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
