python--inspect

inspect是专门用来收集python对象的信息的,可以获取参数信息,原码,解析堆栈,判断对象类型等等。下面看看一些主要用法

 

import inspect


# 1.判断是不是一个模块
import tornado
print(inspect.ismodule(tornado))  # True


# 2.判断是不是一个类
Foo = type("Foo", (object, ), {})
print(inspect.isclass(Foo))  # True


# 3.判断是不是一个方法。说白了就是判断是不是类里面定义的一个函数,
class A:

    def m(self):
        ...


print(inspect.ismethod(A().m), type(A().m))  # True <class 'method'>


# 4.判断是不是一个方法描述符。说白了就是首先得是一个类的实例对象,并且这个类里面定义了__get__方法,且没有定义__set__方法
class A:

    def __get__(self, instance, owner):
        ...


print(inspect.ismethoddescriptor(A()))


# 5.判断是不是一个数据描述符。说白了就是首先得是一个类的实例对象,并且这个类里面定义了__get__方法和__set__方法
class A:

    def __get__(self, instance, owner):...

    def __set__(self, instance, value):...


print(inspect.isdatadescriptor(A()))  # True


# 6.判断是不是一个函数
print(inspect.isfunction(lambda: ...))  # True


# 7.判断是不是一个生成器函数
def foo(): yield 1


print(inspect.isgeneratorfunction(foo))  # True
# 同时生成器函数也是一个函数
print(inspect.isfunction(foo))  # True


# 8.判断是不是一个协程函数,协程函数必须是由async def语法定义的函数,使用types.coroutine或者asyncio.coroutine装饰的函数都不是
async def foo():
    ...


print(inspect.iscoroutinefunction(foo))  # True


# 9.判断是不是一个异步生成器函数,异步生成器函数是由async def语法定义,并且函数体内部要包含yield的函数
async def foo():
    yield 1


print(inspect.isasyncgenfunction(foo))  # True


# 10.判断是不是一个异步生成器,就是异步生成器函数加上小括号
print(inspect.isasyncgen(foo()))  # True


# 11.判断是不是一个生成器, 就是生成器函数加上小括号
def gen(): yield 1


print(inspect.isgenerator(gen()))  # True


# 12.判断是不是一个协程,就是协程函数加上小括号
async def foo(): ...


print(inspect.iscoroutine(foo()))  # True


# 13.判断是不是一个可以awaitable,说白了就是await一个迭代器对象
async def foo():
    await [1, 2, 3].__iter__()


print(inspect.isawaitable(foo()))  # True


# 14.判断是不是一个栈帧
def foo():
    # 该函数可以获取栈帧
    frame = inspect.currentframe()
    return frame


print(inspect.isframe(foo()))  # True


# 15.判断是是不是code
def foo(): ...


print(inspect.iscode(foo.__code__))  # True


# 16.获取成员
class A:
    def __init__(self):...

    def parse(self): ...


import pprint
pprint.pprint(inspect.getmembers(A))
'''
[('__class__', <class 'type'>),
 ('__delattr__', <slot wrapper '__delattr__' of 'object' objects>),
 ('__dict__',
  mappingproxy({'__dict__': <attribute '__dict__' of 'A' objects>,
                '__doc__': None,
                '__init__': <function A.__init__ at 0x000001FEF344CEA0>,
                '__module__': '__main__',
                '__weakref__': <attribute '__weakref__' of 'A' objects>,
                'parse': <function A.parse at 0x000001FEF344CF28>})),
 ('__dir__', <method '__dir__' of 'object' objects>),
 ('__doc__', None),
 ('__eq__', <slot wrapper '__eq__' of 'object' objects>),
 ('__format__', <method '__format__' of 'object' objects>),
 ('__ge__', <slot wrapper '__ge__' of 'object' objects>),
 ('__getattribute__', <slot wrapper '__getattribute__' of 'object' objects>),
 ('__gt__', <slot wrapper '__gt__' of 'object' objects>),
 ('__hash__', <slot wrapper '__hash__' of 'object' objects>),
 ('__init__', <function A.__init__ at 0x000001FEF344CEA0>),
 ('__init_subclass__',
  <built-in method __init_subclass__ of type object at 0x000001FEF2E6F628>),
 ('__le__', <slot wrapper '__le__' of 'object' objects>),
 ('__lt__', <slot wrapper '__lt__' of 'object' objects>),
 ('__module__', '__main__'),
 ('__ne__', <slot wrapper '__ne__' of 'object' objects>),
 ('__new__', <built-in method __new__ of type object at 0x00007FFFC0D98EC0>),
 ('__reduce__', <method '__reduce__' of 'object' objects>),
 ('__reduce_ex__', <method '__reduce_ex__' of 'object' objects>),
 ('__repr__', <slot wrapper '__repr__' of 'object' objects>),
 ('__setattr__', <slot wrapper '__setattr__' of 'object' objects>),
 ('__sizeof__', <method '__sizeof__' of 'object' objects>),
 ('__str__', <slot wrapper '__str__' of 'object' objects>),
 ('__subclasshook__',
  <built-in method __subclasshook__ of type object at 0x000001FEF2E6F628>),
 ('__weakref__', <attribute '__weakref__' of 'A' objects>),
 ('parse', <function A.parse at 0x000001FEF344CF28>)]
'''


# 17.获取mro,包括自己
class A(object): ...


print(inspect.getmro(A))  # (<class '__main__.A'>, <class 'object'>)


# 18.获取doc
print(inspect.getdoc(int))
'''
int([x]) -> integer
int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments
are given.  If x is a number, return x.__int__().  For floating point
numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string,
bytes, or bytearray instance representing an integer literal in the
given base.  The literal can be preceded by '+' or '-' and be surrounded
by whitespace.  The base defaults to 10.  Valid bases are 0 and 2-36.
Base 0 means to interpret the base from the string as an integer literal.
>>> int('0b100', base=0)
4
'''


# 19.查看对象被定义在哪一个文件里面
from pandas import DataFrame
print(inspect.getfile(DataFrame))  # C:\python37\lib\site-packages\pandas\core\frame.py
# 当然也可以是一个模块
import requests
print(inspect.getfile(requests))  # C:\python37\lib\site-packages\requests\__init__.py


# 20.返回一个给定对象的模块名,不过存在不存在,感觉没卵用
print(inspect.getmodulename(r"C:\python37\lib\site-packages\peeaaawee.py"))  # peeaaawee


# 21.和getfile类似
print(inspect.getabsfile(DataFrame))  # c:\python37\lib\site-packages\pandas\core\frame.py


# 22.获取参数信息,但需要传入字节码
def foo(a, b=1): ...


print(inspect.getargs(foo.__code__))  # Arguments(args=['a', 'b'], varargs=None, varkw=None)
print(inspect.getargs(foo.__code__).args)  # ['a', 'b']


# 23.获取参数信息吗, 传入函数即可
def foo(a, b=1): ...


print(inspect.getfullargspec(foo))  # FullArgSpec(args=['a', 'b'], varargs=None, varkw=None, defaults=(1,), kwonlyargs=[], kwonlydefaults=None, annotations={})
print(foo.__defaults__)  # (1,)

  

import inspect


def bar():
    name = "Mashiro"
    age = 16
    return foo()


def foo():
    name = "Satori"
    age = 18
    return inspect.currentframe()


# frame叫做栈帧,表示当前函数调用栈的某一帧,是一个上下文。正所谓在python中一切皆对象,这个栈帧也是一个对象。
# 函数执行要在相应的栈帧中执行
# 栈帧有一下几大特性,
# f_back:调用者的上一级栈帧
# f_code:字节码
# f_lineno:栈帧所在的哪一行

# frame是定义在foo函数里面,所以currentframe拿到的是foo的栈帧
# 但是又是通过bar来调用的,所以foo的上一级栈帧就是bar的栈帧
f = bar()
print(f.f_back)  # <frame at 0x000001E1FF4CF458, file 'D:/乱七八糟的/龙卷风/3.py', line 5, code bar>
print(f.f_code)  # <code object foo at 0x000001E1FFEE3F60, file "D:/乱七八糟的/龙卷风/3.py", line 8>
print(f.f_lineno)  # 13

# 这个f_code里面也有很多的属性
# co_name:获取栈帧所对应的函数名
print(f.f_code.co_name)  # foo
# co_filename:获取相应的文件名
print(f.f_code.co_filename)  # D:/乱七八糟的/龙卷风/3.py

print(f.f_back.f_code.co_name)  # bar
print(f.f_back.f_code.co_filename)  # D:/乱七八糟的/龙卷风/3.py


# 查看当前的局部变量,可以看到由于栈帧还在,所以局部变量依旧存储在堆上
print(f.f_locals)  # {'name': 'Satori', 'age': 18}
# 同理它的上一级栈帧也是
print(f.f_back.f_locals)  # {'name': 'Mashiro', 'age': 16}


# 如果是生成器的话,就不需要了
def gen():
    yield 1
    name = ("xxx", )
    yield 2
    age = 16
    yield 3
    gender = "f"
    yield 4
    return


g = gen()
# 生成器有一个gi_frame属性,可以直接获取
print(g.gi_frame.f_locals)  # {}
print(next(g))  # 1
print(g.gi_frame.f_locals)  # {}
print(next(g))  # 2
print(g.gi_frame.f_locals)  # {'name': 'xxx'}
print(next(g))  # 3
print(g.gi_frame.f_locals)  # {'name': 'xxx', 'age': 16}
print(next(g))  # 4
print(g.gi_frame.f_locals)  # {'name': 'xxx', 'age': 16, 'gender': 'f'}
try:
    next(g)
except StopIteration as e:
    print(e.value)  # result

  

  

 

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转载自www.cnblogs.com/traditional/p/10269365.html
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