1 单例模式
核心思想
主要是应用于全局变量，例如日志生成器logger，全局应只定义一个。
实现方法是重写类内置函数new(cls)，不进行新的创建，同时利用内部私有类存储方法和属性。
Example
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| class SingletonObject(object):
class __SingletonObject():
def __init__(self):
self.val = None
def __str__(self):
return "{0!r} {1}".format(self, self.val)
instance = None
def __new__(cls):
if not SingletonObject.instance:
SingletonObject.instance = SingletonObject.__SingletonObject()
return SingletonObject.instance
def __getattr__(self, name):
return getattr(self.instance, name)
def __setattr__(self, name):
return setattr(self.instance, name)
|
2 原型模式
核心思想
建立实例时，防止频繁读取配置文件
Example
prototype_1.py
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| from abs import ABCMeta, abstractmethod
class Prototype(metaclass=ABCMeta):
@abstractmethod
def clone(self):
pass
|
concrete.py
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| from prototype_1 import Prototype
from copy import deepcopy
class Concrete(Prototype):
def clone(self):
return deepcopy(self)
|
rts_prototype.py
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| from prototype_1 import Prototype
from copy import deepcopy
class Knight(Prototype):
def __init__(self, level):
self.unit_type = "Knight"
filename = "{}_{}.bat".format(self.unit_type, level)
with open(filename, 'r') as parameter_file:
pass
def __str__(self):
pass
def clone(self):
return deepcopy(self)
class Archer(Prototype):
def __init__(self, level):
self.unit_type = "Archer"
filename = "{}_{}.bat".format(self.unit_type, level)
with open(filename, 'r') as parameter_file:
pass
def __str__(self):
pass
def clone(self):
return deepcopy(self)
class Barracks(object):
def __init__(self):
self.units = {
"knight": {
1: Knight(1),
2: Knight(2)
},
"archer": {
1: Archer(1),
2: Archer(2)
}
}
def build_unit(self, unit_type, level):
return self.units[unit_type][level].clone()
|
3 工厂模式
Reference
- 《Python设计模式》, [美]Wessel Badenhorst；蒲成译，清华大学出版社，2019
