【Python】【基础知识】【内置函数】【dir的使用方法】
2020-12-13 14:33
标签：admin href ace epo 基础 pes detail mod sdi 原英文帮助文档： Without arguments, return the list of names in the current local scope. With an argument, attempt to return a list of valid attributes for that object. If the object has a method named If the object does not provide The default The resulting list is sorted alphabetically. For example: Note Because ————————（我是分割线）———————— 中文解释： 不带参数，返回当前本地作用域的名称列表。 使用参数，尝试返回该对象的有效属性列表。 如果对象有一个名字叫__dir__() 的方法（函数），则将调用此方法，并且必须返回属性列表。 （大多数常见对象都有__dir__()方法 ） 这允许实现自定义 如果对象不提供__dir__() ，则函数将尽力从对象的__dict__ 属性（如果其已经从类型对象手机信息去定义的话） 结果列表不一定完整，并且在对象具有自定义的__getattr__()时可能不准确。 默认的dir()机制，对不同类型的对象的行为不同，因为它试图生成最相关而不是最完整的信息。 如果对象是模块，则列表包含模块属性的名称。 如果对象是类型或类对象，则列表包含其属性的名称，并递归地包含其基的属性的名称。否则列表将包含对象的属性名、类的属性名，以及类的基类的递归属性名。 结果列表按字母顺序排序，如： 备注： 因为提供dir()主要是为了方便在交互提示下使用，因此它试图提供一组有趣的名称，而不是提供一组严格或一致定义的名称，并且其详细行为可能会在不同版本中发生变化。 例如当参数是类时，元类属性不在结果列表属性中。 ———————（我是分割线）———————— ————————（我是分割线）———————— 参考： 1. Python 3.7.2 documentation 2. RUNOOB.COM：https://www.runoob.com/python/python-func-dir.html 备注： 初次编辑时间：2019年9月21日22:06:44 第一次修改时间：2019年9月21日22:10:14 / 添加环境信息 环境：Windows 7 / Python 3.7.2 【Python】【基础知识】【内置函数】【dir的使用方法】 标签：admin href ace epo 基础 pes detail mod sdi 原文地址：https://www.cnblogs.com/kaixin2018/p/11565094.htmldir([object])__dir__(), this method will be called and must return the list of attributes. This allows objects that implement a custom __getattr__() or __getattribute__() function to customize the way dir() reports their attributes.__dir__(), the function tries its best to gather information from the object’s __dict__ attribute, if defined, and from its type object. The resulting list is not necessarily complete, and may be inaccurate when the object has a custom __getattr__().dir() mechanism behaves differently with different types of objects, as it attempts to produce the most relevant, rather than complete, information:
>>> import struct
>>> dir() # show the names in the module namespace # doctest: +SKIP
[‘__builtins__‘, ‘__name__‘, ‘struct‘]
>>> dir(struct) # show the names in the struct module # doctest: +SKIP
[‘Struct‘, ‘__all__‘, ‘__builtins__‘, ‘__cached__‘, ‘__doc__‘, ‘__file__‘,
‘__initializing__‘, ‘__loader__‘, ‘__name__‘, ‘__package__‘,
‘_clearcache‘, ‘calcsize‘, ‘error‘, ‘pack‘, ‘pack_into‘,
‘unpack‘, ‘unpack_from‘]
>>> class Shape:
... def __dir__(self):
... return [‘area‘, ‘perimeter‘, ‘location‘]
>>> s = Shape()
>>> dir(s)
[‘area‘, ‘location‘, ‘perimeter‘]
dir() is supplied primarily as a convenience for use at an interactive prompt, it tries to supply an interesting set of names more than it tries to supply a rigorously or consistently defined set of names, and its detailed behavior may change across releases. For example, metaclass attributes are not in the result list when the argument is a class.>>> dir()
[‘__annotations__‘, ‘__builtins__‘, ‘__doc__‘, ‘__loader__‘, ‘__name__‘, ‘__package__‘, ‘__spec__‘]
>>>
>>> a = "string"
>>> dir(a)
[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__getnewargs__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__init_subclass__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘capitalize‘, ‘casefold‘, ‘center‘, ‘count‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘, ‘find‘, ‘format‘, ‘format_map‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isascii‘, ‘isdecimal‘, ‘isdigit‘, ‘isidentifier‘, ‘islower‘, ‘isnumeric‘, ‘isprintable‘, ‘isspace‘, ‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘maketrans‘, ‘partition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstrip‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, ‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]
>>>
>>> dir(str)
[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__getnewargs__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__init_subclass__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘capitalize‘, ‘casefold‘, ‘center‘, ‘count‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘, ‘find‘, ‘format‘, ‘format_map‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isascii‘, ‘isdecimal‘, ‘isdigit‘, ‘isidentifier‘, ‘islower‘, ‘isnumeric‘, ‘isprintable‘, ‘isspace‘, ‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘maketrans‘, ‘partition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstrip‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, ‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]
>>>
>>>
__getattr__() 或 __getattribute__()函数的对象自定义dir()报告其属性的方式。>>> import struct
>>> dir() # show the names in the module namespace # doctest: +SKIP
[‘__builtins__‘, ‘__name__‘, ‘struct‘]
>>> dir(struct) # show the names in the struct module # doctest: +SKIP
[‘Struct‘, ‘__all__‘, ‘__builtins__‘, ‘__cached__‘, ‘__doc__‘, ‘__file__‘,
‘__initializing__‘, ‘__loader__‘, ‘__name__‘, ‘__package__‘,
‘_clearcache‘, ‘calcsize‘, ‘error‘, ‘pack‘, ‘pack_into‘,
‘unpack‘, ‘unpack_from‘]
>>> class Shape:
... def __dir__(self):
... return [‘area‘, ‘perimeter‘, ‘location‘]
>>> s = Shape()
>>> dir(s)
[‘area‘, ‘location‘, ‘perimeter‘]
文章标题：【Python】【基础知识】【内置函数】【dir的使用方法】
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