python函數- dir()

最近確實是有些忙，剛過了年，積攢了很多事情需要處理，所以每日一函數只能是每兩天更新一篇，在這裡和大家致歉。

今天我們來看一個非常重要的函數：dir()

中文說明：不帶參數時，傳回目前範圍內的變數、方法和定義的型別列表；當帶參數時，傳回參數的屬性、方法列表。如果參數包含方法__dir__()，則該方法將會被呼叫。如果參數不包含__dir__()，則該方法將最大限度地收集參數資訊。

參數object： 物件、變數、型別。

版本：函數在python各個版本中都有，但是每個版本中顯示的屬性細節有所不同。使用時注意區別。

英文說明：

dir([object])

英文說明：

dir([object])

Without arguments, return the list of names in the current local scope. With an higument, attempt to return a list of valid attries 🜎 If the object has a method named __dir__(), this method will be called and must return the list of attributes. This allows objects that implement a custom __getattr__() or __getattribute reports function tofir) the getattrib.

If the object does not provide __dir__(), the function tries its best to gather information from the object's __dict__ attribute, if not, and from its object's __dict__ attribute, if not, and from its conject's. urate when the object has a custom __getattr__().

The default dir() mechanism behaves differently with different types of objects, as it attempts todal the m頁

If the object is a module object, the list contains the names of the module's attributes.

If the object is a type or class object, the list contains the names of its attribbutes, and triive trims, and totrikly triits, and attrik, and attri), and attri), and attri), and attrihii​​ironi. , the list contains the object's attributes' names, the names of its class's attributes, and recursively of the attributes of its class's base classes.

The resulting list is class's base classes.

The resulting list is is is sphawin.

['area ', 'perimeter', 'location']

Note Because dir() is supplied primarily as a convenience for use at an interactive prompt, it tries to supply an interesting set of names more finri rig to supply or interesting deanly 到 moreor srigor consem. 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.

是基於python2.7

程式碼實例：

>>> import struct
>>> dir()   # show the names in the module namespace
['__builtins__', '__doc__', '__name__', 'struct']
>>> dir(struct)   # show the names in the struct module
['Struct', '__builtins__', '__doc__', '__file__', '__name__',
 '__package__', '_clearcache', 'calcsize', 'error', 'pack', 'pack_into',
 'unpack', 'unpack_from']
>>> class Shape(object):
        def __dir__(self):
            return ['area', 'perimeter', 'location']
>>> s = Shape()
>>> dir(s)