inspect模块---检查活动对象

inspect模块提供了一些有用的函数来帮助获取有关活动对象（如模块，类，方法，函数，跟踪，框架对象和代码对象）的信息。例如，它可以帮助您检查类的内容，检索方法的源代码，提取和格式化函数的参数列表，或获取显示详细追溯所需的所有信息。

这个模块提供了四种主要的服务：

类型检查，

获取源代码，

检查类和函数，

以及检查解释器堆栈

一、type and members

1. inspect.getmembers(object[, predicate])

第二个参数通常可以根据需要调用如下16个方法；

返回值为object的所有成员，以（name,value）对组成的列表

inspect.ismodule(object)： 是否为模块

inspect.isclass(object)：是否为类

inspect.ismethod(object)：是否为方法（bound method written in python）

inspect.isfunction(object)：是否为函数(python function, including lambda expression)

inspect.isgeneratorfunction(object)：是否为python生成器函数

inspect.isgenerator(object):是否为生成器

inspect.istraceback(object)： 是否为traceback

inspect.isframe(object)：是否为frame

inspect.iscode(object)：是否为code

inspect.isbuiltin(object)：是否为built-in函数或built-in方法

inspect.isroutine(object)：是否为用户自定义或者built-in函数或方法

inspect.isabstract(object)：是否为抽象基类

inspect.ismethoddescriptor(object)：是否为方法标识符

inspect.isdatadescriptor(object)：是否为数字标识符，数字标识符有__get__ 和__set__属性； 通常也有__name__和__doc__属性

inspect.isgetsetdescriptor(object)：是否为getset descriptor

inspect.ismemberdescriptor(object)：是否为member descriptor

inspect的getmembers()方法可以获取对象（module、class、method等）的如下属性：

Type	Attribute	Description	Notes
module	__doc__	documentation string
	__file__	filename (missing for built-in modules)
class	__doc__	documentation string
	__module__	name of module in which this class was defined
method	__doc__	documentation string
	__name__	name with which this method was defined
	im_class	class object that asked for this method	(1)
	im_func or __func__	function object containing implementation of method
	im_self or __self__	instance to which this method is bound, or None
function	__doc__	documentation string
	__name__	name with which this function was defined
	func_code	code object containing compiled function bytecode
	func_defaults	tuple of any default values for arguments
	func_doc	(same as __doc__)
	func_globals	global namespace in which this function was defined
	func_name	(same as __name__)
generator	__iter__	defined to support iteration over container
	close	raises new GeneratorExit exception inside the generator to terminate the iteration
	gi_code	code object
	gi_frame	frame object or possibly None once the generator has been exhausted
	gi_running	set to 1 when generator is executing, 0 otherwise
	next	return the next item from the container
	send	resumes the generator and “sends” a value that becomes the result of the current yield-expression
	throw	used to raise an exception inside the generator
traceback	tb_frame	frame object at this level
	tb_lasti	index of last attempted instruction in bytecode
	tb_lineno	current line number in Python source code
	tb_next	next inner traceback object (called by this level)
frame	f_back	next outer frame object (this frame’s caller)
	f_builtins	builtins namespace seen by this frame
	f_code	code object being executed in this frame
	f_exc_traceback	traceback if raised in this frame, or None
	f_exc_type	exception type if raised in this frame, or None
	f_exc_value	exception value if raised in this frame, or None
	f_globals	global namespace seen by this frame
	f_lasti	index of last attempted instruction in bytecode
	f_lineno	current line number in Python source code
	f_locals	local namespace seen by this frame
	f_restricted	0 or 1 if frame is in restricted execution mode
	f_trace	tracing function for this frame, or None
code	co_argcount	number of arguments (not including * or ** args)
	co_code	string of raw compiled bytecode
	co_consts	tuple of constants used in the bytecode
	co_filename	name of file in which this code object was created
	co_firstlineno	number of first line in Python source code
	co_flags	bitmap: 1=optimized | 2=newlocals | 4=*arg |8=**arg
	co_lnotab	encoded mapping of line numbers to bytecode indices
	co_name	name with which this code object was defined
	co_names	tuple of names of local variables
	co_nlocals	number of local variables
	co_stacksize	virtual machine stack space required
	co_varnames	tuple of names of arguments and local variables
builtin	__doc__	documentation string
	__name__	original name of this function or method
	__self__	instance to which a method is bound, or None

2. inspect.getmoduleinfo(path)： 返回一个命名元组<named tuple>(name,
suffix, mode, module_type)

　　name：模块名（不包括其所在的package）

suffix：

mode：open()方法的模式，如：'r', 'a'等

module_type: 整数，代表了模块的类型

3. inspect.getmodulename(path)：根据path返回模块名（不包括其所在的package）

二、Retrieving source code

1. inspect.getdoc(object)： 获取object的documentation信息

2. inspect.getcomments(object)

3. inspect.getfile(object): 返回对象的文件名

4. inspect.getmodule(object)：返回object所属的模块名

5. inspect.getsourcefile(object)： 返回object的python源文件名；object不能使built-in的module, class, mothod

6. inspect.getsourcelines(object)：返回object的python源文件代码的内容，行号+代码行

7. inspect.getsource(object)：以string形式返回object的源代码

8. inspect.cleandoc(doc)：

三、class and functions

1. inspect.getclasstree(classes[, unique])

2. inspect.getargspec(func)

3. inspect.getargvalues(frame)

4. inspect.formatargspec(args[, varargs, varkw, defaults, formatarg, formatvarargs, formatvarkw, formatvalue, join])

5. inspect.formatargvalues(args[, varargs, varkw, locals, formatarg, formatvarargs, formatvarkw, formatvalue, join])

6. inspect.getmro(cls)： 元组形式返回cls类的基类（包括cls类），以method resolution顺序;通常cls类为元素的第一个元素

7. inspect.getcallargs(func[, *args][, **kwds])：将args和kwds参数到绑定到为func的参数名；对bound方法，也绑定第一个参数（通常为self）到相应的实例；返回字典，对应参数名及其值；

>>> from inspect import getcallargs
>>> def f(a, b=1, *pos, **named):
...     pass
>>> getcallargs(f, 1, 2, 3)
{'a': 1, 'named': {}, 'b': 2, 'pos': (3,)}
>>> getcallargs(f, a=2, x=4)
{'a': 2, 'named': {'x': 4}, 'b': 1, 'pos': ()}
>>> getcallargs(f)
Traceback (most recent call last):
...
TypeError: f() takes at least 1 argument (0 given)

四、The interpreter stack

1. inspect.getframeinfo(frame[, context])

2. inspect.getouterframes(frame[, context])

3. inspect.getinnerframes(traceback[, context])

4. inspect.currentframe()

5. inspect.stack([context])

6. inspect.trace([context])

今天看RYU源码时，发现一个inspect模块，RYU使用了该模块的getmembers函数来获取ryu app的app类。

函数原型是 inspect.getmembers(object[, predicate])

功能： 从一个Object中获取符合predicate的元素的list，元素的形式是（name，value）
predicate可以是ismodule(), isclass(), ismethod(), isfunction(), isgeneratorfunction(),
isgenerator(), istraceback(), isframe(), iscode(), isbuiltin(),isroutine()，这些验证函数。

看一个例子

import inspect
class C():
     class CC():
        def foo3():
        print "foo3"
     def foo():
        print "foo"
    def foo2():
        print "foo2"
cls = inspect.getmembers(C,inspect.ismethod)
print cls

执行的结果是