middle of a quoted string. A workaround for strings with double semicolons is to use implicit string concatenation (Pdb) commands 1 (com) p some_variable (com) end (Pdb)8 or (Pdb) commands 1 (com) p some_variable (com) end (Pdb)9. If a file python3 -m pdb myscript.py9 exists in the user’s home directory or in the current directory, it is read with # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi self1 encoding and executed as if it had been typed at the debugger prompt. This is particularly useful for aliases. If both files exist, the one in the home directory is read first and aliases defined there can be overridden by the local file. Changed in version 3.11: python3 -m pdb myscript.py9 is now read with # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi self1 encoding. Previously, it was read with the system locale encoding. Changed in version 3.2: python3 -m pdb myscript.py9 can now contain commands that continue debugging, such as import pdb; pdb.set_trace()3 or import pdb; pdb.set_trace()8. Previously, these commands had no effect.h(elp) [command]¶ Without argument, print the list of available commands. With a command as argument, print help about that command. # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi self7 displays the full documentation (the docstring of the pdb module). Since the command argument must be an identifier, # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi self9 must be entered to get help on the (Pdb) commands 1 (com) p some_variable (com) end (Pdb)4 command.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) [count]¶Move the current frame count (default one) levels down in the stack trace (to a newer frame). u(p) [count]¶Move the current frame count (default one) levels up in the stack trace (to an older frame). b(reak) [([filename:]lineno | function) [, condition]]¶With a lineno argument, set a break there in the current file. With a function argument, set a break at the first executable statement within that function. The line number may be prefixed with a filename and a colon, to specify a breakpoint in another file (probably one that hasn’t been loaded yet). The file is searched on (Pdb) global list_options; list_options = ['-l'] (Pdb)1. Note that each breakpoint is assigned a number to which all the other breakpoint commands refer. If a second argument is present, it is an expression which must evaluate to true before the breakpoint is honored. Without argument, list all breaks, including for each breakpoint, the number of times that breakpoint has been hit, the current ignore count, and the associated condition if any. tbreak [([filename:]lineno | function) [, condition]]¶Temporary breakpoint, which is removed automatically when it is first hit. The arguments are the same as for (Pdb) global list_options; list_options = ['-l'] (Pdb)2.cl(ear) [filename:lineno | bpnumber ...]¶ With a filename:lineno argument, clear all the breakpoints at this line. With a space separated list of breakpoint numbers, clear those breakpoints. Without argument, clear all breaks (but first ask confirmation). disable [bpnumber ...]¶Disable the breakpoints given as a space separated list of breakpoint numbers. Disabling a breakpoint means it cannot cause the program to stop execution, but unlike clearing a breakpoint, it remains in the list of breakpoints and can be (re-)enabled. enable [bpnumber ...]¶Enable the breakpoints specified. ignore bpnumber [count]¶Set the ignore count for the given breakpoint number. If count is omitted, the ignore count is set to 0. A breakpoint becomes active when the ignore count is zero. When non-zero, the count is decremented each time the breakpoint is reached and the breakpoint is not disabled and any associated condition evaluates to true. condition bpnumber [condition]¶Set a new condition for the breakpoint, an expression which must evaluate to true before the breakpoint is honored. If condition is absent, any existing condition is removed; i.e., the breakpoint is made unconditional. commands [bpnumber]¶Specify a list of commands for breakpoint number bpnumber. The commands themselves appear on the following lines. Type a line containing just (Pdb) global list_options; list_options = ['-l'] (Pdb)3 to terminate the commands. An example: (Pdb) commands 1 (com) p some_variable (com) end (Pdb) To remove all commands from a breakpoint, type (Pdb) global list_options; list_options = ['-l'] (Pdb)4 and follow it immediately with (Pdb) global list_options; list_options = ['-l'] (Pdb)3; that is, give no commands. With no bpnumber argument, (Pdb) global list_options; list_options = ['-l'] (Pdb)4 refers to the last breakpoint set. You can use breakpoint commands to start your program up again. Simply use the import pdb; pdb.set_trace()3 command, or import pdb; pdb.set_trace()7, or any other command that resumes execution. Specifying any command resuming execution (currently import pdb; pdb.set_trace()3, import pdb; pdb.set_trace()7, import pdb; pdb.set_trace()8, pdb 2, pdb 3, pdb 4 and their abbreviations) terminates the command list (as if that command was immediately followed by end). This is because any time you resume execution (even with a simple next or step), you may encounter another breakpoint—which could have its own command list, leading to ambiguities about which list to execute.If you use the ‘silent’ command in the command list, the usual message about stopping at a breakpoint is not printed. This may be desirable for breakpoints that are to print a specific message and then continue. If none of the other commands print anything, you see no sign that the breakpoint was reached. s(tep)¶Execute the current line, stop at the first possible occasion (either in a function that is called or on the next line in the current function). n(ext)¶Continue execution until the next line in the current function is reached or it returns. (The difference between import pdb; pdb.set_trace()8 and import pdb; pdb.set_trace()7 is that import pdb; pdb.set_trace()7 stops inside a called function, while import pdb; pdb.set_trace()8 executes called functions at (nearly) full speed, only stopping at the next line in the current function.)unt(il) [lineno]¶ Without argument, continue execution until the line with a number greater than the current one is reached. With a line number, continue execution until a line with a number greater or equal to that is reached. In both cases, also stop when the current frame returns. Changed in version 3.2: Allow giving an explicit line number. r(eturn)¶Continue execution until the current function returns. Continue execution, only stop when a breakpoint is encountered. j(ump) lineno¶Set the next line that will be executed. Only available in the bottom-most frame. This lets you jump back and execute code again, or jump forward to skip code that you don’t want to run. It should be noted that not all jumps are allowed – for instance it is not possible to jump into the middle of a List source code for the current file. Without arguments, list 11 lines around the current line or continue the previous listing. With The current line in the current frame is indicated by New in version 3.2: The List all source code for the current function or frame. Interesting lines are marked as for (Pdb) commands 1 (com) p some_variable (com) end (Pdb)3. New in version 3.2. a(rgs)¶Print the argument list of the current function. p expression¶Evaluate the expression in the current context and print its value. Note
Like the python3 -m pdb myscript.py5 command, except the value of the expression is pretty-printed using the pdb 9 module.whatis expression¶Print the type of the expression. source expression¶Try to get source code for the given object and display it. New in version 3.2. display [expression]¶Display the value of the expression if it changed, each time execution stops in the current frame. Without expression, list all display expressions for the current frame. New in version 3.2. undisplay [expression]¶Do not display the expression any more in the current frame. Without expression, clear all display expressions for the current frame. New in version 3.2. interact¶Start an interactive interpreter (using the python3 -m pdb myscript.py00 module) whose global namespace contains all the (global and local) names found in the current scope. New in version 3.2. alias [name [command]]¶Create an alias called name that executes command. The command must not be enclosed in quotes. Replaceable parameters can be indicated by python3 -m pdb myscript.py01, python3 -m pdb myscript.py02, and so on, while python3 -m pdb myscript.py03 is replaced by all the parameters. If no command is given, the current alias for name is shown. If no arguments are given, all aliases are listed. Aliases may be nested and can contain anything that can be legally typed at the pdb prompt. Note that internal pdb commands can be overridden by aliases. Such a command is then hidden until the alias is removed. Aliasing is recursively applied to the first word of the command line; all other words in the line are left alone. As an example, here are two useful aliases (especially when placed in the python3 -m pdb myscript.py9 file): # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi selfunalias name¶ Delete the specified alias. ! 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 set a global variable, you can prefix the assignment command with a python3 -m pdb myscript.py05 statement on the same line, e.g.: (Pdb) global list_options; list_options = ['-l'] (Pdb)run [args ...]¶restart [args ...]¶ Restart the debugged Python program. If an argument is supplied, it is split with python3 -m pdb myscript.py06 and the result is used as the new python3 -m pdb myscript.py07. History, breakpoints, actions and debugger options are preserved. python3 -m pdb myscript.py08 is an alias for python3 -m pdb myscript.py09.q(uit)¶ Quit from the debugger. The program being executed is aborted. debug code¶Enter a recursive debugger that steps through the code argument (which is an arbitrary expression or statement to be executed in the current environment). retval¶Print the return value for the last return of a function. Footnotes 1Whether a frame is considered to originate in a certain module is determined by the python3 -m pdb myscript.py10 in the frame globals. |