1.創建型模式
單例模式
單例模式（Singleton Pattern）是一種常用的軟件設計模式，該模式的主要目的是確保某一個類只有一個實例存在。當你希望在整個系統中，某個類只能出現一個實例時，單例對象就能派上用場。
比如，某個服務器程序的配置信息存放在一個文件中，客戶端通過一個 AppConfig 的類來讀取配置文件的信息。如果在程序運行期間，有很多地方都需要使用配置文件的內容，也就是說，很多地方都需要創建 AppConfig 對象的實例，這就導致系統中存在多個 AppConfig 的實例對象，而這樣會嚴重浪費內存資源，尤其是在配置文件內容很多的情況下。事實上，類似 AppConfig 這樣的類，我們希望在程序運行期間只存在一個實例對象
1 class Singleton(object): 2 def __init__(self): 3 pass 4 5 def __new__(cls, *args, **kwargs): 6 if not hasattr(Singleton, "_instance"): # 反射 7 Singleton._instance = object.__new__(cls) 8 return Singleton._instance 9 10 obj1 = Singleton() 11 obj2 = Singleton() 12 print(obj1, obj2) #<__main__.Singleton object at 0x004415F0> <__main__.Singleton object at 0x004415F0>
1 class Singleton(object): 2 def __init__(self): 3 pass 4 5 def __new__(cls, *args, **kwargs): 6 if not hasattr(Singleton, "_instance"): # 反射 7 Singleton._instance = object.__new__(cls) 8 return Singleton._instance 9 10 obj1 = Singleton() 11 obj2 = Singleton() 12 print(obj1, obj2) #<__main__.Singleton object at 0x004415F0> <__main__.Singleton object at 0x004415F0>
工廠模式
工廠模式是一個在軟件開發中用來創建對象的設計模式。
工廠模式包涵一個超類。這個超類提供一個抽象化的接口來創建一個特定類型的對象，而不是決定哪個對象可以被創建。
為了實現此方法，需要創建一個工廠類創建並返回。
當程序運行輸入一個“類型”的時候，需要創建於此相應的對象。這就用到了工廠模式。在如此情形中，實現代碼基於工廠模式，可以達到可擴展，可維護的代碼。當增加一個新的類型，不在需要修改已存在的類，只增加能夠產生新類型的子類。
簡短的說，當以下情形可以使用工廠模式：
1.不知道用戶想要創建什么樣的對象
2.當你想要創建一個可擴展的關聯在創建類與支持創建對象的類之間。
一個例子更能很好的理解以上的內容：
- 我們有一個基類Person ，包涵獲取名字，性別的方法 。有兩個子類male 和female，可以打招呼。還有一個工廠類。
- 工廠類有一個方法名getPerson有兩個輸入參數，名字和性別。
- 用戶使用工廠類，通過調用getPerson方法。
在程序運行期間，用戶傳遞性別給工廠，工廠創建一個與性別有關的對象。因此工廠類在運行期，決定了哪個對象應該被創建
class Person:
def __init__(self):
self.name = None
self.gender = None
def getName(self):
return self.name
def getGender(self):
return self.gender
class Male(Person):
def __init__(self, name):
print "Hello Mr." + name
class Female(Person):
def __init__(self, name):
print "Hello Miss." + name
class Factory:
def getPerson(self, name, gender):
if gender == ‘M':
return Male(name)
if gender == 'F':
return Female(name)
if __name__ == '__main__':
factory = Factory()
person = factory.getPerson("Chetan", "M")
class Person:
def __init__(self):
self.name = None
self.gender = None
def getName(self):
return self.name
def getGender(self):
return self.gender
class Male(Person):
def __init__(self, name):
print "Hello Mr." + name
class Female(Person):
def __init__(self, name):
print "Hello Miss." + name
class Factory:
def getPerson(self, name, gender):
if gender == ‘M':
return Male(name)
if gender == 'F':
return Female(name)
if __name__ == '__main__':
factory = Factory()
person = factory.getPerson("Chetan", "M")
建造者模式
將一個復雜對象的構建與它的表示分離，使得同樣的構建過程可以創建不同的表示。
相關模式：思路和模板方法模式很像，模板方法是封裝算法流程，對某些細節，提供接口由子類修改，建造者模式更為高層一點，將所有細節都交由子類實現
一個例子更能很好的理解以上的內容：
1. 有一個接口類，定義創建對象的方法。一個指揮員類，接受創造者對象為參數。兩個創造者類，創建對象方法相同，內部創建可自定義
2.一個指揮員，兩個創造者(瘦子 胖子)，指揮員可以指定由哪個創造者來創造
from abc import ABCMeta, abstractmethod
class Builder():
__metaclass__ = ABCMeta
@abstractmethod
def draw_left_arm(self):
pass
@abstractmethod
def draw_right_arm(self):
pass
@abstractmethod
def draw_left_foot(self):
pass
@abstractmethod
def draw_right_foot(self):
pass
@abstractmethod
def draw_head(self):
pass
@abstractmethod
def draw_body(self):
pass
class Thin(Builder):
def draw_left_arm(self):
print '畫左手'
def draw_right_arm(self):
print '畫右手'
def draw_left_foot(self):
print '畫左腳'
def draw_right_foot(self):
print '畫右腳'
def draw_head(self):
print '畫頭'
def draw_body(self):
print '畫瘦身體'
class Fat(Builder):
def draw_left_arm(self):
print '畫左手'
def draw_right_arm(self):
print '畫右手'
def draw_left_foot(self):
print '畫左腳'
def draw_right_foot(self):
print '畫右腳'
def draw_head(self):
print '畫頭'
def draw_body(self):
print '畫胖身體'
class Director():
def __init__(self, person):
self.person=person
def draw(self):
self.person.draw_left_arm()
self.person.draw_right_arm()
self.person.draw_left_foot()
self.person.draw_right_foot()
self.person.draw_head()
self.person.draw_body()
if __name__=='__main__':
thin=Thin()
fat=Fat()
director_thin=Director(thin)
director_thin.draw()
director_fat=Director(fat)
director_fat.draw()
from abc import ABCMeta, abstractmethod
class Builder():
__metaclass__ = ABCMeta
@abstractmethod
def draw_left_arm(self):
pass
@abstractmethod
def draw_right_arm(self):
pass
@abstractmethod
def draw_left_foot(self):
pass
@abstractmethod
def draw_right_foot(self):
pass
@abstractmethod
def draw_head(self):
pass
@abstractmethod
def draw_body(self):
pass
class Thin(Builder):
def draw_left_arm(self):
print '畫左手'
def draw_right_arm(self):
print '畫右手'
def draw_left_foot(self):
print '畫左腳'
def draw_right_foot(self):
print '畫右腳'
def draw_head(self):
print '畫頭'
def draw_body(self):
print '畫瘦身體'
class Fat(Builder):
def draw_left_arm(self):
print '畫左手'
def draw_right_arm(self):
print '畫右手'
def draw_left_foot(self):
print '畫左腳'
def draw_right_foot(self):
print '畫右腳'
def draw_head(self):
print '畫頭'
def draw_body(self):
print '畫胖身體'
class Director():
def __init__(self, person):
self.person=person
def draw(self):
self.person.draw_left_arm()
self.person.draw_right_arm()
self.person.draw_left_foot()
self.person.draw_right_foot()
self.person.draw_head()
self.person.draw_body()
if __name__=='__main__':
thin=Thin()
fat=Fat()
director_thin=Director(thin)
director_thin.draw()
director_fat=Director(fat)
director_fat.draw()
原型模式
用原型實例指定創建對象的種類，並且通過拷貝這些原型創建新的對象。
原型模式本質就是克隆對象，所以在對象初始化操作比較復雜的情況下，很實用，能大大降低耗時，提高性能，因為“不用重新初始化對象，而是動態地獲得對象運行時的狀態”。
淺拷貝（Shallow Copy）:指對象的字段被拷貝，而字段引用的對象不會被拷貝，拷貝的對象和源對象只是名稱相同，但是他們共用一個實體。
深拷貝（deep copy）:對對象實例中字段引用的對象也進行拷貝。
import copy
from collections import OrderedDict
class Book:
def __init__(self, name, authors, price, **rest):
'''rest的例子有：出版商、長度、標簽、出版日期'''
self.name = name
self.authors = authors
self.price = price # 單位為美元
self.__dict__.update(rest)
def __str__(self):
mylist = []
ordered = OrderedDict(sorted(self.__dict__.items()))
for i in ordered.keys():
mylist.append('{}: {}'.format(i, ordered[i]))
if i == 'price':
mylist.append('$')
mylist.append('\n')
return ''.join(mylist)
class Prototype:
def __init__(self):
self.objects = dict()
def register(self, identifier, obj):
self.objects[identifier] = obj
def unregister(self, identifier):
del self.objects[identifier]
def clone(self, identifier, **attr):
found = self.objects.get(identifier)
if not found:
raise ValueError('Incorrect object identifier: {}'.format(identifier))
obj = copy.deepcopy(found)
obj.__dict__.update(attr)
return obj
def main():
b1 = Book('The C Programming Language', ('Brian W. Kernighan', 'Dennis M.Ritchie'),
price=118, publisher='Prentice Hall', length=228, publication_date='1978-02-22',
tags=('C', 'programming', 'algorithms', 'data structures'))
prototype = Prototype()
cid = 'k&r-first'
prototype.register(cid, b1)
b2 = prototype.clone(cid, name='The C Programming Language(ANSI)', price=48.99,
length=274, publication_date='1988-04-01', edition=2)
for i in (b1, b2):
print(i)
print("ID b1 : {} != ID b2 : {}".format(id(b1), id(b2)))
if __name__ == '__main__':
main()
"""
>>> python3 prototype.py
authors: ('Brian W. Kernighan', 'Dennis M. Ritchie')
length: 228
name: The C Programming Language
price: 118$
publication_date: 1978-02-22
publisher: Prentice Hall
tags: ('C', 'programming', 'algorithms', 'data structures')
authors: ('Brian W. Kernighan', 'Dennis M. Ritchie')
edition: 2
length: 274
name: The C Programming Language (ANSI)
price: 48.99$
publication_date: 1988-04-01
publisher: Prentice Hall
tags: ('C', 'programming', 'algorithms', 'data structures')
ID b1 : 140004970829304 != ID b2 : 140004970829472
"""
import copy
from collections import OrderedDict
class Book:
def __init__(self, name, authors, price, **rest):
'''rest的例子有：出版商、長度、標簽、出版日期'''
self.name = name
self.authors = authors
self.price = price # 單位為美元
self.__dict__.update(rest)
def __str__(self):
mylist = []
ordered = OrderedDict(sorted(self.__dict__.items()))
for i in ordered.keys():
mylist.append('{}: {}'.format(i, ordered[i]))
if i == 'price':
mylist.append('$')
mylist.append('\n')
return ''.join(mylist)
class Prototype:
def __init__(self):
self.objects = dict()
def register(self, identifier, obj):
self.objects[identifier] = obj
def unregister(self, identifier):
del self.objects[identifier]
def clone(self, identifier, **attr):
found = self.objects.get(identifier)
if not found:
raise ValueError('Incorrect object identifier: {}'.format(identifier))
obj = copy.deepcopy(found)
obj.__dict__.update(attr)
return obj
def main():
b1 = Book('The C Programming Language', ('Brian W. Kernighan', 'Dennis M.Ritchie'),
price=118, publisher='Prentice Hall', length=228, publication_date='1978-02-22',
tags=('C', 'programming', 'algorithms', 'data structures'))
prototype = Prototype()
cid = 'k&r-first'
prototype.register(cid, b1)
b2 = prototype.clone(cid, name='The C Programming Language(ANSI)', price=48.99,
length=274, publication_date='1988-04-01', edition=2)
for i in (b1, b2):
print(i)
print("ID b1 : {} != ID b2 : {}".format(id(b1), id(b2)))
if __name__ == '__main__':
main()
"""
>>> python3 prototype.py
authors: ('Brian W. Kernighan', 'Dennis M. Ritchie')
length: 228
name: The C Programming Language
price: 118$
publication_date: 1978-02-22
publisher: Prentice Hall
tags: ('C', 'programming', 'algorithms', 'data structures')
authors: ('Brian W. Kernighan', 'Dennis M. Ritchie')
edition: 2
length: 274
name: The C Programming Language (ANSI)
price: 48.99$
publication_date: 1988-04-01
publisher: Prentice Hall
tags: ('C', 'programming', 'algorithms', 'data structures')
ID b1 : 140004970829304 != ID b2 : 140004970829472
"""
2.結構型模式
適配器模式
所謂適配器模式是指是一種接口適配技術，它可通過某個類來使用另一個接口與之不兼容的類，運用此模式，兩個類的接口都無需改動。
適配器模式主要應用於希望復用一些現存的類，但是接口又與復用環境要求不一致的情況，比如在需要對早期代碼復用一些功能等應用上很有實際價值。
解釋二:
適配器模式(Adapter Pattern):將一個類的接口轉換成為客戶希望的另外一個接口.Adapter Pattern使得原本由於接口不兼容而不能一起工作的那些類可以一起工作.
應用場景:系統數據和行為都正確,但接口不符合時,目的是使控制范圍之外的一個原有對象與某個接口匹配,適配器模式主要應用於希望復用一些現存的類,但接口又與復用環境不一致的情況
class Target(object):
def request(self):
print "普通請求"
class Adaptee(object):
def specific_request(self):
print "特殊請求"
class Adapter(Target):
def __init__(self):
self.adaptee = Adaptee()
def request(self):
self.adaptee.specific_request()
if __name__ == "__main__":
target = Adapter()
target.request()
class Target(object):
def request(self):
print "普通請求"
class Adaptee(object):
def specific_request(self):
print "特殊請求"
class Adapter(Target):
def __init__(self):
self.adaptee = Adaptee()
def request(self):
self.adaptee.specific_request()
if __name__ == "__main__":
target = Adapter()
target.request()
修飾器模式
該模式雖名為修飾器，但這並不意味着它應該只用於讓產品看起來更漂亮。修飾器模式通常用於擴展一個對象的功能。這類擴展的實際例子有，給槍加一個消音器、使用不同的照相機鏡頭
import functools
def memoize(fn):
known = dict()
@functools.wraps(fn)
def memoizer(*args):
if args not in known:
known[args] = fn(*args)
return known[args]
return memoizer
@memoize
def nsum(n):
'''返回前n個數字的和'''
assert(n >= 0), 'n must be >= 0'
return 0 if n == 0 else n + nsum(n-1)
@memoize
def fibonacci(n):
'''返回斐波那契數列的第n個數'''
assert(n >= 0), 'n must be >= 0'
return n if n in (0, 1) else fibonacci(n-1) + fibonacci(n-2)
if __name__ == '__main__':
from timeit import Timer
measure = [ {'exec':'fibonacci(100)', 'import':'fibonacci',
'func':fibonacci},{'exec':'nsum(200)', 'import':'nsum',
'func':nsum} ]
for m in measure:
t = Timer('{}'.format(m['exec']), 'from __main__ import{}'.format(m['import']))
print('name: {}, doc: {}, executing: {}, time:{}'.format(m['func'].__name__, m['func'].__doc__,m['exec'], t.timeit()))
"""
>>> python3 mymath.py
name: fibonacci, doc: Returns the nth number of the Fibonacci
sequence, executing: fibonacci(100), time: 0.4169441329995607
name: nsum, doc: Returns the sum of the first n numbers,
executing: nsum(200), time: 0.4160157349997462
"""
import functools
def memoize(fn):
known = dict()
@functools.wraps(fn)
def memoizer(*args):
if args not in known:
known[args] = fn(*args)
return known[args]
return memoizer
@memoize
def nsum(n):
'''返回前n個數字的和'''
assert(n >= 0), 'n must be >= 0'
return 0 if n == 0 else n + nsum(n-1)
@memoize
def fibonacci(n):
'''返回斐波那契數列的第n個數'''
assert(n >= 0), 'n must be >= 0'
return n if n in (0, 1) else fibonacci(n-1) + fibonacci(n-2)
if __name__ == '__main__':
from timeit import Timer
measure = [ {'exec':'fibonacci(100)', 'import':'fibonacci',
'func':fibonacci},{'exec':'nsum(200)', 'import':'nsum',
'func':nsum} ]
for m in measure:
t = Timer('{}'.format(m['exec']), 'from __main__ import{}'.format(m['import']))
print('name: {}, doc: {}, executing: {}, time:{}'.format(m['func'].__name__, m['func'].__doc__,m['exec'], t.timeit()))
"""
>>> python3 mymath.py
name: fibonacci, doc: Returns the nth number of the Fibonacci
sequence, executing: fibonacci(100), time: 0.4169441329995607
name: nsum, doc: Returns the sum of the first n numbers,
executing: nsum(200), time: 0.4160157349997462
"""
外觀模式
外觀模式又叫做門面模式。在面向對象程序設計中，解耦是一種推崇的理念。但事實上由於某些系統中過於復雜，從而增加了客戶端與子系統之間的耦合度。例如：在家觀看多媒體影院時，更希望按下一個按鈕就能實現影碟機，電視，音響的協同工作，而不是說每個機器都要操作一遍。這種情況下可以采用外觀模式，即引入一個類對子系統進行包裝，讓客戶端與其進行交互。
外觀模式(Facade Pattern)：外部與一個子系統的通信必須通過一個統一的外觀對象進行，為子系統中的一組接口提供一個一致的界面，外觀模式定義了一個高層接口，這個接口使得這一子系統更加容易使用。外觀模式又稱為門面模式，它是一種對象結構型模式。
from enum import Enum
from abc import ABCMeta, abstractmethod
State = Enum('State', 'new running sleeping restart zombie')
class User:
pass
class Process:
pass
class File:
pass
class Server(metaclass=ABCMeta):
@abstractmethod
def __init__(self):
pass
def __str__(self):
return self.name
@abstractmethod
def boot(self):
pass
@abstractmethod
def kill(self, restart=True):
pass
class FileServer(Server):
def __init__(self):
'''初始化文件服務進程要求的操作'''
self.name = 'FileServer'
self.state = State.new
def boot(self):
print('booting the {}'.format(self))
'''啟動文件服務進程要求的操作'''
self.state = State.running
def kill(self, restart=True):
print('Killing {}'.format(self))
'''終止文件服務進程要求的操作'''
self.state = State.restart if restart else State.zombie
def create_file(self, user, name, permissions):
'''檢查訪問權限的有效性、用戶權限等'''
print("trying to create the file '{}' for user '{}' with permissions{}".format(name, user, permissions))
class ProcessServer(Server):
def __init__(self):
'''初始化進程服務進程要求的操作'''
self.name = 'ProcessServer'
self.state = State.new
def boot(self):
print('booting the {}'.format(self))
'''啟動進程服務進程要求的操作'''
self.state = State.running
def kill(self, restart=True):
print('Killing {}'.format(self))
'''終止進程服務進程要求的操作'''
self.state = State.restart if restart else State.zombie
def create_process(self, user, name):
'''檢查用戶權限和生成PID等'''
print("trying to create the process '{}' for user '{}'".format(name, user))
class WindowServer:
pass
class NetworkServer:
pass
class OperatingSystem:
'''外觀'''
def __init__(self):
self.fs = FileServer()
self.ps = ProcessServer()
def start(self):
[i.boot() for i in (self.fs, self.ps)]
def create_file(self, user, name, permissions):
return self.fs.create_file(user, name, permissions)
def create_process(self, user, name):
return self.ps.create_process(user, name)
def main():
os = OperatingSystem()
os.start()
os.create_file('foo', 'hello', '-rw-r-r')
os.create_process('bar', 'ls /tmp')
if __name__ == '__main__':
main()
"""
booting the FileServer
booting the ProcessServer
trying to create the file 'hello' for user 'foo' with permissions-rw-r-r
trying to create the process 'ls /tmp' for user 'bar'
"""
from enum import Enum
from abc import ABCMeta, abstractmethod
State = Enum('State', 'new running sleeping restart zombie')
class User:
pass
class Process:
pass
class File:
pass
class Server(metaclass=ABCMeta):
@abstractmethod
def __init__(self):
pass
def __str__(self):
return self.name
@abstractmethod
def boot(self):
pass
@abstractmethod
def kill(self, restart=True):
pass
class FileServer(Server):
def __init__(self):
'''初始化文件服務進程要求的操作'''
self.name = 'FileServer'
self.state = State.new
def boot(self):
print('booting the {}'.format(self))
'''啟動文件服務進程要求的操作'''
self.state = State.running
def kill(self, restart=True):
print('Killing {}'.format(self))
'''終止文件服務進程要求的操作'''
self.state = State.restart if restart else State.zombie
def create_file(self, user, name, permissions):
'''檢查訪問權限的有效性、用戶權限等'''
print("trying to create the file '{}' for user '{}' with permissions{}".format(name, user, permissions))
class ProcessServer(Server):
def __init__(self):
'''初始化進程服務進程要求的操作'''
self.name = 'ProcessServer'
self.state = State.new
def boot(self):
print('booting the {}'.format(self))
'''啟動進程服務進程要求的操作'''
self.state = State.running
def kill(self, restart=True):
print('Killing {}'.format(self))
'''終止進程服務進程要求的操作'''
self.state = State.restart if restart else State.zombie
def create_process(self, user, name):
'''檢查用戶權限和生成PID等'''
print("trying to create the process '{}' for user '{}'".format(name, user))
class WindowServer:
pass
class NetworkServer:
pass
class OperatingSystem:
'''外觀'''
def __init__(self):
self.fs = FileServer()
self.ps = ProcessServer()
def start(self):
[i.boot() for i in (self.fs, self.ps)]
def create_file(self, user, name, permissions):
return self.fs.create_file(user, name, permissions)
def create_process(self, user, name):
return self.ps.create_process(user, name)
def main():
os = OperatingSystem()
os.start()
os.create_file('foo', 'hello', '-rw-r-r')
os.create_process('bar', 'ls /tmp')
if __name__ == '__main__':
main()
"""
booting the FileServer
booting the ProcessServer
trying to create the file 'hello' for user 'foo' with permissions-rw-r-r
trying to create the process 'ls /tmp' for user 'bar'
"""
享元模式
運用共享技術有效地支持大量細粒度的對象。
內部狀態：享元對象中不會隨環境改變而改變的共享部分。比如圍棋棋子的顏色。
外部狀態：隨環境改變而改變、不可以共享的狀態就是外部狀態。比如圍棋棋子的位置。
應用場景：程序中使用了大量的對象，如果刪除對象的外部狀態，可以用相對較少的共享對象取代很多組對象，就可以考慮使用享元模式。
1 import random
2 from enum import Enum
3 TreeType = Enum('TreeType', 'apple_tree cherry_tree peach_tree')
4
5 class Tree:
6 pool = dict()
7 def __new__(cls, tree_type):
8 obj = cls.pool.get(tree_type, None)
9 if not obj:
10 obj = object.__new__(cls)
11 cls.pool[tree_type] = obj
12 obj.tree_type = tree_type
13 return obj
14
15 def render(self, age, x, y):
16 print('render a tree of type {} and age {} at ({}, {})'.format(self.tree_type, age, x, y))
17
18
19 def main():
20 rnd = random.Random()
21 age_min, age_max = 1, 30 # 單位為年
22 min_point, max_point = 0, 100
23 tree_counter = 0
24 for _ in range(10):
25 t1 = Tree(TreeType.apple_tree)
26 t1.render(rnd.randint(age_min, age_max),
27 rnd.randint(min_point, max_point),
28 rnd.randint(min_point, max_point))
29 tree_counter += 1
30 for _ in range(3):
31 t2 = Tree(TreeType.cherry_tree)
32 t2.render(rnd.randint(age_min, age_max),
33 rnd.randint(min_point, max_point),
34 rnd.randint(min_point, max_point))
35 tree_counter += 1
36 for _ in range(5):
37 t3 = Tree(TreeType.peach_tree)
38 t3.render(rnd.randint(age_min, age_max),
39 rnd.randint(min_point, max_point),
40 rnd.randint(min_point, max_point))
41 tree_counter += 1
42
43 print('trees rendered: {}'.format(tree_counter))
44 print('trees actually created: {}'.format(len(Tree.pool)))
45 t4 = Tree(TreeType.cherry_tree)
46 t5 = Tree(TreeType.cherry_tree)
47 t6 = Tree(TreeType.apple_tree)
48 print('{} == {}? {}'.format(id(t4), id(t5), id(t4) == id(t5)))
49 print('{} == {}? {}'.format(id(t5), id(t6), id(t5) == id(t6)))
50
51 main()
52
53 """
54 render a tree of type TreeType.apple_tree and age 28 at (29, 80)
55 render a tree of type TreeType.apple_tree and age 28 at (38, 94)
56 render a tree of type TreeType.apple_tree and age 16 at (82, 84)
57 render a tree of type TreeType.apple_tree and age 18 at (43, 98)
58 render a tree of type TreeType.apple_tree and age 2 at (84, 72)
59 render a tree of type TreeType.apple_tree and age 16 at (89, 29)
60 render a tree of type TreeType.apple_tree and age 30 at (91, 53)
61 render a tree of type TreeType.apple_tree and age 12 at (92, 73)
62 render a tree of type TreeType.apple_tree and age 3 at (11, 54)
63 render a tree of type TreeType.apple_tree and age 1 at (34, 59)
64 render a tree of type TreeType.cherry_tree and age 11 at (67, 72)
65 render a tree of type TreeType.cherry_tree and age 27 at (65, 81)
66 render a tree of type TreeType.cherry_tree and age 27 at (10, 48)
67 render a tree of type TreeType.peach_tree and age 11 at (35, 38)
68 render a tree of type TreeType.peach_tree and age 3 at (58, 83)
69 render a tree of type TreeType.peach_tree and age 18 at (73, 50)
70 render a tree of type TreeType.peach_tree and age 24 at (94, 3)
71 render a tree of type TreeType.peach_tree and age 4 at (2, 9)
72 trees rendered: 18
73 trees actually created: 3
74 4866032 == 4866032? True
75 4866032 == 4742704? False
76
77 """
享元模式
1 import random
2 from enum import Enum
3 TreeType = Enum('TreeType', 'apple_tree cherry_tree peach_tree')
4
5 class Tree:
6 pool = dict()
7 def __new__(cls, tree_type):
8 obj = cls.pool.get(tree_type, None)
9 if not obj:
10 obj = object.__new__(cls)
11 cls.pool[tree_type] = obj
12 obj.tree_type = tree_type
13 return obj
14
15 def render(self, age, x, y):
16 print('render a tree of type {} and age {} at ({}, {})'.format(self.tree_type, age, x, y))
17
18
19 def main():
20 rnd = random.Random()
21 age_min, age_max = 1, 30 # 單位為年
22 min_point, max_point = 0, 100
23 tree_counter = 0
24 for _ in range(10):
25 t1 = Tree(TreeType.apple_tree)
26 t1.render(rnd.randint(age_min, age_max),
27 rnd.randint(min_point, max_point),
28 rnd.randint(min_point, max_point))
29 tree_counter += 1
30 for _ in range(3):
31 t2 = Tree(TreeType.cherry_tree)
32 t2.render(rnd.randint(age_min, age_max),
33 rnd.randint(min_point, max_point),
34 rnd.randint(min_point, max_point))
35 tree_counter += 1
36 for _ in range(5):
37 t3 = Tree(TreeType.peach_tree)
38 t3.render(rnd.randint(age_min, age_max),
39 rnd.randint(min_point, max_point),
40 rnd.randint(min_point, max_point))
41 tree_counter += 1
42
43 print('trees rendered: {}'.format(tree_counter))
44 print('trees actually created: {}'.format(len(Tree.pool)))
45 t4 = Tree(TreeType.cherry_tree)
46 t5 = Tree(TreeType.cherry_tree)
47 t6 = Tree(TreeType.apple_tree)
48 print('{} == {}? {}'.format(id(t4), id(t5), id(t4) == id(t5)))
49 print('{} == {}? {}'.format(id(t5), id(t6), id(t5) == id(t6)))
50
51 main()
52
53 """
54 render a tree of type TreeType.apple_tree and age 28 at (29, 80)
55 render a tree of type TreeType.apple_tree and age 28 at (38, 94)
56 render a tree of type TreeType.apple_tree and age 16 at (82, 84)
57 render a tree of type TreeType.apple_tree and age 18 at (43, 98)
58 render a tree of type TreeType.apple_tree and age 2 at (84, 72)
59 render a tree of type TreeType.apple_tree and age 16 at (89, 29)
60 render a tree of type TreeType.apple_tree and age 30 at (91, 53)
61 render a tree of type TreeType.apple_tree and age 12 at (92, 73)
62 render a tree of type TreeType.apple_tree and age 3 at (11, 54)
63 render a tree of type TreeType.apple_tree and age 1 at (34, 59)
64 render a tree of type TreeType.cherry_tree and age 11 at (67, 72)
65 render a tree of type TreeType.cherry_tree and age 27 at (65, 81)
66 render a tree of type TreeType.cherry_tree and age 27 at (10, 48)
67 render a tree of type TreeType.peach_tree and age 11 at (35, 38)
68 render a tree of type TreeType.peach_tree and age 3 at (58, 83)
69 render a tree of type TreeType.peach_tree and age 18 at (73, 50)
70 render a tree of type TreeType.peach_tree and age 24 at (94, 3)
71 render a tree of type TreeType.peach_tree and age 4 at (2, 9)
72 trees rendered: 18
73 trees actually created: 3
74 4866032 == 4866032? True
75 4866032 == 4742704? False
76
77 """
模型-視圖-控制器模式
代理模式
3.行為型模式
責任鏈模式
命令模式
解釋器模式
觀察者模式
狀態模式
策略模式
模板模式