Python的反射机制可以动态获取对象信息以及动态调用对象，本文介绍如何获取对象中的函数注释信息以及参数信息。

定义一个Person类：

class Person():    def talk(self, name, age, height=None):        """talk function        :return:        """        print(f"My name is {name}")        print(f"My age is {age}")        if height is not None:            print(f"My height is {height}")

dir() 命令也可以获取函数的属性信息：

【资料图】

person = Person()print(dir(person))func = getattr(person, "talk")print(dir(func))

结果

["__class__", "__delattr__", "__dict__", "__dir__", "__doc__", "__eq__", "__format__", "__ge__", "__getattribute__", "__gt__", "__hash__", "__init__", "__init_subclass__", "__le__", "__lt__", "__module__", "__ne__", "__new__", "__reduce__", "__reduce_ex__", "__repr__", "__setattr__", "__sizeof__", "__str__", "__subclasshook__", "__weakref__", "talk"]["__call__", "__class__", "__delattr__", "__dir__", "__doc__", "__eq__", "__format__", "__func__", "__ge__", "__get__", "__getattribute__", "__gt__", "__hash__", "__init__", "__init_subclass__", "__le__", "__lt__", "__ne__", "__new__", "__reduce__", "__reduce_ex__", "__repr__", "__self__", "__setattr__", "__sizeof__", "__str__", "__subclasshook__"]

获取函数注释信息

可以通过 doc属性来获取注释信息（三引号括起来的注释）：

func = getattr(person, "talk")print(func.__doc__)

结果

talk function        :return:

获取函数参数

1、 通过 __code__ 属性读取函数参数信息

>> print(dir(func.__code__))["__class__", "__delattr__", "__dir__", "__doc__", "__eq__", "__format__", "__ge__", "__getattribute__", "__gt__", "__hash__", "__init__", "__init_subclass__", "__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_kwonlyargcount", "co_lnotab", "co_name", "co_names", "co_nlocals", "co_stacksize", "co_varnames"]>>#学习中遇到问题没人解答？小编创建了一个Python学习交流群：725638078print("co_name: ", func.__code__.co_name)  # 返回函数名print("co_argcount: ", func.__code__.co_argcount)  # 返回函数的参数个数print("co_varnames: ",func.__code__.co_varnames) # 返回函数的参数print("co_filename: ", func.__code__.co_filename) # 返回文件绝对路径print("co_consts: ", func.__code__.co_consts)print("co_firstlineno: ",func.__code__.co_firstlineno) # 返回函数行号print("co_kwonlyargcount: ",func.__code__.co_kwonlyargcount) # 关键字参数print("co_nlocals: ",func.__code__.co_nlocals) # 返回局部变量个数

结果

co_name:  talkco_argcount:  4co_varnames:  ("self", "name", "age", "height")co_filename:  D:/ProgramWorkspace/PythonNotes/00-Python-Essentials/demo.pyco_consts:  ("talk function\n        :return:\n        ", "My name is ", "My age is ", None, "My height is ")co_firstlineno:  44co_kwonlyargcount:  0co_nlocals:  4

通过 code.co_varnames 可以获取参数名，参数默认值可以通过如下方式获得：

print(func.__defaults__)

结果

(None,)

2、通过inspect库来读取函数参数信息

除了用__code__ 属性外还可以使用inspect库来读取函数参数，使用getfullargspec和signature方法来读取函数参数：

import inspect# inspect.getargspec(func) # python2argspec = inspect.getfullargspec(func)print(argspec.args)print(argspec.defaults)print(argspec.varkw)sig = inspect.signature(func)print(sig)

结果

["self", "name", "age", "height"](None,)None(name, age, height=None)

也可以在函数内部使用：

class Person():    def talk(self, name, age, height=None):        """talk function        :return:        """        frame = inspect.currentframe()        args, _, _, values = inspect.getargvalues(frame)        print(inspect.getframeinfo(frame))        print(f"function name: {inspect.getframeinfo(frame).function}")        for i in args:            print(f"{i} = {values[i]}")if __name__ == "__main__":    p = Person()    p.talk("zhangsan", 18, height=175)        

结果

Traceback(filename="D:/ProgramWorkspace/PythonNotes/00-Python-Essentials/demo.py", lineno=44, function="talk", code_context=["        print(inspect.getframeinfo(frame))\n"], index=0)function name: talkself = <__main__.Person object at 0x0000023E4CF17B08>name = zhangsanage = 18height = 175