93 lines
1.9 KiB
Python
93 lines
1.9 KiB
Python
|
#!/usr/bin/env python
|
||
|
|
# -*- encoding: utf-8 -*-
|
||
|
|
"""
|
||
|
|
Topic: 扩展property的功能
|
||
|
|
Desc :
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
class Person:
|
||
|
|
def __init__(self, name):
|
||
|
|
self.name = name
|
||
|
|
|
||
|
|
# Getter function
|
||
|
|
@property
|
||
|
|
def name(self):
|
||
|
|
return self._name
|
||
|
|
|
||
|
|
# Setter function
|
||
|
|
@name.setter
|
||
|
|
def name(self, value):
|
||
|
|
if not isinstance(value, str):
|
||
|
|
raise TypeError('Expected a string')
|
||
|
|
self._name = value
|
||
|
|
|
||
|
|
# Deleter function
|
||
|
|
@name.deleter
|
||
|
|
def name(self):
|
||
|
|
raise AttributeError("Can't delete attribute")
|
||
|
|
|
||
|
|
|
||
|
|
class SubPerson(Person):
|
||
|
|
@property
|
||
|
|
def name(self):
|
||
|
|
print('Getting name')
|
||
|
|
return super().name
|
||
|
|
|
||
|
|
@name.setter
|
||
|
|
def name(self, value):
|
||
|
|
print('Setting name to', value)
|
||
|
|
super(SubPerson, SubPerson).name.__set__(self, value)
|
||
|
|
|
||
|
|
@name.deleter
|
||
|
|
def name(self):
|
||
|
|
print('Deleting name')
|
||
|
|
super(SubPerson, SubPerson).name.__delete__(self)
|
||
|
|
|
||
|
|
|
||
|
|
s = SubPerson('Guido')
|
||
|
|
print(s.name)
|
||
|
|
s.name = 'Larry'
|
||
|
|
|
||
|
|
|
||
|
|
# A descriptor
|
||
|
|
class String:
|
||
|
|
def __init__(self, name):
|
||
|
|
self.name = name
|
||
|
|
|
||
|
|
def __get__(self, instance, cls):
|
||
|
|
if instance is None:
|
||
|
|
return self
|
||
|
|
return instance.__dict__[self.name]
|
||
|
|
|
||
|
|
def __set__(self, instance, value):
|
||
|
|
if not isinstance(value, str):
|
||
|
|
raise TypeError('Expected a string')
|
||
|
|
instance.__dict__[self.name] = value
|
||
|
|
|
||
|
|
|
||
|
|
# A class with a descriptor
|
||
|
|
class Person:
|
||
|
|
name = String('name')
|
||
|
|
|
||
|
|
def __init__(self, name):
|
||
|
|
self.name = name
|
||
|
|
|
||
|
|
|
||
|
|
# Extending a descriptor with a property
|
||
|
|
class SubPerson(Person):
|
||
|
|
@property
|
||
|
|
def name(self):
|
||
|
|
print('Getting name')
|
||
|
|
return super().name
|
||
|
|
|
||
|
|
@name.setter
|
||
|
|
def name(self, value):
|
||
|
|
print('Setting name to', value)
|
||
|
|
super(SubPerson, SubPerson).name.__set__(self, value)
|
||
|
|
|
||
|
|
@name.deleter
|
||
|
|
def name(self):
|
||
|
|
print('Deleting name')
|
||
|
|
super(SubPerson, SubPerson).name.__delete__(self)
|