為元組中的每個元素命名，提高程式可讀性
元組中，使用索引(index)訪問時，會出現大量索引，降低程式的可讀性。
解決方法：
1： 定義類似與其他語言的列舉型別，也就是定義一系列數值常量
eg_v1:定義一個學生資訊的元組，包括姓名，年齡，性別，郵箱
("aaaa",22,"boy","aaaaa@123.com")
("bbbb",20,"boy","bbbbb@123.com")
("cccc",22,"girl","ccccc@123.com")
("dddd",21,"girl","ddddd@123.com")
Name = 0
Age = 1
Sex = 2
Email = 3
或者： Name,Age,Sex,Email = xrange(4)
student = ("aaaa",22,"boy","aaaaa@123.com")
# name
print (student[Name])
# aaaa
# age
print (student[Age])
# 22
# sex
print (student[Sex])
# boy
# email
print (student[Email])
# aaaaa@123.com
2： 使用標準庫中的collection.namedtuple函式替換內建tuple函式
from collections import namedtuple # 匯入namedtuple包
Student = namedtuple("Student",["name","age","sex","email"])
s = Student("aaaa",22,"boy","aaaaa@123.com") # 位置傳參
print (s)
# Student(name='eeee', age=25, sex='boy', email='eeeee@123.com')
s2 = Student(name="eeee",age=25,sex="boy",email="eeeee@123.com") # # 關鍵字傳參
print (s2)
# Student(name='eeee', age=25, sex='boy', email='eeeee@123.com')
print (s.name)
# aaaa
print (s.age)
# 22
print (s.sex)
# boy
print (s.email)
# aaaaa@123.com
print (isinstance(s,tuple)) # 判斷是否為tuple元組的子類
# True
namedtuple 函式的幫助手冊：
>>> help(namedtuple)
Help on function namedtuple in module collections:
namedtuple(typename, field_names, verbose=False, rename=False)
Returns a new subclass of tuple with named fields.
>>> Point = namedtuple('Point', ['x', 'y'])
>>> Point.__doc__ # docstring for the new class
'Point(x, y)'
>>> p = Point(11, y=22) # instantiate with positional args or keywords
>>> p[0] + p[1] # indexable like a plain tuple
33
>>> x, y = p # unpack like a regular tuple
>>> x, y
(11, 22)
>>> p.x + p.y # fields also accessible by name
33
>>> d = p._asdict() # convert to a dictionary
>>> d['x']
11
>>> Point(**d) # convert from a dictionary
Point(x=11, y=22)
>>> p._replace(x=100) # _replace() is like str.replace() but targets named fields
Point(x=100, y=22)
>>>