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Python內(nèi)置函數(shù)—vars的具體使用方法

 更新時(shí)間:2017年12月04日 11:02:52   作者:十月狐貍  
本篇文章主要介紹了Python內(nèi)置函數(shù)—vars的具體使用方法,小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,也給大家做個(gè)參考。一起跟隨小編過來看看吧

本文文章主要介紹了Python內(nèi)置函數(shù)—vars的具體使用方法,分享給大家,具體如下:

英文文檔:

vars([object])

Return the __dict__ attribute for a module, class, instance, or any other object with a __dict__ attribute.Objects such as modules and instances have an updateable __dict__ attribute; however, other objects may have write restrictions on their __dict__ attributes (for example, classes use a dictproxy to prevent direct dictionary updates).Without an argument, vars() acts like locals(). Note, the locals dictionary is only useful for reads since updates to the locals dictionary are ignored.

參數(shù)

object -- 對(duì)象

返回值

返回對(duì)象object的屬性和屬性值的字典對(duì)象,如果沒有參數(shù),就打印當(dāng)前調(diào)用位置的屬性和屬性值 類似 locals()。

說明

1. 當(dāng)函數(shù)不接收參數(shù)時(shí),其功能和locals函數(shù)一樣,返回當(dāng)前作用域內(nèi)的局部變量。

#不帶參數(shù)功能和locals函數(shù)一樣
>>> v1 = vars()
>>> l1 = locals()
>>> v1
{'__name__': '__main__', '__builtins__': <module 'builtins' (built-in)>, 'v1': {...}, 'l1': {...}, '__spec__': None, '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>}
>>> l1
{'__name__': '__main__', '__builtins__': <module 'builtins' (built-in)>, 'v1': {...}, 'l1': {...}, '__spec__': None, '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>}

2. 當(dāng)函數(shù)接收一個(gè)參數(shù)時(shí),參數(shù)可以是模塊、類、類實(shí)例,或者定義了__dict__屬性的對(duì)象。

#作用于模塊
>>> import time
>>> vars(time)
{'gmtime': <built-in function gmtime>, 'tzname': ('Öйú±ê׼ʱ¼ä', 'ÖйúÏÄÁîʱ'), 'timezone': -28800, 'struct_time': <class 'time.struct_time'>, 'ctime': <built-in function ctime>, 'perf_counter': <built-in function perf_counter>, 'mktime': <built-in function mktime>, 'localtime': <built-in function localtime>, 'time': <built-in function time>, '__package__': '', 'altzone': -32400, 'clock': <built-in function clock>, 'strptime': <built-in function strptime>, 'monotonic': <built-in function monotonic>, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, 'get_clock_info': <built-in function get_clock_info>, 'sleep': <built-in function sleep>, 'process_time': <built-in function process_time>, '__name__': 'time', '_STRUCT_TM_ITEMS': 9, '__spec__': ModuleSpec(name='time', loader=<class '_frozen_importlib.BuiltinImporter'>, origin='built-in'), '__doc__': 'This module provides various functions to manipulate time values.\n\nThere are two standard representations of time. One is the number\nof seconds since the Epoch, in UTC (a.k.a. GMT). It may be an integer\nor a floating point number (to represent fractions of seconds).\nThe Epoch is system-defined; on Unix, it is generally January 1st, 1970.\nThe actual value can be retrieved by calling gmtime(0).\n\nThe other representation is a tuple of 9 integers giving local time.\nThe tuple items are:\n year (including century, e.g. 1998)\n month (1-12)\n day (1-31)\n hours (0-23)\n minutes (0-59)\n seconds (0-59)\n weekday (0-6, Monday is 0)\n Julian day (day in the year, 1-366)\n DST (Daylight Savings Time) flag (-1, 0 or 1)\nIf the DST flag is 0, the time is given in the regular time zone;\nif it is 1, the time is given in the DST time zone;\nif it is -1, mktime() should guess based on the date and time.\n\nVariables:\n\ntimezone -- difference in seconds between UTC and local standard time\naltzone -- difference in seconds between UTC and local DST time\ndaylight -- whether local time should reflect DST\ntzname -- tuple of (standard time zone name, DST time zone name)\n\nFunctions:\n\ntime() -- return current time in seconds since the Epoch as a float\nclock() -- return CPU time since process start as a float\nsleep() -- delay for a number of seconds given as a float\ngmtime() -- convert seconds since Epoch to UTC tuple\nlocaltime() -- convert seconds since Epoch to local time tuple\nasctime() -- convert time tuple to string\nctime() -- convert time in seconds to string\nmktime() -- convert local time tuple to seconds since Epoch\nstrftime() -- convert time tuple to string according to format specification\nstrptime() -- parse string to time tuple according to format specification\ntzset() -- change the local timezone', 'strftime': <built-in function strftime>, 'asctime': <built-in function asctime>, 'daylight': 0}

#作用于類
>>> vars(slice)
mappingproxy({'__ne__': <slot wrapper '__ne__' of 'slice' objects>, '__getattribute__': <slot wrapper '__getattribute__' of 'slice' objects>, '__reduce__': <method '__reduce__' of 'slice' objects>, 'start': <member 'start' of 'slice' objects>, 'indices': <method 'indices' of 'slice' objects>, '__ge__': <slot wrapper '__ge__' of 'slice' objects>, 'stop': <member 'stop' of 'slice' objects>, '__eq__': <slot wrapper '__eq__' of 'slice' objects>, 'step': <member 'step' of 'slice' objects>, '__hash__': None, '__doc__': 'slice(stop)\nslice(start, stop[, step])\n\nCreate a slice object. This is used for extended slicing (e.g. a[0:10:2]).', '__repr__': <slot wrapper '__repr__' of 'slice' objects>, '__le__': <slot wrapper '__le__' of 'slice' objects>, '__gt__': <slot wrapper '__gt__' of 'slice' objects>, '__new__': <built-in method __new__ of type object at 0x6A91B420>, '__lt__': <slot wrapper '__lt__' of 'slice' objects>})

#作用于類實(shí)例
>>> class A(object):
  pass

>>> a.__dict__
{}
>>> vars(a)
{}
>>> a.name = 'Kim'
>>> a.__dict__
{'name': 'Kim'}
>>> vars(a)
{'name': 'Kim'}

本函數(shù)是實(shí)現(xiàn)返回對(duì)象object的屬性和屬性值的字典對(duì)象。如果默認(rèn)不輸入?yún)?shù),就打印當(dāng)前調(diào)用位置的屬性和屬性值,相當(dāng)于locals()的功能。如果有參數(shù)輸入,就只打印這個(gè)參數(shù)相應(yīng)的屬性和屬性值。

例子:

#vars() 
 
print(vars()) 
 
class Foo: 
  a = 1 
print(vars(Foo)) 
 
foo = Foo() 
print(vars(foo)) 

結(jié)果輸出如下:

{'Foo': <class '__main__.Foo'>, 'B': <class '__main__.B'>, '__name__': '__main__', '__doc__': None, '__spec__': None,...
{'__module__': '__main__', 'a': 1, '__dict__': <attribute '__dict__' of 'Foo' objects>, '__weakref__': <attribute '__weakref__' of 'Foo' objects>, '__doc__': None}
{}

以上就是本文的全部?jī)?nèi)容,希望對(duì)大家的學(xué)習(xí)有所幫助,也希望大家多多支持腳本之家。

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