Python中dir()与help()的使用

Posted 2020-12-28 fireporsche

python内置了很多内置函数、类方法属性及各种模块。当我们想要当我们想要了解某种类型有哪些属性方法以及每种方法该怎么使用时，我们可以使用dir()函数和help()函数在python idle交互式模式下获得我们想要的信息。

dir()

dir()用来查询一个类或者对象所有属性，比如：

>>> dir(list)
[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__gt__‘, ‘__hash__‘, ‘__iadd__‘, ‘__imul__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__reversed__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__setitem__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘append‘, ‘clear‘, ‘copy‘, ‘count‘, ‘extend‘, ‘index‘, ‘insert‘, ‘pop‘, ‘remove‘, ‘reverse‘, ‘sort‘]
>>>

help()

help()函数帮助我们了解模块、类型、对象、方法、属性的详细信息

1.帮助查看类型详细信息，包含类的创建方式、属性、方法

>>> help(list)
Help on class list in module builtins:

class list(object)
 |  list() -> new empty list
 |  list(iterable) -> new list initialized from iterable‘s items
 |
 |  Methods defined here:
 |
 |  __add__(self, value, /)
 |      Return self+value.
 |
 |  __contains__(self, key, /)
 |      Return key in self.
 |
 |  __delitem__(self, key, /)
 |      Delete self[key].
 |
 |  __eq__(self, value, /)
 |      Return self==value.
 |
 |  __ge__(self, value, /)
 |      Return self>=value.
 |
 |  __getattribute__(self, name, /)
 |      Return getattr(self, name).
 |
 |  __getitem__(...)
 |      x.__getitem__(y) <==> x[y]
 |
 |  __gt__(self, value, /)
 |      Return self>value.
 |
 |  __iadd__(self, value, /)
 |      Implement self+=value.
 |
 |  __imul__(self, value, /)
 |      Implement self*=value.
 |
 |  __init__(self, /, *args, **kwargs)
-- More  --

2.帮助查看方法的详细使用信息（使用时要注意输入完整路径，使用模块帮助时，需要先导入模块）

>>> from selenium.webdriver.common.by import By
>>> help(By)
Help on class By in module selenium.webdriver.common.by:

class By(builtins.object)
 |  Set of supported locator strategies.
 |
 |  Data descriptors defined here:
 |
 |  __dict__
 |      dictionary for instance variables (if defined)
 |
 |  __weakref__
 |      list of weak references to the object (if defined)
 |
 |  ----------------------------------------------------------------------
 |  Data and other attributes defined here:
 |
 |  CLASS_NAME = ‘class name‘
 |
 |  CSS_SELECTOR = ‘css selector‘
 |
 |  ID = ‘id‘
 |
 |  LINK_TEXT = ‘link text‘
 |
 |  NAME = ‘name‘
 |
 |  PARTIAL_LINK_TEXT = ‘partial link text‘
 |
 |  TAG_NAME = ‘tag name‘
 |
 |  XPATH = ‘xpath‘

>>>