Python Module_pdb_DEBUG 方法

目录

• 目录
• pdb
  • pdb 的 Debug 方式
  • pdb 的调试指令
• 示例
• IPython 自带的 Debug 工具 ipdb

pdb

pdb 是 Python 自带的程序包，为 Python 程序提供了一种可交互的源码调试功能。主要特性包括：

• 设置断点
• 单步调试
• 进入函数调试
• 查看当前代码
• 查看栈片段
• 动态修改变量值

pdb 的 Debug 方式

• pdb 可以在源码内直接使用，相当于打断点，import pdb 后，在需要调试的代码处添加写入 pdb.set_trace() 语句即可。

def pushit():

    import pdb
    pdb.set_trace()

    stack.append(raw_input('Enter New String: ').strip())

• 通过命令行参数的形式来进行调试，EG.

python -m pdb stack_demo.py

• 在 Python 交互环境中调试

>>> import pdb
>>> import mymodule
>>> pdb.run(‘mymodule.test()’)

pdb 的调试指令

指令	解析
break [codeline] 或 b [codeline]	在 codeline 行处，设置断点
condition codeline [condition]	设置条件断点
disable [codeline]	使某一行断点失效
enable [codeline]	使某一行的断点生效
clear [codeline] 或 cl [codeline]	就是清除指定的断点,不带参数就是清除所有的断点
continue 或 c	继续执行程序
list 或 l	查看当前行上下文的代码段
next 或 n	执行下一行，但跳过函数
step 或 s	执行下一行，并进入被调用的函数
j [codeline]	跳转到前面的 codeline 行
w	打印当前执行点的位置
return 或 r	执行代码直到从当前函数返回
p	打印一个变量或参数的值
a	打印当前函数及参数的值
!	感叹号后面跟着语句，可以直接改变某个变量值
exit 或 q	中止并退出
help [command] 或 h [command]	commands 的帮助手册

示例

stack_demo.py : 一个 Python 实现的 栈 数据结构

stack = []

def pushit():

    #import pdb
    #pdb.set_trace()

    stack.append(raw_input('Enter New String: ').strip())

def popit():
    if len(stack) == 0:
        print "Cannot pop from an empty stack!"
    else:
        print 'Remove [', `stack.pop()`, ']'

def viewstack():
        print stack

CMDs = {'u':pushit, 'o':popit, 'v':viewstack}

def showmenu():
    pr = """
    p(U)sh
    p(O)p
    (V)iew
    (Q)uit

    Enter choice: """

    while True:
        while True:
            try:
                choice = raw_input(pr).strip()[0].lower()
            except (EOFError, KeyboardInterrupt, IndexError):
                choice = 'q'

            print '\nYou picked: [%s]' % choice
            if choice not in 'uovq':
                print 'Invalid option, try again'
            else:
                break

        if choice == 'q':
            break
        CMDs[choice]()

if __name__ == '__main__':
    showmenu()

通过命令行参数的形式来进行调试

In [2]: !python -m pdb stack_demo.py
> d:\development\python27\workspace\stack_demo.py(1)<module>()
-> stack = []            # 这种方式会从第一条语句开始进入调试
(Pdb) b 7                # 空白行或注释不能打断点
*** Blank or comment
(Pdb) b 8                # 在 codeline == 8 处打上断点
Breakpoint 1 at d:\development\python27\workspace\stack_demo.py:8
(Pdb) n                  # 下一行
> d:\development\python27\workspace\stack_demo.py(3)<module>()
-> def pushit():
(Pdb) n                  # 下一行，并且跳过函数内的语句
> d:\development\python27\workspace\stack_demo.py(10)<module>()
-> def popit():
(Pdb) l                  # 列出下面的代码
  3     def pushit():
  4
  5         #import pdb
  6         #pdb.set_trace()
  7
  8 B->     stack.append(raw_input('Enter New String: ').strip())
  9
 10     def popit():
 11         if len(stack) == 0:
 12             print "Cannot pop from an empty stack!"
 13         else:
(Pdb) n
Enter New String: 'jmilkfan'
--Return--
> d:\development\python27\workspace\stack_demo.py(8)pushit()->None
-> stack.append(raw_input('Enter New String: ').strip())
(Pdb) w                  # 打印当前位置
  d:\development\python27\lib\bdb.py(400)run()
-> exec cmd in globals, locals
  <string>(1)<module>()
  d:\development\python27\workspace\stack_demo.py(49)<module>()
-> showmenu()
  d:\development\python27\workspace\stack_demo.py(46)showmenu()
-> CMDs[choice]()
> d:\development\python27\workspace\stack_demo.py(8)pushit()->None
-> stack.append(raw_input('Enter New String: ').strip())
(Pdb) p stack                  # 输出一个变量的值
["'jmilkfan'"]
(Pdb) !stack = ["fanguiju"]    # 改变一个变量的值
(Pdb) p stack
['fanguiju']
(Pdb) c                        # 继续往下执行

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: q

You picked: [q]
The program finished and will be restarted
> d:\development\python27\workspace\stack_demo.py(1)<module>()
-> stack = []
(Pdb) q                       # 退出调试

• 在源码内直接使用

In [8]: run stack_demo.py

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: u

You picked: [u]
> d:\development\python27\workspace\stack_demo.py(8)pushit()
-> stack.append(raw_input('Enter New String: ').strip())    # 开始进入调试，该语句的前一条语句为 pdb.set_trace()
(Pdb) l
  3     def pushit():
  4
  5         import pdb
  6         pdb.set_trace()
  7
  8  ->     stack.append(raw_input('Enter New String: ').strip())
  9
 10     def popit():
 11         if len(stack) == 0:
 12             print "Cannot pop from an empty stack!"
 13         else:
(Pdb) j 16            # 不能跳转到还没有执行过的代码行
*** Jump failed: line 16 comes after the current code block
(Pdb) j 3
> d:\development\python27\workspace\stack_demo.py(3)pushit()
-> def pushit():
(Pdb) s              # 进入一个函数内部
> d:\development\python27\workspace\stack_demo.py(6)pushit()
-> pdb.set_trace()
(Pdb) s              # 还可以进入到调用函数的内部
--Call--
> d:\development\python27\lib\pdb.py(1250)set_trace()
-> def set_trace():
(Pdb) c              # 继续执行代码
> d:\development\python27\workspace\stack_demo.py(8)pushit()
-> stack.append(raw_input('Enter New String: ').strip())
(Pdb) r              # 执行代码直到从当前函数返回
Enter New String: 'jmilkfan'
--Return--
> d:\development\python27\workspace\stack_demo.py(8)pushit()->None
-> stack.append(raw_input('Enter New String: ').strip())
(Pdb) l
 25             (V)iew
 26             (Q)uit
 27
 28             Enter choice: """
 29
 30  ->     while True:
 31             while True:
 32                 try:
 33                     choice = raw_input(pr).strip()[0].lower()
 34                 except (EOFError, KeyboardInterrupt, IndexError):
 35                     choice = 'q'
(Pdb) c

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: u

You picked: [u]
> d:\development\python27\workspace\stack_demo.py(8)pushit()
-> stack.append(raw_input('Enter New String: ').strip())
(Pdb) s
--Call--
> d:\development\python27\lib\site-packages\win_unicode_console\raw_input.py(71)raw_input()
-> def raw_input(prompt=""):
(Pdb) p pr
'\n\tp(U)sh\n\tp(O)p\n\t(V)iew\n\t(Q)uit\n\t\n\tEnter choice: '
(Pdb) n

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: v
> d:\development\python27\workspace\stack_demo.py(37)showmenu()
-> print '\nYou picked: [%s]' % choice
(Pdb) n

You picked: [v]
> d:\development\python27\workspace\stack_demo.py(38)showmenu()
-> if choice not in 'uovq':
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(41)showmenu()
-> break
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(44)showmenu()
-> if choice == 'q':
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(46)showmenu()
-> CMDs[choice]()
(Pdb) n
[u"'jmilkfan'", u"'fanguiju'", u"'fanguiju'"]
> d:\development\python27\workspace\stack_demo.py(30)showmenu()
-> while True:
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(31)showmenu()
-> while True:
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(32)showmenu()
-> try:
(Pdb) n
> d:\development\python27\workspace\stack_demo.py(33)showmenu()
-> choice = raw_input(pr).strip()[0].lower()
(Pdb) n

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: v
> d:\development\python27\workspace\stack_demo.py(37)showmenu()
-> print '\nYou picked: [%s]' % choice
(Pdb) c

You picked: [v]
[u"'jmilkfan'", u"'fanguiju'", u"'fanguiju'"]

        p(U)sh
        p(O)p
        (V)iew
        (Q)uit

        Enter choice: 0

IPython 自带的 Debug 工具 ipdb

基本用法跟 pdb 一样，优点在于很 IPython 结合使用能更方便的完成一个功能，也更加清晰。

In [1]: run -d stack_demo.py
Breakpoint 1 at d:\development\python27\workspace\stack_demo.py:1
NOTE: Enter 'c' at the ipdb>  prompt to continue execution.
> d:\development\python27\workspace\stack_demo.py(1)<module>()
1---> 1 stack = []
      2
      3 def pushit():
      4
      5     stack.append(raw_input('Enter New String: ').strip())

ipdb> h

Documented commands (type help <topic>):
========================================
EOF    bt         cont      enable  jump  pdef    psource  run      unt
a      c          continue  exit    l     pdoc    q        s        until
alias  cl         d         h       list  pfile   quit     step     up
args   clear      debug     help    n     pinfo   r        tbreak   w
b      commands   disable   ignore  next  pinfo2  restart  u        whatis
break  condition  down      j       p     pp      return   unalias  where

Miscellaneous help topics:
==========================
exec  pdb

Undocumented commands:
======================
ll  longlist  retval  rv

ipdb>