Python调试器:单步执行您以交互方式调用的函数

Question

Python非常酷,但不幸的是,它的调试器不如perl -d好.

在试验代码时,我常常做的一件事是从调试器中调用一个函数,然后进入该函数,如下所示:

# NOTE THAT THIS PROGRAM EXITS IMMEDIATELY WITHOUT CALLING FOO()
~> cat -n /tmp/show_perl.pl
1  #!/usr/local/bin/perl
2
3  sub foo {
4      print "hi\n";
5      print "bye\n";
6  }
7
8  exit 0;

~> perl -d /tmp/show_perl.pl

Loading DB routines from perl5db.pl version 1.28
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(/tmp/show_perl.pl:8):    exit 0;

# MAGIC HAPPENS HERE -- I AM STEPPING INTO A FUNCTION THAT I AM CALLING INTERACTIVELY
  DB<1> s foo() 
main::((eval 6)[/usr/local/lib/perl5/5.8.6/perl5db.pl:628]:3):
3:      foo();


  DB<<2>> s
main::foo(/tmp/show_perl.pl:4):     print "hi\n";


  DB<<2>> n
hi
main::foo(/tmp/show_perl.pl:5):     print "bye\n";


  DB<<2>> n
bye


  DB<2> n
Debugged program terminated.  Use q to quit or R to restart,
  use O inhibit_exit to avoid stopping after program termination,
  h q, h R or h O to get additional info.  

  DB<2> q

当尝试逐步执行函数处理各种不同输入以找出失败原因时,这非常有用.但是,它似乎无法在pdb或pydb中工作(我将向上面显示一个等效的python示例,但它会导致一个大的异常堆栈转储).

所以我的问题是双重的:

1. 我错过了什么吗？
2. 是否有一个python调试器确实让我这样做？

显然我可以自己将调用放在代码中,但我喜欢以交互方式工作,例如.当我想尝试使用稍微不同的参数集调用时,不必从头开始.

Answer 1

我已经回答了我自己的问题!这是pydb中的"debug"命令:

~> cat -n /tmp/test_python.py
     1  #!/usr/local/bin/python
     2
     3  def foo():
     4      print "hi"
     5      print "bye"
     6
     7  exit(0)
     8

~> pydb /tmp/test_python.py
(/tmp/test_python.py:7):  <module>
7 exit(0)


(Pydb) debug foo()
ENTERING RECURSIVE DEBUGGER
------------------------Call level 11
(/tmp/test_python.py:3):  foo
3 def foo():

((Pydb)) s
(/tmp/test_python.py:4):  foo
4     print "hi"

((Pydb)) s
hi
(/tmp/test_python.py:5):  foo
5     print "bye"


((Pydb)) s
bye
------------------------Return from level 11 (<type 'NoneType'>)
----------------------Return from level 10 (<type 'NoneType'>)
LEAVING RECURSIVE DEBUGGER
(/tmp/test_python.py:7):  <module>

Answer 2

您也可以使用pdb以交互方式调试函数,前提是您要调试的脚本最后不会退出():

$ cat test.py
#!/usr/bin/python

def foo(f, g):
        h = f+g
        print h
        return 2*f

要调试,启动交互式python会话并导入pdb:

$ python
Python 2.5.1 (r251:54869, Apr 18 2007, 22:08:04) 
[GCC 4.0.1 (Apple Computer, Inc. build 5367)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pdb
>>> import test
>>> pdb.runcall(test.foo, 1, 2)
> /Users/simon/Desktop/test.py(4)foo()
-> h = f+g
(Pdb) n
> /Users/simon/Desktop/test.py(5)foo()
-> print h
(Pdb) 

pdb模块附带python,并在http://docs.python.org/modindex.html的模块文档中进行了说明