Python 调试记录笔记

on Others, Python

Try

try:
    print 'try...'
    r = 10 / int('a')
    print 'result:', r
except ValueError, e:
    print 'ValueError:', e
except ZeroDivisionError, e:
    print 'ZeroDivisionError:', e
else:
    print 'no error!'
finally:
    print 'finally...'
print 'END'

assert

# err.py
def foo(s):
    n = int(s)
    assert n != 0, 'n is zero!'
    return 10 / n

def main():
    foo('0')

pdb

# err.py
s = '0'
n = int(s)
print 10 / n

启动

$ python -m pdb err.py
> /Users/michael/Github/sicp/err.py(2)<module>()
-> s = '0'

以参数-m pdb启动后，pdb定位到下一步要执行的代码-> s = '0'。输入命令l来查看代码：

(Pdb) l
  1     # err.py
  2  -> s = '0'
  3     n = int(s)
  4     print 10 / n
[EOF]

输入命令n可以单步执行代码：

(Pdb) n
> /Users/michael/Github/sicp/err.py(3)<module>()
-> n = int(s)
(Pdb) n
> /Users/michael/Github/sicp/err.py(4)<module>()
-> print 10 / n

任何时候都可以输入命令p 变量名来查看变量：

(Pdb) p s
'0'
(Pdb) p n
0

输入命令q结束调试，退出程序

(Pdb) n
ZeroDivisionError: 'integer division or modulo by zero'
> /Users/michael/Github/sicp/err.py(4)<module>()
-> print 10 / n
(Pdb) q

# err.py
import pdb

s = '0'
n = int(s)
pdb.set_trace() # 运行到这里会自动暂停
print 10 / n

运行代码，程序会自动在pdb.set_trace()暂停并进入pdb调试环境，可以用命令p查看变量，或者用命令c继续运行：

$ python err.py 
> /Users/michael/Github/sicp/err.py(7)<module>()
-> print 10 / n
(Pdb) p n
0
(Pdb) c
Traceback (most recent call last):
  File "err.py", line 7, in <module>
    print 10 / n
ZeroDivisionError: integer division or modulo by zero
☰