如何在一個類中定義一些常量,每個對象都可以方便訪問這些常量而不用重新構造?
class Document():
WELCOME_STR = 'Welcome! The context for this book is {}.'
a=Document()
print type(a)
print dir(a)
print a.WELCOME_STR
C:\Python27\python.exe "C:/Users/TLCB/PycharmProjects/untitled2/python study/t12.py"
<type 'instance'>
['WELCOME_STR', '__doc__', '__module__']
Welcome! The context for this book is {}.
一種很常規的做法,是用全大寫來表示常量,因此我們可以在類中使用 self.WELCOME_STR ,
或者在類外使用 Entity.WELCOME_STR ,來表達這個字符串。
在類外:
node2:/root/python/object#cat t100.py
class Document():
WELCOME_STR = 'Welcome! The context for this book is {}.'
node2:/root/python/object#
node2:/root/python/object#cat t1.py
from t100 import *;
print Document.WELCOME_STR
node2:/root/python/object#
node2:/root/python/object#python t1.py
Welcome! The context for this book is {}.