本文主要是介绍python实现享元模式,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
"""
享元模式
将不可变(可共享)的属性与可变的属性分开
"""
import random
from enum import Enum
TreeType = Enum('TreeType', 'apple_tree cherry_tree peach_tree')
class Tree:
pool = dict()
def __new__(cls, tree_type):
obj = cls.pool.get(tree_type)
if not obj:
obj = object.__new__(cls)
cls.pool[tree_type] = obj
obj.tree_type = tree_type
return obj
def render(self, age, x, y):
print('render a tree of type {} and age {} at ({}, {})'.format(self.tree_type, age, x, y))
def main():
rnd = random.Random()
age_min, age_max = 1, 30
min_point, max_point = 0, 100
tree_counter = 0
for _ in range(10):
t1 = Tree(TreeType.apple_tree)
t1.render(rnd.randint(age_min, age_max),
rnd.randint(min_point, max_point),
rnd.randint(min_point, max_point)
)
tree_counter += 1
for _ in range(3):
t2 = Tree(TreeType.cherry_tree)
t2.render(rnd.randint(age_min, age_max),
rnd.randint(min_point, max_point),
rnd.randint(min_point, max_point)
)
tree_counter += 1
for _ in range(5):
t3 = Tree(TreeType.peach_tree)
t3.render(rnd.randint(age_min, age_max),
rnd.randint(min_point, max_point),
rnd.randint(min_point, max_point)
)
tree_counter += 1
print('trees rendered: {}'.format(tree_counter))
print('trees actually created: {}'.format(len(Tree.pool)))
t4 = Tree(TreeType.cherry_tree)
t5 = Tree(TreeType.cherry_tree)
t6 = Tree(TreeType.apple_tree)
print('{} == {}? {}'.format(id(t4), id(t5), id(t4) == id(t5)))
print('{} == {}? {}'.format(id(t5), id(t6), id(t5) == id(t6)))
if __name__ == '__main__':
main()
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