Python函数信息

浏览数：26 / 时间：2015年06月08日

Python函数func的信息可以通过func.func_*和func.func_code来获取

一、先看看它们的应用吧：

1.获取原函数名称：

1 >>> def yes():pass
2 
3 >>> a=yes
4 >>> a.func_name
5 ‘yes‘
6 >>>

2.获取函数的flags【后面有用，先说这个】

[python docs]:The following flag bits are defined for co_flags: bit 0x04 is set if the function uses the *arguments syntax to accept an arbitrary number of positional arguments; bit 0x08 is set if the function uses the **keywords syntax to accept arbitrary keyword arguments; bit 0x20 is set if the function is a generator.

由这段Python官方文档可知，函数的flags与参数的定义方式有关，看看下面的试验：

>>> def yes():pass

>>> yes.func_code.co_flags
67
>>> def yes(a):pass

>>> yes.func_code.co_flags
67
>>> def yes(a,b=3):pass

>>> yes.func_code.co_flags
67
>>> def yes(*args):pass

>>> yes.func_code.co_flags
71
>>> def yes(a,*args):pass

>>> yes.func_code.co_flags
71
>>> def yes(a,b=32,*args):pass

>>> yes.func_code.co_flags
71
>>> def yes(*args,**kw):pass

>>> yes.func_code.co_flags
79
>>> def yes(a,*args,**kw):pass

>>> yes.func_code.co_flags
79
>>> def yes(a,b=3,*args,**kw):pass

>>> yes.func_code.co_flags
79
>>> def yes(**kw):pass

>>> yes.func_code.co_flags
75
>>> def yes(a,**kw):pass

>>> yes.func_code.co_flags
75
>>> def yes(a,b=1,**kw):pass

>>> yes.func_code.co_flags
75
>>>
>>> yes=(x for x in range(100))
>>> yes
<generator object <genexpr> at 0x0000000002FF22D0>
>>> [x for x in dir(yes) if not x.startswith(‘_‘)]
[‘close‘, ‘gi_code‘, ‘gi_frame‘, ‘gi_running‘, ‘next‘, ‘send‘, ‘throw‘]
>>> dir(yes)
[‘__class__‘, ‘__delattr__‘, ‘__doc__‘, ‘__format__‘, ‘__getattribute__‘, ‘__hash__‘, ‘__init__‘, ‘__iter__‘, ‘__name__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘close‘, ‘gi_code‘, ‘gi_frame‘, ‘gi_running‘, ‘next‘, ‘send‘, ‘throw‘]
>>> dir(yes.gi_code)
[‘__class__‘, ‘__cmp__‘, ‘__delattr__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__le__‘, ‘__lt__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘co_argcount‘, ‘co_cellvars‘, ‘co_code‘, ‘co_consts‘, ‘co_filename‘, ‘co_firstlineno‘, ‘co_flags‘, ‘co_freevars‘, ‘co_lnotab‘, ‘co_name‘, ‘co_names‘, ‘co_nlocals‘, ‘co_stacksize‘, ‘co_varnames‘]
>>> [x for x in dir(yes.gi_code) if x.startswith(‘co_‘)]
[‘co_argcount‘, ‘co_cellvars‘, ‘co_code‘, ‘co_consts‘, ‘co_filename‘, ‘co_firstlineno‘, ‘co_flags‘, ‘co_freevars‘, ‘co_lnotab‘, ‘co_name‘, ‘co_names‘, ‘co_nlocals‘, ‘co_stacksize‘, ‘co_varnames‘]
>>> yes.gi_code.co_flags
99
>>> yes.next()
0
>>> yes.next()
1
>>> yes.gi_code.co_varnames
(‘.0‘, ‘x‘)
>>> for name in [x for x in dir(yes.gi_code) if x.startswith(‘co_‘)]:
    print ‘yes.gi_code.%s = %r‘%(name,eval(‘yes.gi_code.%s‘%name))

    
yes.gi_code.co_argcount = 1
yes.gi_code.co_cellvars = ()
yes.gi_code.co_code = ‘|\x00\x00]\x0b\x00}\x01\x00|\x01\x00V\x01q\x03\x00d\x00\x00S‘
yes.gi_code.co_consts = (None,)
yes.gi_code.co_filename = ‘<pyshell#46>‘
yes.gi_code.co_firstlineno = 1
yes.gi_code.co_flags = 99
yes.gi_code.co_freevars = ()
yes.gi_code.co_lnotab = ‘\x06\x00‘
yes.gi_code.co_name = ‘<genexpr>‘
yes.gi_code.co_names = ()
yes.gi_code.co_nlocals = 2
yes.gi_code.co_stacksize = 2
yes.gi_code.co_varnames = (‘.0‘, ‘x‘)
>>>

【1】function没有*args或**kw时，func.func_code.co_flags=67;

【2】function有*args没有**kw时，func.func_code.co_flags=71;

【3】function没有*args有**kw时，func.func_code.co_flags=75;

【4】function既有*args也有**kw时，func.func_code.co_flags=79;

【5】function是一个generator时，func.gi_code.co_flags=99.

3.获取func函数的所有位置参数的个数：

func.func_code.co_argcount

4.获取func函数签名：

[1]callable(func)，True=>function，False=>generator

[2]func的定义的所有位置参数变量名：pVars=func.func_code.co_varnames[:func.func_code.co_argcount]

[3]func的默认参数及默认值：func.func_defaults

[4]func的所有带默认值的参数的参数名：dVars=pVars[-len(func.func_defaults):]【当然首先要判断func.func_defaults=?=None】

[5]根据func.func_code.co_flags来判断有无带星号的参数，按照上面的判定规则：

a.如果func.func_code.co_flags==67，无带星号的参数；

b.如果func.func_code.co_flags==71，只有带一个星号的参数，它的参数名是func.func_code.co_varnames[func.func_code.co_argcount]

c.如果func.func_code.co_flags==75，只有带两个星号的参数，它的参数名是func.func_code.co_varnames[func.func_code.co_argcount]

d. 如果func.func_code.co_flags==79，有两个带星号的参数，它们的参数名是 func.func_code.co_varnames[func.func_code.co_argcount:func.func_code.co_argcount+2]，其中第一个是带一个星号的，第二个是带两个星号的

因为：

1 >>> def yes(**kw,*args):pass
2 SyntaxError: invalid syntax
3 >>>

故如此。到此，func函数的函数签名就可以被还原了。

二、func.func_*

1.func.func_closure：
2.func.func_code：详见下面第三条
3.func.func_defaults：tuple=>func函数的参数中的所有默认值
4.func.func_dict
5.func.func_doc：str=>func函数的文档字符串
6.func.func_globals：dict=>func函数的全局环境
7.func.func_name：str=>func函数的函数名

三、func.func_code【翻译有不周之处请指正】

1.func.func_code.co_argcount：co_argcount is the number of positional arguments (including arguments with default values);

int=>func函数的位置参数的个数，实际上python函数定义时定义的前面不加星号的所有参数都是位置参数，我们所说的关键字参数只是调用时候的说法。
2.func.func_code.co_cellvars：co_cellvars is a tuple containing the names of local variables that are referenced by nested functions;

tuple=>func函数中所有被其嵌套函数引用了的func函数的局部变量
3.func.func_code.co_code：co_code is a string representing the sequence of bytecode instructions;

str=>func函数的编译后的字节码
4.func.func_code.co_consts：co_consts is a tuple containing the literals used by the bytecode;

tuple=>func函数中的所有常量，如0,True,‘‘,None
5.func.func_code.co_filename：co_filename is the filename from which the code was compiled;

str=>func函数的定义所在的源文件路径
6.func.func_code.co_firstlineno：co_firstlineno is the first line number of the function;

int=>func函数的定义在其源文件中的第一行的行号
7.func.func_code.co_flags：co_flags is an integer encoding a number of flags for the interpreter;

int=>func函数参数传递方式的编码，比如*args,**kw等形式
8.func.func_code.co_freevars：co_freevars is a tuple containing the names of free variables;

tuple=>func函数中所有的自由变量的名称
9.func.func_code.co_lnotab：co_lnotab is a string encoding the mapping from bytecode offsets to line numbers (for details see the source code of the interpreter);
10.func.func_code.co_name：co_name gives the function name;

str=>func函数的名称
11.func.func_code.co_names：co_names is a tuple containing the names used by the bytecode;

tuple=>func函数中所有的被字节码使用到的名称，比如模块名，方法名等
12.func.func_code.co_nlocals：co_nlocals is the number of local variables used by the function (including arguments);

int=>func函数用到的局部变量的数目（包括参数）
13.func.func_code.co_stacksize：co_stacksize is the required stack size (including local variables);

func函数所需的堆栈大小（包括所有局部变量）
14.func.func_code.co_varnames：co_varnames is a tuple containing the names of the local variables (starting with the argument names);

tuple=>func函数中所有使用到的local variables的名称，参数按顺序排在最前面，其它的按在代码中出现的顺序排列；

四、看下面的一个实验：

 1 #coding=utf-8
 2 import os,sys
 3 
 4 def decorator(printResult=False):
 5     def _decorator(func):
 6         name=func.func_name
 7         print ‘%s() was post to _decorator()‘%name
 8         def __decorator(*args,**kw):
 9             print ‘Call the function %s() in __decorator().‘%10                   func.func_name
11             if printResult:
12                 print func(*args,**kw),‘#print in __decorator().‘
13             else:
14                 return func(*args,**kw)
15         return __decorator
16     return _decorator
17 
18 def GetRandName(length,isVar=False):
19     u‘‘‘Get random name with string.letters+‘_‘+string.digits
20 
21     length=>The length of name.
22     isVar=>The name must be a varname.
23     ‘‘‘
24     varName,chars=[],string.letters+‘_‘+string.digits
25     if isVar:
26         varName.append(chars[:53][random.randint(0,52)])
27         length-=1
28     for i in range(length):
29         varName.append(chars[random.randint(0,62)])
30     varName=‘‘.join(varName)
31     return varName
32 
33 def func_info(func):
34     print ‘%s() information:‘%func.func_name
35     for name in [x for x in dir(func) if x.startswith(‘func_‘)]:
36         print ‘%s.%s = %r‘%(func.func_name,name,
37             eval(‘%s.%s‘%(func.func_name,name)))
38     for name in [x for x in dir(func.func_code) if x.startswith(‘co_‘)]:
39         print ‘%s.func_code.%s = %r‘%(func.func_name,name,
40             eval(‘%s.func_code.%s‘%(func.func_name,name)))
41 #输出GetRandName()函数的信息
42 func_info(GetRandName)
43 print ‘-‘*80
44 #输出decorator()函数的信息
45 func_info(decorator)
46 print ‘-‘*80
47 #将GetRandName函数用装饰器先装饰一下
48 GetRandName=decorator(True)(GetRandName)
49 #装饰后GetRandName变成__decorator()函数
50 print ‘GetRandName=%r‘%GetRandName
51 #输出此时的GetRandName即__decorator()函数的信息
52 print ‘%s() information:‘%GetRandName.func_name
53 for name in [x for x in dir(GetRandName) if x.startswith(‘func_‘)]:
54     print ‘%s.%s = %r‘%(GetRandName.func_name,name,
55         eval(‘GetRandName.%s‘%name))
56 for name in [x for x in dir(GetRandName.func_code) if x.startswith(‘co_‘)]:
57     print ‘%s.func_code.%s = %r‘%(GetRandName.func_name,name,
58         eval(‘GetRandName.func_code.%s‘%name))

运行结果：

 1 Python 2.7.8 (default, Jun 30 2014, 16:08:48) [MSC v.1500 64 bit (AMD64)] on win32
 2 Type "copyright", "credits" or "license()" for more information.
 3 >>> ================================ RESTART ================================
 4 >>> 
 5 GetRandName() information:
 6 GetRandName.func_closure = None
 7 GetRandName.func_code = <code object GetRandName at 0000000002107F30, file "E:\文档\程序库\Python程序\func_information.py", line 18>
 8 GetRandName.func_defaults = (False,)
 9 GetRandName.func_dict = {}
10 GetRandName.func_doc = u"Get random name with string.letters+‘_‘+string.digits\n\n    length=>The length of name.\n    isVar=>The name must be a varname.\n    "
11 GetRandName.func_globals = {‘__builtins__‘: <module ‘__builtin__‘ (built-in)>, ‘__file__‘: ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘, ‘func_info‘: <function func_info at 0x0000000002BDD3C8>, ‘__package__‘: None, ‘sys‘: <module ‘sys‘ (built-in)>, ‘__name__‘: ‘__main__‘, ‘GetRandName‘: <function GetRandName at 0x0000000002BE0D68>, ‘os‘: <module ‘os‘ from ‘D:\Python27\lib\os.pyc‘>, ‘__doc__‘: None, ‘decorator‘: <function decorator at 0x00000000021199E8>}
12 GetRandName.func_name = ‘GetRandName‘
13 GetRandName.func_code.co_argcount = 2
14 GetRandName.func_code.co_cellvars = ()
15 GetRandName.func_code.co_code = ‘g\x00\x00t\x00\x00j\x01\x00d\x01\x00\x17t\x00\x00j\x02\x00\x17\x02}\x02\x00}\x03\x00|\x01\x00rO\x00|\x02\x00j\x03\x00|\x03\x00d\x02\x00 t\x04\x00j\x05\x00d\x03\x00d\x04\x00\x83\x02\x00\x19\x83\x01\x00\x01|\x00\x00d\x05\x008}\x00\x00n\x00\x00x1\x00t\x06\x00|\x00\x00\x83\x01\x00D]#\x00}\x04\x00|\x02\x00j\x03\x00|\x03\x00t\x04\x00j\x05\x00d\x03\x00d\x06\x00\x83\x02\x00\x19\x83\x01\x00\x01q\\\x00Wd\x07\x00j\x07\x00|\x02\x00\x83\x01\x00}\x02\x00|\x02\x00S‘
16 GetRandName.func_code.co_consts = (u"Get random name with string.letters+‘_‘+string.digits\n\n    length=>The length of name.\n    isVar=>The name must be a varname.\n    ", ‘_‘, 53, 0, 52, 1, 62, ‘‘)
17 GetRandName.func_code.co_filename = ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘
18 GetRandName.func_code.co_firstlineno = 18
19 GetRandName.func_code.co_flags = 67
20 GetRandName.func_code.co_freevars = ()
21 GetRandName.func_code.co_lnotab = ‘\x00\x06\x1b\x01\x06\x01!\x01\r\x01\x13\x01!\x01\x0f\x01‘
22 GetRandName.func_code.co_name = ‘GetRandName‘
23 GetRandName.func_code.co_names = (‘string‘, ‘letters‘, ‘digits‘, ‘append‘, ‘random‘, ‘randint‘, ‘range‘, ‘join‘)
24 GetRandName.func_code.co_nlocals = 5
25 GetRandName.func_code.co_stacksize = 6
26 GetRandName.func_code.co_varnames = (‘length‘, ‘isVar‘, ‘varName‘, ‘chars‘, ‘i‘)
27 --------------------------------------------------------------------------------
28 decorator() information:
29 decorator.func_closure = None
30 decorator.func_code = <code object decorator at 0000000002107AB0, file "E:\文档\程序库\Python程序\func_information.py", line 4>
31 decorator.func_defaults = (False,)
32 decorator.func_dict = {}
33 decorator.func_doc = None
34 decorator.func_globals = {‘__builtins__‘: <module ‘__builtin__‘ (built-in)>, ‘__file__‘: ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘, ‘func_info‘: <function func_info at 0x0000000002BDD3C8>, ‘__package__‘: None, ‘sys‘: <module ‘sys‘ (built-in)>, ‘__name__‘: ‘__main__‘, ‘GetRandName‘: <function GetRandName at 0x0000000002BE0D68>, ‘os‘: <module ‘os‘ from ‘D:\Python27\lib\os.pyc‘>, ‘__doc__‘: None, ‘decorator‘: <function decorator at 0x00000000021199E8>}
35 decorator.func_name = ‘decorator‘
36 decorator.func_code.co_argcount = 1
37 decorator.func_code.co_cellvars = (‘printResult‘,)
38 decorator.func_code.co_code = ‘\x87\x00\x00f\x01\x00d\x01\x00\x86\x00\x00}\x01\x00|\x01\x00S‘
39 decorator.func_code.co_consts = (None, <code object _decorator at 0000000002107830, file "E:\文档\程序库\Python程序\func_information.py", line 5>)
40 decorator.func_code.co_filename = ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘
41 decorator.func_code.co_firstlineno = 4
42 decorator.func_code.co_flags = 3
43 decorator.func_code.co_freevars = ()
44 decorator.func_code.co_lnotab = ‘\x00\x01\x0f\x0b‘
45 decorator.func_code.co_name = ‘decorator‘
46 decorator.func_code.co_names = ()
47 decorator.func_code.co_nlocals = 2
48 decorator.func_code.co_stacksize = 2
49 decorator.func_code.co_varnames = (‘printResult‘, ‘_decorator‘)
50 --------------------------------------------------------------------------------
51 GetRandName() was post to _decorator()
52 GetRandName=<function __decorator at 0x0000000002BDD4A8>
53 __decorator() information:
54 __decorator.func_closure = (<cell at 0x0000000002BF18E8: function object at 0x0000000002BE0D68>, <cell at 0x0000000002BF1828: bool object at 0x000000001E284280>)
55 __decorator.func_code = <code object __decorator at 0000000002124030, file "E:\文档\程序库\Python程序\func_information.py", line 8>
56 __decorator.func_defaults = None
57 __decorator.func_dict = {}
58 __decorator.func_doc = None
59 __decorator.func_globals = {‘name‘: ‘func_globals‘, ‘__builtins__‘: <module ‘__builtin__‘ (built-in)>, ‘__file__‘: ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘, ‘func_info‘: <function func_info at 0x0000000002BDD3C8>, ‘__package__‘: None, ‘sys‘: <module ‘sys‘ (built-in)>, ‘x‘: ‘func_name‘, ‘__name__‘: ‘__main__‘, ‘GetRandName‘: <function __decorator at 0x0000000002BDD4A8>, ‘os‘: <module ‘os‘ from ‘D:\Python27\lib\os.pyc‘>, ‘__doc__‘: None, ‘decorator‘: <function decorator at 0x00000000021199E8>}
60 __decorator.func_name = ‘__decorator‘
61 __decorator.func_code.co_argcount = 0
62 __decorator.func_code.co_cellvars = ()
63 __decorator.func_code.co_code = "d\x01\x00\x88\x00\x00j\x00\x00\x16GH\x88\x01\x00r‘\x00\x88\x00\x00|\x00\x00|\x01\x00\x8e\x00\x00Gd\x02\x00GHn\r\x00\x88\x00\x00|\x00\x00|\x01\x00\x8e\x00\x00Sd\x00\x00S"
64 __decorator.func_code.co_consts = (None, ‘Call the function %s() in __decorator().‘, ‘#print in __decorator().‘)
65 __decorator.func_code.co_filename = ‘E:\\\xce\xc4\xb5\xb5\\\xb3\xcc\xd0\xf2\xbf\xe2\\Python\xb3\xcc\xd0\xf2\\func_information.py‘
66 __decorator.func_code.co_firstlineno = 8
67 __decorator.func_code.co_flags = 31
68 __decorator.func_code.co_freevars = (‘func‘, ‘printResult‘)
69 __decorator.func_code.co_lnotab = ‘\x00\x01\x03\x01\t\x01\x06\x01\x15\x02‘
70 __decorator.func_code.co_name = ‘__decorator‘
71 __decorator.func_code.co_names = (‘func_name‘,)
72 __decorator.func_code.co_nlocals = 2
73 __decorator.func_code.co_stacksize = 3
74 __decorator.func_code.co_varnames = (‘args‘, ‘kw‘)
75 >>>